A tory upper L 33- ELTRLLT‘ DUCDEgéL FISTULA TECHSIRUES: Ai'i’nloAll-cm T3 ‘igiE‘; [3";le OE DILEST‘ZC‘I ACE PASSAGE It; T13; €011-53 ALIlEZCA‘Y TRACT By A. Dere LcGiiliero preliminery study H88 conducted to devel;o e se¢isfec— grocedure for measuring totel output of in; ste from the put. ihe procedure adooted was used to psrtition diges— tion in the upper fron tnet in tse lover gut. (‘0 Up Iistul etive technicue I r estcoiis i1: 2 re—ertrsht duodensl e in the bovine wes developed. Equipment res Zesigned for the totel collection of ingests fron the utper gut end its return to the lower gut. Pessege mes nersured using three netnods: I - none of th e co lect; -d ing ests res returned to tne lower gut; II - all of the ingest? octeined (urirg eech 15-minute period was returned to the lower gut Pt tie end of 3J8 period; III - ingests we commenced with feedini, were of 6 hours durztion PLd consiste U) " 4 ‘ Q -~ Q? ~ 4- fl “ 7 ‘ continuousl¢ r turnet to tne loner ‘— about the sen e r: te es it mes collected. All collections {)4 of consecutive 15—minute and hourly Beagling periods. Ten pounds daily '— *1 1 tive 1:: bility. Ingeste passed from the u; per of a 70» elfelfe hey—50$ ground corn diet wes fed once throughout the study. istulstion appezred to hgve no merged influence on diges— ut st irre :ul (D I’ ("-3 m but reletively frequent intervals. The return of lerge amounts of infiesta to the lower gut reduced or stOpped flow for a . .. $3 a ‘1» ybrluu or time. Passage ves most regid durin: eating but A. Dare ncGilliard decreased with time thereafter. The total output, solids Content and pH of intesta a neared to ca related to the extent of dilution in the aoonasun. Abnormal behaviour during col- lections was observed when nethods I and II were used. Flow of intesta with method II use highly vrriable. Passage of the OPéELiC comgonents and their decline after feeding vas narhedly accelerated with method I. Ihe least variation within and be- tween collections occurred vith nethod III; behaviour of the animal was normal. The steer used in the preliminary studv KFS also used for the second part of the studv. Four diets consisting of various alfalfa hayzground corn ratios (10:3, 7:3, 3:7, 0:10) vere fed at constant intane (10 lb./day) either once or twice daily. iotal digestion was determined by the ratio technicue using chronic oxide as a marker. Dioestion in and passage fron the C. A) _.l s determined by to; m upper gut t L collection of inaesta nFSSlng from the proximal duodenum over a ne-hour period; the 'con— tinuous' method of ceilection was used. Digestion in the 10*er gut was determined by difference. From né—odp of the dry matter was removed in the upper gut and a5-4et was renoved in the lo er gut. Proportionately less dry matter was digested in the upper gut and pronortion- ately more was digested in the lower gut with nixed diets than with corn or hay alone. Ron-dietary nitrOgen, ether extract and ash were added to ingesta in the upper gut; removal of these fractions largely occurred in the lover gut. Losses in A. Dare LcGilliard the upper Lut were alnost entirely due to renoval of the car— bohydrate fractions. Flow of inéesta from the upper gut was essentially con- tinuous uith each diet. In esta pH was not influenced appre— ciably by diet or frequency of feeding. An estfnated net increase of 08-54 1. of water occurred in the ufper gut. Pas— saie has nost rapid with the high—corn diet and was followed in order of decreasing rate by the hith-hay, sLJ—ha~ and ail— corn diets. Passage was accelerated during satin: and reduced by rumination and more frequent feeding. Cutput of ingesta decreased with tine after feeding. Eecrease of the carbo— hydrate fractions was relatively more rayid thrh that of protein or ether extract. PhysioloEically, the animal vas undisturbed by the ze—hour collection procedure. H "a F‘. A m “.vv.f\ HV'1I.T ”T 27:17"? r :70 fl Rita-14 UL. .LLLLI‘LI “L UJUDLL.L‘3L_J I‘lQLuLulL -4 .. ":I‘cbjhas AriLICAIIOl IQ “i5 SIUDI OF DIG: STICK AID PA SAG" II. THE EOVIIE ALILEIITE‘ELI TRACT A. Dare thilliard (I) A T-IE IS Submitted to nichigan State University partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Dairy 1961 r/ \l/ / 4". ' ’ ), /-:. .9 4v L’ ./~ 72. 419/ I“ I 11 ACKNOWLEDGEMENTS The author wishes to express his sincere appreciation to Dr. C. F. Huffman for his eternal patience, helpful criticisms and valuable suggestions during the course of the study and preparation of this manuscript. He is also grateful to Dr. Earl teaver for his advice and encouragement, to Dr. G. H. Conner for his skillful development and performance of the surgery, to hr. R. N. Berry for his aid in design and con- struction of the collection and re-introduction equipment and to Mr. C. W. Duncan and Dr. E. J. Benne for their cooperation in carrying out the analytical work. The experience and asso- ciations with this research group have been invaluable. Finally, I am unable to eXpress adequately my grateful- ness to my wife, Margaret, and to my parents, hr. and hrs. P. C. thilliard, for their enduring patience and for their unending encouragement during this tenure of graduate study. _, "~quO-v ,.-..~ .— ,. I o .- ‘O - . n. s . .n41 -- — - nu, ‘ -.. .., . c ._v e A .. ~ " .. " _. , 5 ~ ., . ,. . .“ , < 0...: ‘ \ D"- .‘: 'I._ ’ ' ‘ .“0-.s - “ 5- u. . -r~ A“ . .r ‘. o I; :ROD TLOIJ o . . TmVIEJ OF LITERATURE Anatomical Considerations of the Alimentary Tract The Course Follored by Food Throlgh the Alimentary Tract. . . . . . . . The Rate of Passage of Food Through the Alimentary Tract. . . . . . . l .ethods of investigation Expressior. s of rate of pa ssa . . Rate of passace — factors inIluencing rate of passag e. . . . . Regwul tion of Passage Throug; the Alimentary Tract . . . . . Ch nanues in the Incesta Passirg Tqrutbl the Allmenbcry lTSCt . . I.ethods of investigation Jater and dr; matter The carbohydrate constituents. The nitrogenous cons stituents The lipid constituents The inorganic constituents Summary . PRELIRILARI EXPERILEKT Experimental Procedure. Establishment of re-entrant duodenal fistula U-tube. . . . . . . . . . . . . . Cannulae. . . . . . . . . . . . . . . . Surgery Rations and feeding procedure. . . . Pre— and post-surgical digestion trials. Duodenal trials. . . . . . . . . . . . . . Metabolism stall. . T1 .21) W) .s H W U: Q a can F4 CD CD 0‘ O) O) 03 c: 0 iv! 93 127 146 151 158 171 171 171 171 171 172 181 181 182 "‘va 'ho\_- wu . g... _ .. u..-‘ .-, ~~v . - ‘ n. u s - . . Kg”. . . 1. 1"... ‘1. .. _ Q ‘vo.' ‘ ~" ua§t ..' u t. a- V 1“ g s.' ...~. o;‘ .‘ . \ ‘- um". ‘_ a . .v n _ ~ " AL . . Q '~ '7. . t .. . o _ ,s ~ — ‘Q '. 4,. ~ - . O‘ . ‘\ ._ ~ h‘ ~ \ v iv Collection and re-introduction apparatus . . . . . . . . . Collection and san lin. procedure . . . Chemical analyses. . . . . . Results . . . . . . . . The experimental animal. . . . . Effect of fistulation on digestion . . . Establishment of method of collection . . . Physiological effects of nethod of collection. . . . . . . . . . . . . . Effect of nethod of collection on eating and rumination . . . . Effect of met;od of collection on pattern of flow of inaesta. . Effect of method of collection on pLI of in. as ta . . . . . . . . . Effect of neV 05 of collection on the passage of ingesta. . . .. ~ffect of netnod of colle ction on the composition of in: esta. Discussion. . . . . . Summary EXPE RI 1“};th Experimental Procedure. . . . . . . . . . . . . he ex xperinenta 1 ani imal. . . . . . . . . . . Rations and feeding procedure. . . . . . Collection and Sampllht oroceduro s . . . . . Chemical analyses. . . . . . . Results . The experimental animal. . . . . . . . . . . PartitioI oi digestibility . . . . . . . PhysiolOgica I effects of different rations . Effect of ration and Ira uercy of feeding on the pa ttern of duodenal Iloy. . . . . Effect of ration and frecuency of feeding on the pH of duodenal ing :esta. . . . . . . Effect of ration and frequency of feeding on the passage of in esta from the duodenum . . . . . .. . . . . . . . . . 210 I" O) (N z. F. D- O) (D O) (Y) O) h>- Ui (J4 N“ D" O) .. (\I (\ \j ()3 (‘D (O (0Q \1 (\7‘ (m (0 (\fi LO \7 N (N O O v.. '7;- .A- ‘ ‘ r on. V..._ Effect of eating and rumination on passage Effect of ration and frequency of feeding on the composition of in esta passed from the duodenum. Discussion. . . . . . . . Summary . . TERATURE CITED . . . . . . . . . . . . . . . . . t-« H l KDI' . . . [“I A} 470 " ' v..- “a. a ' I .‘t u " ,_ u a.... bi Va.- ,- ..J\ . u - Q . ‘ - . "Ad 4' V..‘., ‘ . Ivdv A ' F ' -. ~' _ . ‘ g.. -. _ a. ‘ ' o in ..~ ‘1. f . ..... . ' - . O.‘ .. _ o. '0 _‘.\ 'P~ .\ Hug» A 1 ' . v. ‘ ‘. ~ __ . J .. n" . . - A.‘ . s av. . V. -. '.. U a... 'F‘. ~\. :‘V~ ., n. s,‘ ‘ I ._' ‘ . , .I y. I O n h... - r ‘1‘ - .. O.‘I. lA ‘ -:,; ‘~ ‘vu .‘. U‘. A‘ a ‘ . 0‘ I ‘h “a‘ .9 ' a » .- l " ‘ .. ‘&| . . 5“ - --'1 ‘r .‘-‘.I u: . I ‘. ‘U o N- ..‘ I ~.. “,I" Uta t Table [—4 m (V H (D Table Tacle Taole Tatle Table Table Table Table (O 10. 11. lb- vi LIST OF TAB ES Page Chemical composition of feed and feces for pre— and post-surgical digestion trials 20? Coefficients of digestion for pre— and post-surgical digestion trials. . . . . . . b0? Chemical composition of feed for duodenal trials . . . . . . . . . . (V O (I) PhysiolOgical effects of method of collection . . . . . . . . . £09 Effect of no re-introduction on the passage of total ingesta, dry matter, organic matter and ash from the duodenum . . . . . . . . . zen Effect of 15—minute re-introduction on the passage of total ingesta, dry matter, organic matter and ash frdm the duodenum. . 223 Effect of continuous re-introduction on the passage of total ingesta, dry matter, organic matter and ash from the duodenum. . 224 Effect of method of collection on rate of passage and rate of decline of ingesta from the duodenum . . . . . . . . . . . . . 225 Effect of no re-introduction on the quantity of ingesta components passed from the duodenum . . . . . . . . . . . . . 250 Effect of 15—minute re-introduction on the quantity of ingesta components passed from the duodenum . . . . . . . . . . . . . 250 Effect of continuous re-introduction on the quantity of ingesta components passed from the duodenum. . . . . . .. . . . . . . . . 251 Effect of method of collection on rate of passage and rate of decline of ingesta components from the duodenum. . . . . . . . 252 , . ..~.v I o.- I '~- - ".1 .- ‘Lc (J) I l (‘1 o P . (I) r (7' (7' I ‘1 F3 ED (3 F" (D t- 'i 0) (3 F4 (D H m U Fl (D able F? +1 m (T F4 (D F! m 0 Fl ('0 Tesla Tacle Table 15. 14. 13. b0. bl. b5. b4. b5. b6. L7. vii Summary of effect of method of collection on passage of ingesta frOm he duodenum . Average daily intcme of ration components Output of ration components from the duodenum over a ze-hour period. Average daily output of ration components in the feces. . . . . . Coefficients of total digestion . Coefficients of digestion for the upper gut . . Coefficients of digestion for the lower gut . . Percentage of total digestion occurring in the upper gut. . . . Percentage of total digestion occurring in tile lOI’L:er Eu t o o o . o . . o o o . o a Coefficients of digestion for residues entering the loner gut. . . . . . . . . . Summary of physiological data for each duodenal collection Effect of all on the passage of total ingesta, dry matter, organic matter and ash from the duodenum . . . . . Effect of Bel on the passage of total ingesta, dry matter, organic matter and ash from the duodenum . . . . . . . . . . Effect of Ram on the passage of total ingesta, dry matter, organic matter and ash from the duodenum . . . . . . . . . . Effect of R51 on the passage of total ingesta, dry matter, organic matter and ash from the duodenum . . . . . . . . Page m5? b7la Z7lb E72 275 £77 301 304 307 510 , u . ~ “I" ~v~ a. pa. .5 -h-. " ¢- . . .. . 5. 'II 1' _..~ .0... P~ .‘ ~u.. ‘. _.‘ 2‘ _ . u. 1.. “‘.' -'_ .-.. '5‘ t ‘ -- ;. _..; an 4.. a... .~1 —'~‘ .‘ ‘ .‘ ‘\ '. . . I «c.120 -..‘ '. do ' III . .. ~ I "‘J o. .. 5. V4» 2; q . .. “v4“ . Table Table Table Table Table Table Table Table Table Table Table Table 55. 56. 57. 59. 40. 41. 4:. viii of total matter and Effect of R52 on tie passage ingesta, dry matter, organic ash from the duodenum . . of total matter and Effect of R41 on the passage ingesta, dry matter, organic ash from the duodenum . of tota matter and Effect of R4; on the passage ingesta, dry matter, organic ash from the duodenum . Effect of ration and feeding on rate of passage of ingesta from he duodenum. . Effect of ration and feeding on rate of decline of ingesta from the duodenum. . Effect of eating and rumination on passage of ingesta from the duodenum. . . Effect of Rll on the quantity of ingesta components passed from the duodenum Effect of Rbl on the quantity of ingesta components passed frOm the duodenum . . Effect of Rafi on the quantity of ingesta components passed from he duodenum . . Effect of R31 on the Quantity of ingesta components passed from the duodenum . Effect of R52 on the quantity of ingesta components passed from the duodenum . . Effect of R41 on the quantity of ingesta components passed from the duodenum . . Effect of R42 on the quantity of ingesta components passed from the duodenum . Effect of ration and feeding on the rate of passage of ingesta Components from the duodenum. . . . . . . . . . . . . Effect of ration and feeding on the rate of decline of ingesta components from the duodenum. . . . . . . . . . . . Page 515 C21 F" O) 519 5bb 525 550 555 554 555 556 557 558 54; 545 . v o.;~‘ " . I “,‘ 4 H... “I a V; ‘ 0.... '4. n I c . ML; .. . v: . .1... U! -. . c ' " ‘ ' v. . ‘ ~ ‘ . '--.' f . I u». m x ‘. ' v , ‘u u I' '~ ."~ :- . , -. s ‘3‘ a . '1 ‘V. t I. '0 ‘ I“: §‘. h‘ ‘<- ‘ I \ ‘. ‘. \- u; " . ‘ ‘A~ I . 5' X \J. a‘ . ‘ .N‘ ; 1 ‘ \“ v 'u_ '-l‘- . - ‘ Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure 10. 11. la. l5. l4. ix LIST OF Fl GUESS Pathway of carbohydrate constituents in the alimentary tract. . . Pathway of nitrOgenous compounds in the alimentary tract Design of duodenal cannula and external collar. Relative position of re-entrant fistula in alimentary tract. External location of re-entrant fistula with U—tube in situ. Construction modifications (right side elevation) of collection stall Detail figures of collection stall modifications. . . Construction details of plexiglass collection tube and re—introduction tube Collection tube mounted in hangar of carriage . Complete assembly of collection and re-introduction apparatus. Re—introduction with funnel and tube mounted in carriage stirring motor in situ Collection and re-introduction apparatus connected to duodenal cannulae . Position of apparatus with animal at rest. Experimental animal approximately one year after establishment of the fistula. Effect of no re-introduction on the flow of ingesta from the duodenum 150 174 177 179 184 187 189 191 194 198 .- - ,,... .v' ,. .n-I ¢ ' .. , - . nu: 0-,0 . "“ orb. - .I o‘l- .". . .‘. w ;L' on! . II, ~u. ‘ - . ' 5“ l,. ’. ~~o ‘ x q,. L J I ‘- .- . r v- N. D ; '- . a “ a.- &‘. ‘ ‘\ I ’ ‘. K I .. .~ . ‘ V- ‘6 Von - Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure 17. 18a. 180. 18c. 19. b0. 24. 25. Z7. Effect of 15-minute re-introduction on the flow of ingesta from the duodenum. . Effect of continuous re-introduction on the flow of ingesta.from the duodenum. . . Effect of no re—introduction on *he pd of ingesta pessed from the duodenum Effect of the pi of 15—minute re-introduotion on irgesta passed from the duodenum Effect of continuous re—introduction on the pH of ingesta passed from the duodenum Effect of 311 on the flow of ingeste from the duodenum . . . . . . . . . . . Effect of Bel on the flow Oi ingeste from the duodenum . . . . . . . . Effect of Bee on the flow of ingeste from the duodenum , . . ' Effect of 851 on the fiow of ingests from the duodenum . . . . . . . . . . . . . . . Effect of 352 on the flow of ingest: from the duodenum . . . . . . . . Effect or R41 on the flow of lhiestg from the duodenum . . . . . . . Effect of R4z on the flow of ingesta from the duodenum . . . . . . . . . . Effect of ration and frequency of feeding on the pH of ingesta passed from the duodenum . . . . . . . . . . . . . . . . . Effect of ration and frequency of feeding on the output of organic matter and ash from the upper gut . . . . . . . . . . . . Effect of ration and frequency of feeding on the concentration of organic components in the ingesta . . . . . . . . . . Page z14 £16 eel bbl 541 351 +1! 93 (‘2' FJ ( D Q) 03 Influence of no re-introduction on the volume, pH and composition of ingesta passed from the duodenum . . Influence of no re—introduction on the volume, p3 and composition of ingesta assed from the duodenum . . . . . . . Influence of 15—minute re—introduction on T the volume, p5 and comoosition of ingesta passed from the duodenum . Influence of lo-minute re-introductizn on the volume, p€ and composition of ngesta passed from the duodenum . . . . . . . . Influence of continuous re-introduction on the volume, pi and comoosition of ingesta passed from the duodenum Influence of continuous re—introduction on the volume, pi and composition of intesta passed from the duodenum . . . . . Influence of no re—introduction on th volume and composition of inpes 2 passed from the duodenum. . . Influence of no re-introduction on the volume and composition of ingest? passer from the duodenum. . Influence of 15—minute re—introduction on the volume and composition of ingesta passed fron the duodenum . . . . . . Influence of 15-minute re—introduction on the volume and composition of ingesta passed from the duodenum . . . . . . Influence of continuous re—introduction on the volume an composition of ingesta passed from the duodenum . . . . . . . . . 47L 475 H3 \7 (D #5 \7 \7 @- .\) (U ’13 (T) O 481 . . 0 $6.. ...‘ ~ . 9 o... v _ - -50‘ fl xv“ -__' v y. .lo. . v.- - -.,. 5-. ‘- -— u ‘3. . . “ V-‘ - v ‘. ('1 O) (O H! Xil Influence of continuous re-introduction on the volume and composition of ingesta passed from he duodenum. . . . Composition of the experimental feeds and rations . . . . . . . . . . . . Influence of ration and -eeding on the composition of inLesta passed fro” the duodenum. . . Influence of ration and feeding on composition of the feces. . . Influence of 311 on tie volume, p? and composition of ingesta passed from tde duodenum. . . . . . . . . . A composition of ingesta passed from to. duodenum. . . . . . . . . Influence of Rsl on the volume, OH and e Influence of Re; on tn‘ volume, pH and composition of in: esta C:pa ssed from the dUQdGHUL‘u 0 Influence of 351 on the voL me , pH and composition of intesta passed from the duodenum. . . . . . . . . Influence of Rdz on the volume, p? and composition of inpesta passed from the duodenum. . . Influence of R41 on the volume, p; and composition of ingesta passed from the duodenum. . . . . Influence of 34; on the volume, p3 and composition of ingesta passed from the duodenum. . . . . . . . . . Influence of fill on the volume and composition of ingesta passed from the duodenum. . . . . . . . . 5.. xiii Pace Table 5. Influence of Bel on the volume and composition of ingesta passed from the duodenum. . . . . . . . . 508 Table 19. Influence of Bee on the volume and composition of ingesta assed from the duodenum. . . 509 Table b0. Influence of 331 on the volume and composition of ingesta passed from the duodenum. . . . . . . . . . . . . . . . 510 Table Ll. Influence of REE on the volume and composition of ingesta passed from the (3.1.10 (filer-$1.11“ 0 . o o o o o o . o o . o o o o 511 Table 2". Influence of 341 on the volume and composition of ingesta passed from the duodenum. . . . . . . . . . . . . . . . 51b Table Lo. Influence of Rab on the volume and composition of ingesta passed from the duodenum. . . . . . . . . . . . . . . . 513 It I am.-'v fr: 1 . . -1 ,Jl:‘-fq—‘ mn..uhvuh u 2": T fvn: 9-.‘7'. “av _ w . '9-1;:: a: "4..-. d, ":'~nl {'- -A-;'.'D .1; "!.:'I 6 a... ca... D .YJ. ”‘50“ ‘l "‘ 631.. Q~‘ ’ ‘u Q 4 a h ‘o_:.. .'h\\ o.“ , "w. Q N. I A“ a... .‘b d.‘- 5 'fl .." 5;-” -.. 3‘ :: ‘I§.‘ “‘-“.'.£° \- J 1.. {fl . M” , ‘i {vizi- “‘q ‘\‘. ’ ‘i I:' “I a “‘19 ” t 3‘ ‘ I \‘A: 0 " ‘53": r. m. n': a: ' ‘0 HE a N ti I" .' I. “:5 -I‘P‘ ‘4..‘n‘ v . ‘pg .2 INTRODUCTION Anatomically the ruminant alimentary tract greatly dif— fers from that of other mammalian species. Corresponding differences in digestive activity exist which seem to be largely quantitative rather than qualitative. Considerable progress has been made in assessing many of the chemical changes in the stomach; however it has become increasingly important to assess the meaning of these changes quantitative- ly in order to understand their biolOgic and economic signifi- cance. Such measurements are difficult to make. It is un- likely that they can ever be made with the same precision as, for example, the measurement of energy balance of the whole animal. Thus, the need often arises for the substantiation of various digestibility data by independent methods. The same complexity which sets the ruminant apart from other species necessarily imposes a large number of investiga- tional problems that are difficult to resolve. In the reticulo-rumen there occur, often simultaneously, the process- es of intake, passage, absorption, fermentation, addition of saliva, synthesis and, possibly, the transfer of substances through the rumen wall from the blood. Further complications arise from the heterogeneity and stratification of the rumen mass. As a result representative samples and time-sampling relationships are difficult to obtain on a quantitative basis with any degree of certainty. Again, the extent to which a I“ o A“ :75. Cutofi I]. p 03‘ ,3... ... . . .l I v' v HP :0;.-.‘."‘ h 23594. C ;"I:I. r I llv a.“ ~o‘ Veg! 0A - "I“... .I‘ v... " ‘WI- "'1 =USJ.L .,o' . ' v0...» c L “t-uzu .‘ J'Nw'pl,‘ .l‘. I..:* ~-',,:3. SAN . h“ J . It '9‘ .uJ Cck,‘ .“. r», ‘K‘ S h R t... 0 n m. 3' “"9 Q L.” :0. ' I ":5 D“! e ‘ v .I. ‘ (1' '. :H I «.21? § 3.. ‘\,.:’1 I" . ‘ (I .0 A u A v *3: . ' ‘99:)!“ c“ a U n. u. ‘ given coefficient of apparent digestibility in the reticulo- rumen will reflect processes other than those of breakdown and absorption will vary with different analytical fractions of the feed. Coefficients for the carbohydrates (nitrogen-free extract and crude fiber) would be almost entirely due to chemical breakdown. On the other hand a coefficient for nitrogen would indicate a balance of the processes of break— down, absorption of ammonia and the addition of urea in saliva or through the rumen wall. This balance would be influenced by microbial synthesis of nitrogenous compounds from simple nitrOgen sources. Balances for water, mineral constituents (ash) and ether extract would be subject to similar complica- tions. The complex nature of rumen balances has been empha- sized by all who have attempted them. Until recently the only estimates of the extent of diges- tion in the reticulo—rumen were those based on the lignin- ratio technique applied to samples obtained from fistulated animals by complete removal of the contents, from ligated seg- ments of the gut of slaughtered animals and from the reticulum in close proximity of the reticulo-omasal orifice of fistu- lated animals. The use of re—entrant fistulas in the proximal duodenum to directly measure ingesta passing from the stomach appears to offer a more precise method for obtaining quantita- tive measurements of the disappearance of food from the ali- mentary tract and of the appearance of synthesized products x- rt. L3 0 C. 5); . a- T! ~‘::"'-". ’11 ,.n.. In" era-«a 'c a“ .u-no'i' ‘ “" o | mag-:6 ' S ‘Ii-'." - ’ ‘ .l ‘ .n 753' a. Afoi.~ :‘ ‘.:t., “ca- ‘0: v '1 - ~ v;l.‘u I. a? c § ‘§' ot- va'o . . $3931.22 5 I. . 'Ezl‘l§.*‘ H “'d a: ‘gu a . ‘e‘.?3' t': Wage or a, . do? u . ilk-1“ “ “ant? that are not digested or absorbed before they reach the small intestine.f Although it is a matter of conjecture as to which technique is more reliable, it is generally felt that a direct measurement is preferable to a calculated measurement. In view of the limitations of other methods in quanti- tating digestion in the alimentary tract this study was under- taken in an attempt to (a) establish a successful re-entrant duodenal fistula in the bovine, (b) develop a satisfactory method for continuously collecting and sampling ingesta from the stomach during a normal digestion cycle without percept- ibly upsetting normal physiologic relationships of the animal, (c) quantitatively partition digestion in the upper alimentary tract from that in the lower tract and (d) study the rate of passage of ingesta through the alimentary tract, tagether with some observations on the effect of the physical makeup of the ration. ,,O..‘ N' I ’ E ma bvbgv-‘O O r' r7r‘eu-‘v r- - .uv nut..- Vt, no \ , rn‘ RI ~-I- nick “v u ‘4 . ‘5':- 1 . "M, ,,A h ‘ 1 .- n‘ 'o- ‘“" ”glow. l' i. O ‘l H I 2" v f- v ~ I‘ ”" ‘1‘...»‘. r-.. ‘.-\' o. L ‘ I' ‘ “0-. by... -- ‘ . . . - "5-3: .21' “‘r _ wvyu b". .5 ., ' 4. ;: :‘W ..- u UJV“ .“_- 'I e .' 'N . a" s“: “n... v ,. . l~- .. .:L M . '“vn. “v- A J ..t,. ." T;';.J,. .__ N.» p Al ‘ ‘ ."‘ it"; . Q». . ‘ ‘ I“ n . . s3. . REVIEW OF LITERATURE Anatomical Considerations of the Alimentary Tract The anatomical arrangement of the ruminant intestinal tract does not differ essentially from that of other animals (Martin and Schauder, 1958; Grossman, 1955). On the other hand the ruminant stomach is compound and consists of four compartments —— rumen, reticulum, omasum and abomasum. Some regard each compartment as a separate stomach and designate them as such numerically. It is erroneous, however, to con— sider the ruminant as having more than one stomach. Again, the rumen, reticulum and omasum are sometimes regarded as esophageal dilatations because their mucous membranes are nonglandular and their epithelial linings are of the strati— fied squamous type. Embryological studies of the development of the ruminant stomach (Lewis, 1915; Pernkopf, 1951; Martin and Schauder, 1958; Lambert, 1948; Warner, 1958) leave no doubt that the rumen, reticulum and omasum are of gastric origin. The often repeated but superficial statement that they are diverticulae of the esophagus has no anatomical or physiological basis to support it beyond the fact that their mucous membranes and epithelial linings are atypic of gastric tissue which as Bensley (1902), Pernkopf (1931) and Lambert (1948) point out, is no criterion on which to form an opinion. Available evidence is that the complex stomachs, such as those Jo}, as“ ‘B' Q be u“ . on. 5:25: by pf‘f , . A ‘ It. I b :39 5'. 3". a the :1 9":“'t-, ‘05-..‘ _ ’ "a sh»! ‘fib U U- .. a " a“ w b “y. I My a ‘ 5-- 5“; In ‘6.“ I.‘ ‘4 in" “I . «1‘33 t— E" .‘l'? 55‘: 0" s, '1“e Jo of the ruminants, rodents, etc., are produced from a simple stomach by prOgressive phlegenetic specialization, in which the esOphagus takes no part, and in which the important phenom- ena are the suppression of the gastric glands and the replace- ment of the muci-genous epithelium by a stratified squamous epithelium- The stomach of the domestic ruminant does not differ in its early developmental form from the simple stomach of other mammals. The first sign of develOpment is a spindle-shaped dilatation of the primitive gut whose dorsal edge is situated with its longitudinal axis. This dilatation is characterized by a bulge toward the left side due to rotation of the stomach and by the appearance of right and left longitudinal grooves which are separated from one another in the stomach cavity. Rumen, reticulum, omasum and abomasum all develop concur— rently from this dilatation at a later stage; the rumen, reticulum, lesser curvature of the omasum and the principal part of the true stomach develop from the left longitudinal groove, while the esOphageal groove'and the lesser curvature of the true stomach form from the right longitudinal groove. The sac-like omasum empties out between these latter struc- tures. According to Lambert (1948) the initial appearance of the spindle-shaped dilatation takes place in the 7 mm. embryo. In the 9 mm. embryo the area of the developing eSOphageal groove can be seen along the concave lesser curvature and the ‘ «6' '9“'€8 131 3:25 mien bee: :efizite areas 2:22 that t" .25 3C 2'. 6'." 321.1: occur ' 31"";- ‘ ’t. IJrg.“~O .‘. '1 '3‘;‘ the 'un. g”. {1 ii) In. ‘ a -... days a 35:: man , " ‘Hrgfi‘ ‘ 'x-v‘. ““‘3 31338: .‘5.:I A. " 0...Y ‘1. ‘ ere: 3')“ A '1 O ‘I c’niin' I. I" . “t at *1“ 1“ 4.“ o "‘H ““ ”“54 ‘ § ‘1‘?“ ‘e ‘ ' WC! w : ‘ .‘ a ‘v «‘5 or +)'\ M“! ii'\ NM ‘ " rumen becomes larger than the other compartments. Prominence of the rumen becomes even greater in the 14 mm. embryo and indefinite areas can be apportioned to the omasum and abo- masum. All of the stomach compartments are differentiated in the 30 mm. embryo. This was determined by Becker at g;. (1951) to occur by approximately the 59th day of fetal develOpment. These workers further observed that the rumen dominated the net weight of the other stomach compartments up until 120 days of age. Thereafter the abomasum begins to in- crease rapidly in size. Hix (1954) found the tissues and vascular system at 175 to 195 days of development were com- pletely differentiated and wellpdeveIOped and the prOportion- ate size of the four compartments was approximately compar- able to that of the adult ruminant stomach. The abomasum, however, continuesto develop rapidly and is the largest com- partment at birth, comprising approximately 65 to 70 percent of the total stomach weight (Becker gt gl., 1951). Martin and Schauder (1938) indicate that formation of the mucous membrane of the ruminant stomach precedes that of the folds of the abomasum (22 mm. bovine fetus). This is soon followed by development of the omasal laminae, then the retic- ular ridges and finally the rumen villi. Only the abomasal membrane appears turgid and ready to function in full term fetuses according to Becker at al. (1951). Excellent, detailed accounts of the embryological devel- .9 t J 7 N. F 93“» 8»- ’I ‘1 b LgLean 1 a--ll v\ VH‘O". '9 -‘ O.vuiy .“ ‘5‘.” 4 ~- ‘4 :«b.. .16.: e .1 n) - It - b $.‘ ' 85.”: h. ‘ a tec.e ‘5‘ . . ‘52.,2114 ‘ L, .'" n “A9.qfi ‘1 opment of the ruminant stomach are given by PernkOpf (1951), Martin and Schauder (1938), Lambert (1948) and Warner (1958). Data obtained by Duncan and Phillipson (1951) on the fetal lamb and by Parrish and Fountains (1950, 1952) on calves slaughtered at birth show that considerable activity occurs in the alimentary tract before birth. Suckling and swallowing movements were observed by Duncan and Phillipson to occur from the 80th day of development with the swallowed material being distributed in all parts of the stomach. Complete passage of the suckled fluid to the abomasum did not occur, however, until 131 days of age. Parrish and Fountains found large concentrations of hair in the lower colon as compared to that of the stomach or of the small intestine and concluded that considerable material had passed through the alimentary tract and that absorption had occurred. The rumen, reticulum and omasum are small and essentially non—functional at birth in comparison to the abomasum in the three species (sheep, goats, cattle) that have been extensive- ly studied and the general pattern of development in animals on similar dietary regimens is likewise much the same for these species (Sisson, 1923a, 1925b; Lagerlof, 1929; Martin and Schauder, 1938; Grossman, 1948; Becker 2; g;., 1951, 1952; Benzie and Phillipson, 1957; Tamate, 195e, 1957). In the newborn the rumen and reticulum are confined to the left dorsal part of the abdominal cavity and the rumen t“ ‘Wna‘ ‘ '41‘l .‘n ~‘JVP3E (V‘Ig': 211911231 253:: is 51 [‘5’ .H ,‘r 4"! u. ‘0. b E? h” Eu Feb. “5. 0',” A, 5.“? “"5“ U“ 1'. .' C . 4 0:5. :"‘e ex I.‘ k 2'9.’ H u"v‘-i.‘. 2'33: la 3“!) c "In Me ‘v size 1 #4 V“ 7“ 3H (.1 a ‘ 1’ 'I ' "I "‘J'L‘t and only extends as far back as the first lumbar vertebrae. The omasum is situated to the right of the reticulo-rumen and is much higher in position than later; the lesser curvature is ventral. During this early stage the abomasum, which occupies more than one-third of the body cavity, is situated on the left side extending from the diaphragm to the caudal third of the abdomen. The intestines are chiefly located in the left half of the abdominal cavity. As the stomach develOps the rumen gradually extends ven- trally, caudally and laterally along the left side and even- tually occupies between one-half and three-fourths of the abdominal cavity. Lateral extension of the rumen moves the abomasum and intestines to the right of the median plane. The reticulum enlarges and moves the body of the abomasum caudally away from the diaphragm. DevelOpment of the omasum appears to be slowest of the four stomach compartments and is character- ized by a gradual rotation ventrally so that the lesser curva- ture in the mature animal assumes a dorsal-medial position. Final position and development of the rumen, reticulum and omasum does not appear to be attained until the animal is eat- ing considerable quantities of solid food. The abomasum in- creases in size at a much slower rate than the reticulo-rumen and finally is found entirely on the right side of the body and in the epigastric region of the abdominal cavity. The intestines are situated, for the most part, in the right meso- z; " "“t 83:. . IIOEN 1‘ l A “:9 6?“ n='"""( 0 . u .o'vb-u .1 : Oh. I .13. .J. :51. he I.A* Oq J‘t'h. w- h v. v. v r ‘ I. 1 . 2:; 3pm ‘ anti '3'. fill. 0‘,‘ ,!§ 1 uni “5" . I but" 7‘ 1" H““.." L: o “3" w l / :FR 3‘ -: 4“ uAa‘ _- p 2. v ‘.'M "' "H"! 3.99) V), . A: "“ 391.82 w I:.-. . '1‘“ 118 o: .1: fig «.9 rECI )3" ,. ."V?‘.ilil ‘Fl‘n (1“055 'C I“ -. g "2: .. .‘N. "e ~‘ I! 1 k" K. 25” '4‘: 'I hEU (194‘ ‘- ftfitaF ‘A‘ MU. 8" Y’- “d I.,‘ ‘. ‘ltk:“ 1. J t" V ‘ ‘ |. ’ t I‘n‘ I'I and right and left hypogastric regions of the abdomen. The importance of diet as a factor influencing post-natal develOpment of the fore—stomach compartments has been recog- nized for many years. Subsistence solely on milk diets has been shown to retard deveIOpment of the rumen, reticulum and omasum (Trautmann, 1952; Blaxter gt gl., 1952; Warner g3 g1., 1955, 1955, 1956; Dzuik and Sellers, 1955; Maziere, 1956; Meregalli, 1956; Tamate, 1956, 1957). The data of Trautmann (1952) and Blaxter gt g;. (1952) indicate that although fore- stomach develOpmsnt was retarded with prolonged, exclusive milk feeding, some growth was apparent, suggesting that diet was not the only factor responsible. This observation has been more recently confirmed by Warner and co-workers (1956). McGandlish (1923) observed that the mucous membranes and papillae were normal for calves which received both milk and grain though the musculature was not well developed. The pro- found effect of grain on papillary development and tissue deposition has been demonstrated more recently by Brownies (1956) and Warner gt 5;. (1956). Grain was also reported by Hastings (1944) to cause normal rumen development, but no ex- perimental evidence was presented. Many have believed that roughage is essential for proper development of the first three stomach compartments (Ausrn- heimer, 1910; McCandlish, 1923; Lagerlof, 1929; Magee, 1952; Blaxter g§,g;., 1952; Dziuk and Sellers, 1955). Blaxter and routers ( 1.. .e‘V o . ' In! I- 0“ 9.15 I I; “n :22 3c 1.... :°' . n-v {ihEt can ¥ v u .. 1’ .2!- IF“; 0 H:: A ‘N V we. a I ‘u. «- 32 2111» V‘. a“ F.— “ ~y'cutlfu :‘Ql: ~ “6-1 '36:) "'5: I "f" $5 in ‘ 3' I Q e Eh!“ r. "ed' 10 co-workers (1952) reported that roughage ingestion consider- ably increased the capacity of the rumen, reticulum and omasum. Since no increase in tissue weight was observed, it was assum- ed that roughage had increased the capacity of these compart- ments merely by stretching the tissues. The response of the rumen wall of roughage-fed calves to vagal stimulation was observed by Dzuik and Sellers (1955) to be more marked than that of milk-fed calves. Greater regularity and amplitude of both spontaneous and stimulated contractions of the rumen in roughage-fed calves seemed to indicate that the presence of roughage in the fore-stomach compartments served as a stimulus for promoting greater rumen motility as well as for promoting anatomical development. Trautmann (1932) demonstrated that the structural devel- opment of the pillars, compartments and papillae of the rumen did not require roughage. His work clearly indicated, however, that including roughage in the ration increased the size of the fore-stomach compartments, the degree of papillary devel- opment and the amount of elastic tissue present in the rumen mucosa. Later studies on the extirpation and regeneration of the rumen and reticulum (Trautmann and Schmitt, 1952) and of the omasum (Trautmann, 1933) suggested that feeding roughage soon after the operation considerably hastened the regenera- tion process. ‘ The more recent work of Warner 23.21. (1956), Brownlee \ ...' e . :‘n "q . I 1 CNN] "” N". ’("A"_‘ Lug. . fiends“: - ...,- “(n-put .l'::e volt!“ .401 D, :...:222..y ac " "'1' Li ' I IIqG‘ .e "e “9 8 2 1‘85 1E“ errecel. 211:9 papil' L9L‘:l we. 11 (1956). and Tamate (1955, 1957) substantiates many of these earlier findings. From the data presented in their studies it was evident that dry feed (hay, grain or hay and grain) considerably accelerated develOpment of the reticulo-rumen and omasum. Little change in the abomasum, however, was ob- served as a result of the radically different diets. Grain- was as effective as hay in stimulating the early growth of both the papillae and tissue of the fore-stomach compartments, while milk was ineffective. Thus, it appears that dry feed pg; gg was essential for this development. Roughage, because of its greater bulk, increased the capacity of the fore- stomach compartments but, as such, did not appear to be a dominant factor in development of the rumen papillae. The evidence strongly suggested that chemical entities rather than coarse materials were largely responsible for papillary growth and tissue deposition. Much of the earlier research which reported the relative capacities of the various stomach compartments with increases in age has been summarized by Auernheimer (1910) and Martin and Schauder (1938). Diet was not controlled in many of these experiments even though its influence on the structural changes which took place was recognized. The data show a gradual increase in the proportion of the total capacity occupied by the reticulo-rumen. Combined capacities of the rumen and reticulum were calculated to be 0.3, 0.5, 0.67, 1.5, .égn;‘n~ l': ‘oun...: 13:25 25th 12 2,24 and 4 to 6 times as large as the abomasum in calves at birth, 4, 6, 8, 10 to 12 weeks, 4 months of age and in adult cattle, respectively. These results are in good agreement with those obtained by Kesler gt g1. (1951) for calves and by Tamate (1957) for goats. The data presented by these workers indicate, as do the findings of previous authors, that the most rapid change occurs between 4 and 8 weeks of age and corresponds, for the that part, to the period immediately following removal of milk from the diet. In addition, the ratio between the capacities of the reticulo-rumen and the abomasum become reversed at approximately this same time. Thereafter development of the rsticulo-rumen and omasum proceeds rapidly toward maturity. lagerlof (1929) used transverse sections to show that the rumen of normally fed animals had attained its final relative size and position in 9 months although at 3 months of age it was not strikingly different from that of the adult. Gross- man (1949) indicated that approximately 4 to 6 months were required for the stomach compartments to approach adult pro- portions; final relative oapacities were not achieved until 1.5 years of age. f Most of the information on the capacity of the bovine stomach which can be found in anatomy and physiology texts is primarily based on the early investigations of Schmaltze (1894) and Colin (1886). In these eXpsriments the stomach, had been I 12:22 via the es 1111211 per .5 ‘4 mad and se; ‘ \‘l n; 0..“ :hlfifiesu .5. I... dig- 23‘:1g :3? if ”5"“ co: "4 :2. 13 which had been removed from the body, was filled with tap water via the seephagus or duodenum. Water was introduced until all parts were elastically stretched and no further splashing could be observed. The various parts were then ligated and separated from each other. The reticulo-rumen and the abomasum were drained and the contents measured. The omasum was immersed, undrained, in a graduated receptacle and the displacement determined. The results obtained for the omasum thus included the displacement of its walls and laminae, which is not insignificant, as Blamire (1952) and Makela (1956) found the average weight of the empty omasum to be about 10 pounds. In cows and steers the capacity of the reticulo-rumen ranged from 21-53 gallons. The average of the largest animals was about 42 gallons. Older animals of medium size had a capacity of 26 gallons while small animals had a capacity slightly less than this. The capacity of the reticulo-rumen of adult animals considerably exceeded that of young animals of equal weight. Cows similarly had a greater capacity of the reticulo-rumen than steers of the same size and age. The omasum of adult cattle had a capacity of 1.8 - 4.8 gallons; the abomasum had a capacity of 2.1 - 5.8 gallons, Colin (1886) as well as Grossman (1953) report figures for the capacity of the stomach compartments in cattle that are somewhat higher than those given by Schmaltze. zglayed by Sc iefizite over; J . "e m r. t l..— "M Mir; U | Nchn. of 0. :fi!: ‘ 456». “yet ”I.. s‘::‘ \gap \ 1'“ a ‘eéw‘ " a ‘ - I. ...q‘ 14 Paloheimo (1944) used essentially the same method as that employed by Schmaltse but filled the stomach compartments to a definite overpressure (5 cm. and 10 cm.) of water. The ratio of the rumen capacities varied between 1.15 and 1.28 at 5 and 10 cm., respectively. In both instances the values obtained by Paloheimo considerably exceeded those obtained by Schmaltze. This suggests that the stomach compartments are quite elastic and infers that considerable variation in the capacity of the stomach can be obtained merely by varying the degree of over- pressure. Schmaltze introduced so much water into the stomachs of 10 experimental animals that the walls showed signs of in- cipient rupture. In this way the reticulo-rumen of large animals could accomodate as much as 72 gallons. Similar re~ sults were obtained by Paloheimo by employing an overpressure of 15 cm. of water. Thus one might deduce that the cow's ability to fill its rumen with feed is not so much limited by the capacity of the rumen, as by the volume of its abdominal cavity. 'Although the values obtained by filling the detached stomach with water give an estimation of ”absolute” or max- imum possible capacity they do not, by any means, express the stomach capacity of the intact animal. "Physiologic” capacity appears to be a more applicable term and is defined as the highest degree of fill which can occur in the alimentary tract or its parts while the body still functions quite may. To e? 9.3:! in the pa." linearized 13 «i for an ads: Tue menu: Thee: invest: "3.2:: w“ , I E‘J'¢p-! v ‘wll. {Aged may in». , F ‘9‘ “L .I‘q, ". ‘E: “a II‘3 ‘1‘». z. ‘ h a "E ' 03w .5 h- 15 normally. To establish this characteristic the amount of in- gesta in the part of the alimentary tract under consideration is determined immediately after the animal has been on full feed for an adequate period of time. The quantity of ingesta in the bovine alimentary tract has been investigated from time to time in connection with various problems, however, the amount of feed offered to ani- male in such eXperiments was generally limited so as to insure a constant daily intake. As a result the amount of ingesta will hardly be equivalent to physiologic capacity. In their investigation on the rate of passage of food through the ali- mentary tract of steers, weighing from 796 - 847 lbs., Ewing and Smith (1917) fed one 23 lbs. of silage and 3 lbs. of cottonseed meal, another 15 lbs. of silage, and 4 lbs. of cottonseed meal and a third 23 lbs. of silage per day for a prolonged period of time. The amount of ingesta in the entire alimentary tract was 144, 142 and 156 lbs., respectively. Assuming the reticulo-rumen contained, on an average, 70 per- cent of the contents in the alimentary tract at any given time (Natale, 1956) the rumen ingesta would have weighed approxi- mately 103 lbs. Novena (1928) fed three cows weighing between 1056 and 1276 lbs. up until the time of slaughter on the following rations: 665 - 26 lbs. hay, 0.4 lb. corn, 738 - 25 lbs. hay, 19 lbs. corn and 12313 - 15 lbs. hay, 15 lbs. corn. Hay was :1; 2m, 1 it 539 C33! ‘0- o:“an‘j e 5' .40‘001 ...s.' 9‘ :1?! .QFVCF . ‘h' r3” 'Uea- v mfll‘e (:3 j ."- “Ever: ':‘.. Lhéta‘ “f“... C: ’4‘.” v .Un ." .l J "i, “ 2 0 Q . K51 A] s ‘u. .‘H- ‘ "NW e]. 'I (an. I" s - ‘Vq r“ v! .. :‘:--“-‘ Hi‘ue‘v ‘. ‘ r i “he I.“ “an. l6 fed daily during a preliminary period whereas corn was fed only once, 1 - 6 hours before slaughter. The reticulo-rumen of these cows contained 103 (13 lbs. dry matter), 109 (24 lbs. dry matter) and 106 (21 lbs. dry matter) lbs. of ingesta, re- spectively. Rumen contents, on a fresh-matter basis, were about the same in all three cows irrespective of the ration. A comparison of the first two cows shows that the large amount of corn fed shortly before slaughter did not essentially in- crease the quantity of ingesta in the rumen but did have a remarkable influence upon the amount of dry matter. Blamire (1952) determined the amount of ingesta in the various stomach compartments of 77 unselected bovines by weighing each segment full and empty, cleaned but in a wet condition. Some of the animals were fasted but others were deliberately fed pg lip- ,iggm on good quality hay for three days immediately prior to slaughter. Capacities were estimated from the weight of con- tents on the basis that 10 pounds of ingesta occupy a volume of approximately one gallon. Perusal of the data shows that the average capacity.of the stomach was 10.1 gallons. Average capacities for the various stomach compartments were 8.6, 1.3 and 0.2 gallons for the reticulo-rumen, omasum and abomasum, respectively. The highest capacity of the reticulo-rumen was 17 gallons for a cow which had been heavily fed prior to slaughter; the lowest was 3 gallons for a heifer whose total full stomach weight was only 66 lbs. Little difference could 1"9‘1'35 ) I: .I-I. _.v L‘ 32-!“ ii a” .‘IA. A’ l. L ~45 V. I“... l’ ‘F‘I‘ int.- i. L 4 .4. O ‘. . nine. '3 5‘8... '1?“ gl‘va' m.V|1 n. “ L: a .:80 ' It. . on r “53' h: .. _.: u 1‘ :L a nu: .v" . -| "MI... 31.an -. I“ my. I" “ l "I" V 4t 0“ n‘ 5. l‘hw. \ -w.. “ \= :1.M \-“ “1:7 Tn. 'al ls.‘ f n t "1’ "“65 in ' 17 be observed between the estimated capacities for the fasted and non-fasted animals. This finding is in good agreement with that of Nevens (1928). Natale (1956), in studying the effect of bulk in the ration, fed six cows (average weight 1120 lbs.) 22 lbs. or more of hay per day over a lO-day period prior to slaughter. The average amount of contents in the entire alimentary tract was 231 lbs. of which 161, 20, 6, l6 and 22 lbs. were contained in the reticulo-rumen, omasum, abomasum, small intestines, and large intestines, respective- ly. In a number of cows, similar in weight but consuming smaller amounts of hay, the quantities of contents in the ali- mentary tract, particularly those in the reticulo-rumen, were only slightly less than in the cows receiving hay practically ad libitum. Young bulls, 7 months of age and weighing about 450 lbs., which were given hay in an amount nearly equal to the ad libitum intake, had 112 lbs. of ingesta in the entire alimentary tract. The following quantities of contents were contained in the various parts of the tract: reticulo-rumen 88 lbs., omasum 5.5 lbs., abomasum 2.4 lbs., small and large intestine 7.7 and 6.5 lbs., respectively. It is obvious from the various research cited that the amount of ingesta in the reticulo-rumen as well as in other parts of the alimentary tract is considerably less than the amount of water which earlier investigators have been able to introduce into its various parts. As a general rule the con- 2:13 feuzd in ti :ecréer of tag léiiticn the 51.21: on the 1155!; a certs: 11in: :3: see: ments, as 15 r I 1.“ \ 18 tents found in the reticulo-rumen of adult cattle have been of the order of magnitude of 100 - 160 lbs. (10 - 16 gallons). In addition the quantity of ingesta appears to depend only slightly on the level of intake, particularly if roughage makes up a considerable share of the daily ration. Therefore it does not seem too presumptuous to infer that the amount of contents, as is cited, represents the physiologic capacity of the adult bovine alimentary tract and that some revision should be made in the existing, accepted standards of bovine stomach capacity. The Course Followed by Food Through the Alimentary Tract Many cf the physiolOgical aspects of the ruminant ali- mentary tract, particularly the course taken by food materials as they pass through the stomach, have been studied by employ- ing two principal methods: (1) investigation by means of fistulas into the stomach (Schalk and Amadon, 1928, as well as numerous other investigators have used this method); (2) roentgenographic studies on small ruminants after the adminis- tration of radio-opaque meals (Czepa and Stigler, 1929; Magee, 1932; Phillipson, 1939; Dyce, Merlen and Wadsworth, 1953; Benzie and Phillipson, 1957). The pathway followed by various food materials as they pass through the stomach varies considerably and appears to be influenced primarily by the nature of the food material ":3" p55 .Oeeo‘ . ‘ ‘I ..’0‘ INA! ,, penguin] 1 one." "I J I|' 9.0.4.. 0 .- g 1 u" a and I k.l.. “an ”13"‘rcr ' ‘ 'vH'a.‘\ .‘v 2,: 5‘ I"‘ *‘i V. "‘9 4‘ ‘ ,n 3. ‘0. |0Vu “ne‘- 5 he! ‘ I‘”" V‘vn u: u aw.- . an. ;.‘..a flfln‘ ‘9".- § ' "ut' . One. K. V I.) n. y ‘ a o 5. fl '1‘. 8‘0. ‘c“. ‘ n ‘.1 "90.“. “at a: O .‘ . e‘l we :5, U ‘i\a‘ "'7‘ :Q‘! ‘s v“: '{ ‘32Ps“ “ bet " w .‘I \J‘ :6 “ ‘ his 5 lint] §.: 1. ' .I‘c -.‘a 19 itself. Passage of the food is, for the most part, the result of continuous rhythmical movements of the reticulo-rumen. The essential rhythm as described by Schalk and Amadon (1928) for cattle and by Phillipson (1939) for sheep consists of a bi- phasic contraction of the reticulum which is followed rapidly by a contraction of the anterior and posterior pillars of the rumen and of the dorsal sac. At the end of this movement con- traction of the ventral sac and posterior pillar occurs. The double contraction of the reticulum throws the more liquid ingesta contained within it backwards into the rumen. An im- portant phase in this sequence is the damming back of the ingesta by contraction of the rumeno-reticular fold (Dougherty and Meredith, 1955; Benzie and Phillipson, 1957). Reid (1958) has more recently found evidence suggesting that the damming back of the ingesta in the cow is achieved by the anterior pillar rather than the rumeno-reticular fold. The dorsal sac reaches the peak of its contraction immediately after this movement and the fluid in the anterior part of the rumen flows back to the reticulum as this organ relaxes. In cine-radio- logical film Benzie and Phillipson (1957) observed that dila- tation of the reticulum occurs at this point. An extra rumen- al contraction may or may not occur before the next contrac- tion of the reticulum (Weiss, 1953; Benzie and Phillipson, 1957). There is general agreement among most investigators that . ,l ‘ "In! agter . 9 v-- I'd &“ . 33:35.1 5 "t I ‘ ‘ .té. ,rnac I». U u' C'- ‘ " "‘le Pager. Z'iei differ J 1‘" ‘ a “.565 ha f! 3"? remit“ '3 ' ‘Q “I.“ 1.1812 ‘ ‘ :"V' :07 ‘ :6. «5‘0: 8: L's "u x“ h A: '11“ g ".791 I)! 15;: '. v IN Ueco‘E {:6th y “ “5 that :‘4: a 20 food materials swallowed in the normal manner go to the ante- rior dorsal sac of the rumen in mature ruminants. The pathway subsequently followed depends upon the character of the in- geeta. Schalk and Amadon (1928) and Smith g1; g1. (1956) ob- served that coarse hay particles collect in a 'mat' in the dorsal part of the rumen and remain there for many hours. In contrast, grain particles are initially mixed throughout the rumen ingesta after eating, but rapidly settle to the floor of the rumen and reticulum. Balch and Kelly (1951) found no marked differences between the specific gravity of particles of ingesta from the dorsal and ventral sacs of the rumen of cows receiving an all—hay ration but pointed out that the mat itself likely has a lower specific gravity than its particles. Both Balch and Kelly (1951) and Smith 91; Q1. (1956) agree that the fibrous particles which settle to the floor of the rumen are buoyed back up into the mat as a result of gases produced during the initial fermentation of the hay and that these gases become entrapped to some extent in the mat. Thus it‘ appears that hay particles remain in the dorsal sac of the rumen for the most part until, through softening, maceration, rotation and fermentation, they have lost their particulate identity and are no longer large enough to be carried back to the top by gas bubbles. This strongly suggests that rumina~ tion, by reducing the size of the particles, may be of con- siderable importance in hastening the sedimentation of hay gazizles 5m :ii:e:e that 1 3:52: icon :7: "3'12: fed 1! 311295 out tit! “W of 3:1: |I|"| :‘I’ l' 'r due J. t‘le r: W; ' T‘ "'vfiec. *ZE "idir. § ..¢.M'E ‘hat a. N 1" I ‘ )u "- J; #1 ti) 1311:: or r: I.S . .‘ \ m "V w round “at: . .' -“ “uni? ..1p 3 .. .r‘rl ‘~-.,L‘:.n ' ‘NF UL 'i 5‘“. ‘ \.".pr =fl“ a“ '4 Y "L l ' '1' §y39‘ I ‘) I'. 3?. Fr“. . lys c, P M .T“ *\ («,I‘qa “*9!“ ‘ I I 21 particles from the mat. Recent studies by Gordon (1958a) indicate that in sheep the amount of rumination is not de- pendent npon the quantity of roughage ingested, except when the diet fed is nearly roughage free. Gordon (1958b) further pointed out that if reduction of particle size were the first object of rumination then a close relationship between the state of the food and the time Spent in rumination would be observed. That such is not the case was illustrated by the finding that sheep spent more time ruminating when grass hay was ohOpped to approximately two inches in length than when long hay or finely ground hay was fed. In addition Gordon (1958c) found that rumination was independent of any time (relationship with eating except insofar as eating inhibited rumination for a period of time afterwards. The mechanism of rumination has been discussed in detail by several investigators and all agree to the importance of reticular activity in this function (Schalk and Amadon, 1928; Magee, 1932; Downie, 1954; Dukes, 1955; Habel, 1956; Clark, 1956; Webster and Cresswell, 1957). Regurgitation is char— acterized by an extra contraction of the reticulum which imme- diately precedes the normal biphasic contraction. Semi-liquid ingesta is siphoned into the esOphagus and carried to the month by retroperistalsis. The fluid portion of the regur- gitated material is pressed out and immediately reswallowed. The solid material is thoroughly chewed, mixed with saliva and swallowed. 3’- La-si‘; sac ani. . . cl 3; hi re.. use with 11‘. In 33:12:23 25;: way into ;a.=s‘.':e:e iirel t2 the reticui "1.. z . a: qp Pfi' h»: r:-’ ‘ «I iisperse: 222:2 alsuzhte: he “Sully tn c '9. ii ”18' n 1 Lu 22 reswallowed. Remasticated food is deposited in the anterior dorsal sac and, for the most part, passes into the ventral rumen and reticulum. Hay particles appear to follow this course with little variation. In contrast to roughages, concentrated feeds soon find their way into the reticulum and in some instances part may pass there directly. A portion of the concentrates may pass from the reticulo-rumen during the course of the meal (Schalk and Amadon, 1928). Nevens (1928) observed that corn was evenly dispersed throughout the rumen of animals fed shortly before slaughter. The preparation of such material, whether finely ground or shelled, seemed to bear no relation to the path followed in the stomach. He further observed that the course corn followed was essentially the same regardless of whether it was fed separately or mixed with hay. Schalk and Amadon (1928) observed that uncrushed kernels of corn gravi- tate rapidly to the ventral part of the rumen and the reticu— lum and remain in these locations for considerable periods of time. Similar observations have been made by Kick gt g;. (1937). Furthermore, these workers found that the amount of corn fed or the corn-hay ratio had no effect on the time of retention. Grains do not appear to be remasticated unless they are entrapped in the meshes of the roughage (Schalk and Amadon, 1928). As a result substantial amounts of whole and coarsely cracked grains may pass through the animal visibly ‘ h 95:21,: do 0‘ :25: of can] '9‘ g "nflfiun .35.. “up“; \ D. A 1| " :: 'lzrese “ 2111:3131 a: 79221;: of C‘ "“99! J . 5‘") 5‘. 13'. 23 intact. Mitchell gt g1. (1928) found that heavy feeds, which presumably do not enter the rumen, passed through the reticulo- rumen of cattle at a relatively rapid rate. Available evidence indicates that particle size and den- sity noticeably influences the pathway followed by concen- trates through the stomach. Since natural feeds are subject to pregressive diminution in particle size through the gut, alteration in density as a result of hydration or bubble occlusion and alteration in composition through prOgressive removal of digestible components King and Moore (1957) have employed inert plastic particles of varying size and density to study passage through the reticulo-rumen. They observed that the heavy particles (specific gravity 1.42) were found only in the bottom ingesta whereas almost all of the particles of specific gravity 1.09 had been ruminated. It is interest: ing to note that this latter value agrees well with that ob- tained for ingested hay particles (specific gravity 1.04) by Balch and Kelly (1951). Rumination undoubtedly comminutes coarse feeds to a fine consistency. When ground concentrates are fed alone rumina- tion is not physiOIOgioally necessary to the animal. Schalk and Amadon (1928) found that a ration composed exclusively of concentrates abolished rumination. Kick 21 gl. (1937), Ritz- man and Benedict (1938) and Gordon (1958a) observed that, although complete cessation did not occur, rations composed 511391,? If c he“ an cv- 1aliéJn d- L‘La’ ‘"° " P a Buy or. I . ‘ --.~.- n.’ a . ‘0'. I5 u- «I rv-IJ' .‘V a,“ t. .4.“ '4 ..‘ It“ 1,, 5,6 I ' -.see~ .‘J ' ’J‘Cflfle l mu... ' gt’: M"~‘Fa " 'vut. R, I .ge y‘ '9 :- '6‘- ; Q ‘?5?~! :H‘i“‘P I \A. i. I Is:e :2... ' N. ’. l-i: . J-‘ts ‘ r.” en, ._ v 4'- - 24 entirely of concentrates resulted in a marked decrease in Immination and much of this was 'pseudorumination'. Grinding all of the hay in the ration substantially reduces rumination (Kick at g;., 1957; Ritzman and Benedict, 1959; Gordon, 1958b). Kick gt g1. (1937) also found that as the ratio of grain to hay in the ration of cattle increased the amount of time spent ruminating became less. This did not appear to be the case with sheep however, for Gordon (1958a) observed no difference in the amount of time spent ruminating as long as some roughage was included in the ration. The view that water, saliva and soluble feeds, such as molasses, normally pass to the reticulo-rumen of older animals has been generally accepted by most investigators. Schalk and Amadon (1928) observed that liquids may remain within the reticulo-rumen for only a brief period of time or, depending upon conditions, for several hours. The same course taken by solids is apparently followed by the liquids. Studies, in which water-soluble polyethylene glycol was used as a marker, suggest that water and dissolved substances pass from the reticulo-rumen at a faster rate than the solid 'ingesta (Sperber gt g;., 1953; Hyden, 1955). Evidence that the ingesta leaving the reticulum is substantially lower in dry matter than that of the rumen lends support to this premise (Belch, 1957). The importance of liquids in the transport of both the soluble and insoluble residues has been at: out by s: Sui-liquid $319311: 11?) rest orifice, I :31: troughou‘ 1232 as: be a l 22:21 orifice bl 3:111: ingesta l 5.,“ “2.7 A! O‘ I w-nglnuz‘u h .22 course ; 1:: t! ‘ ‘ “5% Been a 25 :minted out by Schalk and Amadon (1928). Semi-liquid ingesta, in which the solid material has been sufficiently divided to allow passage through the reticulo- omasal orifice, appears to leave the reticulo-rumen contin- uously throughout the day. Phillipson (1946) suggested that there must be a constant flow of ingesta through the reticulo- omasal orifice because the omasum, abomasum and intestines contain ingesta at all times. The flow of ingesta leaving the omasum (Bouckaert and Oyaert, 1954) and the abomasum (Phillip- son, 1952; HOgan, 1957) also suggests that passage is rela- tively continuous. The course followed by solids and liquids in the omasum has long been a subject of considerable speculation. Schalk and Amadon (1928) theorized that the semi-liquid ingesta from the reticulum passes into the interlaminar spaces and that a subsequent contraction of the omasum expresses much of the liquid and finely divided particles, retaining coarse residues for further comminution. From a study of the nitrOgen, lignin and dry matter of the rumen and abomasal contents of sheep, Gray gt g1. (1954) could find no evidence to suggest that a differential passage of fluids and solids occurred to any ex- tent in the omasum. On the other hand Bouckaert and Oyaert (1954), by inserting a.special cannula in to the omasum, were able to collect ingesta which had a dry matter content varying between 5 and 10 percent from the omasal-abomasal orifice. "HJq‘O 9 I “060:3.“ .0 L J " v .. :2 3% a _J~‘_ V “a. e, S ‘ 9 . fi.. . t w . st: 9. ‘ n 3“ ‘. Q‘sA .‘h'vr‘ . 0‘- K‘ S: . fl. «(‘9 a 26 This observation supports the concept of a differential pas- sage of the liquid ingesta to the more solid material. It is difficult to understand how the material between the laminae of the omasum (usually between 18 - 23 percent dry matter) is moved through an organ which produces no mucous secretions unless there is a flow of liquid to assist its passage. From the radiOgraphic plates published by Benzie and Phillipson (1957) it appears that as ingesta enters the omasum the superior pole relaxes drawing the material up between the leaves. The organ then contracts and the fluid part of the ingesta is squeezed out and flows into the abomasum together with the more liquid material from the lower pole. Liquids also appeared to pass directly through the omasal sulcus. The fluid expressed from the interlaminar spaces presumably assists passage of the more solid material to the abomasum. Little work has been done in ruminants with respect to to course followed by ingesta through the abomasum and intes- tinal tract. It seems reasonable to assume, however, that the factors which affect separation in these segments are much the same as those which operate more dramatically in the reticulo-rumen in which more extensive mixing, greater volumes of ingesta and coarser ingesta are found. The contents of the abomasum consist of substantial quantities of liquid within which are suspended the finely comminuted food resi- dues (Schalk and Amadon, 1928). There appears to be little nifa-ze to ind 1:115 occurs Films, 195 Filipssn, 195 rattan my :05 331331ng at s 'r) L‘!‘"M“~ ‘ ous..g.“ ‘ Fl 3, u Lila heav 121133” in ratian occurs ~31.» « 1::1‘ .. . .‘vmt 1r ?. 'i ‘- .y. man; 1 I J 3:.“ ‘ '1'," "*3 or 3!. ml 4 ‘ r U \n~68t‘ ., «as l‘a‘. . 0‘ 0‘:- 27 evidence to indicate that differential passage of solids or liquids occurs from this organ (Phillipson, 1952; Masson and Phillipson, 1952; Dyce g3 §;., 1953; Began, 1957; Benzie and Phillipson, 1957). King and Moore (1957) point out that sep- aration may possibly occur in the intestinal tract due to the retarding of particles less dense than chyme in passing through ‘dm intestinal loops which lie in the position of an inverted HF, while heavy particles tend to pass slowly through intes- tinal loops in the ”U” position. Very little mixing or sep- aration occurs after the ingesta reaches the colon (Alvarex, 1940; Dukes, 1955). The Rate of Passage of Food Through the Alimentary Tract Under normal circumstances in mono—gastric animals and Iruminants no segment of the alimentary tract is ever empty, (and in every segment mixing of the contents occurs so that no Sharp line of distinction exists between the components of successive meals. The process of mixing is most effective in the first two compartments of the ruminant stomach and least significant in the small intestine. Foodstuffs pass rapidly through the small intestine of the ruminant in comparison to their rate of passage through the stomach or large gut. The anatomical arrangement of the large intestine in ruminants does not differ essentially from that of other animals; for this reason the delay in passage t‘r “dist!!! “ water that ""1’the sto' ,;Qt " 'f'= 133g. -. I.» finds 00 Q“ .n ‘ (Mia-4t was i 28 of foodstuffs through the alimentary tract of ruminants, which is greater than in other animals, must be due to the subdivi- sion of the stomach into four compartments and particularly to the largest compartment, the rumen. Methods of investigation Spallanzani (1784) was the first to study the passage of food materials through the digestive tract. He observed that feeds in perforated wooden or metal tubes required approxi- mately 25 hours to pass through the alimentary tract of the ox. This discovery was noteworthy in that this was the first evidence that passage through the alimentary tract of the ruminant was more prolonged than in other species. No par- ticular significance, however, was attached to this phenomena at the time. When experiments relating to the digestibility of foods were first entered upon in Gottingen in the 1850's, it soon became evident that it was necessary to know the rate of pas- sage of the food or the time of its retention in the alimentary tract with respect to the different animal species so that one might choOse the most applicable length of experimental period for the particular species involved. A large number of dif- ferent methods have been employed to this end. Early studies of the rate of passage were made by alter- nating the different kinds of food chosen in such a way as to 215:3” r9615 tins sate: : zeries, ccv'cer: 333:. 3! the 1 £9.53 gt 3! f. it 1;;ears to t "n) I 1! ‘u‘ ' my} 2“ ‘ndcra 3“.) that the tan ‘1':"Aq ' LA: 193’ *4 4 L W‘- 57:11 ‘9 adj "-!’l, 2 "£2. 1. 29 make their residues easily distinguishable in the feces. Various marker substances were also used such as sawdust, bil- berries, cowberries, pieces of cork, etc. (cited by Paloheimo, 1939). Of the various markers employed for studying the rate of passage of foodstuffs through the tract, the most widely used appears to be that introduced by Lenkeit and Habeck (1930) in which straw particles or grains are stained in such a way that the dye is retained as the material passes through the alimentary tract. They showed that the rate of passage of this marker through the alimentary tract of suckling ani- mals, after it was given in the milk, was much more rapid than if it was given with solid food which entered the rumen. The delay caused by the rumen was first investigated by Usuelli (1933) who demonstrated that fuchsin—stained oats left the rumen of the bovine in an exponential manner. Sim- ilar results were obtained for the camel (Falaschini and Angelucci, 1937). The same dye was also used by Columbus (1934, 1936) in his studies of the rate of passage of food through the rumen and the entire alimentary tract of sheep and goats. He added a certain number of pieces of-fuchsin-dyed straw, 2 mm. in length and 0.5 mm. thick, to the experimental food. By sampling the contents of the rumen with the aid of a stomach tube he was able to follow the reduction in the _ amount of marker in the rumen. Falaschini (1935) employed the stained-marker technique to show that the time required .‘:.'s 21m 1 :.‘ the sheep I: furt‘: 'I‘"‘ ‘1‘, a: «Moiiy’ 3123331. 'ne 0 Y “A 3. 1.93.1! I; 0‘ I‘ . I .5:.E:' y?‘l Q v.85: 0: :‘i‘J-a l 30 for a given quantity of feed to traverse the alimentary tract of the sheep was more prolonged than in the bovine. No further work on this subject, using the stained-marker technique, appears to have been done until Balch (1950) and Belch fiiuéle (1953) applied a method which was developed from that of Lenkeit and Habeck (1930) and Usuelli (1933) to in- vestigate the rate of passage of food through the alimentary tract of the cow. By employing several dyestuffs Belch was able to use several kinds of experimental foods at the same time. He also used cows with permanent rumen fistulas in his investigations. The procedure for studies of this type con- sisted of taking small samples of ingesta from a given part of the alimentary tract or from the feces and of counting the dyed particles found in the samples or of determining their aggregate weight. Castle (1956a, 1956b, 1956c), employing a technique which was based on the method develOped by Balch (1950), conducted similar investigations in goats. She showed that these ani- mals behaved in principle as cows, though they were more vari- able. Biondo (1953) measured the time of first and last appearance of stained cats in the feces of five kids and five adult goats; he found that food passed through the alimentary tract of young ruminants slightly more rapidly than in adults. Blaxter 33 gl. (1956) studied in detail the fecal passage curves derived from feeding stained, dried grass to sheep in tempt to alt {urination 0: 2212'. Lth tit zit-ts i=“""°t :eiizticn of t: testi‘dlity c: 13322:! excret invhd 5.. (2:31.31 "He d 2.1m miel t n» i ' as. nick 1 )“t vent?! trac‘ 31 an attempt to elucidate some of the problems involved in the determination of digestibility coefficients. Using a kinetic system with two successive rate constants as a model these authors mathematically derived equations which allowed the prediction of the errors of digestibility coefficients, the digestibility coefficients themselves and the diurnal pattern of feces excretion. More recently Brandt and Thacker (1958) subjected the data of Balch (1950) to mathematical treatment, using a model based on hydraulic flow through two volumes in each of which complete and instantaneous mixing occurs, and derived an expression similar to that obtained by Blaxter g3 g1. (1956). Inert plastic particles, ranging in density from 0.92 to 1.24 g./cc. and in size from 11.5 to 188.0 cc./1000, were used by King and Moore (1957) to evaluate the effect of par- ticle size and density on rate of passage through the ali- mentary tract of steers. The particles were recovered from the feces by flotation and separated into size and density classes with the aid of white or ultraviolet light. Plans (1953), applying an original technique for resec- tion of the rumen of the sheep, observed that the disappear- ance of a single stained meal from the feces was much slower before rumenectomy than afterwards. Complete removal of such an important organ, however, might well alter the whole pat- tern of the digestive processes in other parts of the tract. he Me 0 Iv I 53-3135 in k "I W”. o.” .O_‘Led E $231 gift”! unnuv ' H. a l “Gnu Uru‘ "er ‘ . Q 'I .l‘l 513‘ to st“:- ‘2 I K}:e“ ‘ , .t‘gn‘e V‘ ' 3.. . “I a. ‘9 x "1 ls»- ‘ i "b:0fl\ ‘4 EVA ..E _ Q“ l“s ‘T. 32 The use of inert reference substances, although widely employed in the determination of digestibility, has received more limited application in studying rate of passage. This method differs from the stained-marker technique in that the reference substance can be determined quantitatively. Sperber gt g1, (1955) used water-soluble polyethylene glycol to study passage of ingesta from the reticulo-rumen. These workers estimated an outflow of 150 to 170 liters per 24 hours through the reticulo-omasal orifice of a 530 kg. cow. This substance was subsequently employed by Hyden (1955) to study its passage through the alimentary tract of both cows and sheep. Ferric oxide, introduced as a reference substance for determining digestibility by Bergeim (1926) and later used for passage studies in ruminants by Mitchell gt a1. (1928), Moore and Winter (1934) and Rathnow (1958), was found to be unreli- able by Hale gt g1. (1939, 1940) who observed that the passage of ferric oxide appeared to precede the passage of ingested material from the rumen. Edin (1926) employed Gr203 as a reference substance to investigate the rate of passage of food through the alimentary tract of a number of farm animals. Paloheimo (1939) used the Cr203 method to study the rate of passage of small concentrate rations through the reticulo-rumen of cows. Poijarv1 (1952) similarly applied the Cr205 method to his investigations of :5 . :33)” it! :yanin 6:115: in ('3 1:: d fell 2:11:55 even 133.91 ever t .32. ice 1: statute in iizeers bn‘ u‘:" Huh] ‘1‘- . 'J ‘3‘ t 'e “c ‘ ‘1 .a“5 ‘E I Won ( v~iPEIn ~ W472: ‘:~i \- M: 35 the relative rate of passage of small and large rations through the alimentary tract of wethers. Mere recently Lam- bourne (1957) has shown that Cr203 or Monastral Blue (capper phthalccyanine) given with stained hay to sheep appeared earlier in the feces, reached an earlier peak of concentrap tion and fell slightly faster in concentration than the hay residues even though both types of marker substances were ex- creted over the same general time interval after administra- tion. The initial more rapid passage of Cr203 observed by Lambourne in sheep was substantiated by Belch gt a;. (1957) in steers but the data of these latter authors suggest that once Cr203 has become well mixed with the ingesta its rate of passage from the reticulo-rumen is probably not markedly dif- ferent from that of dry matter. These recent findings re- emphasize the limitations of the use of reference substances in studying rate of passage in that any marker will be indica— tive of the rate of passage of the particular fraction of the food with which the marker is associated or of the marker it- self if free in the medium. Thus, comparisons between the ratio of the marker and a constituent of the ingesta which is traveling at a different rate through the rumen or gut can Ilead to fallacious results. Cannon (1898) appears to have been the earliest to apply roentgenology to study the passage of food through the ali— mentary tract. He used bismuth nitrate mixed with the experi- 27mm“. 'I n‘.“‘b9\ 21:: a! the It": has ;n £11111} it a '_ -) O .p. l‘ . v22 at 2:3: MI' “.395: {3: this or . ’3! tract, (.1? .1 E a a. e ~‘h. ‘ i WW I ,It 1'! ‘~'ee‘.\‘{ 1M8] \I‘ I h" Ex‘a‘ “u . \ .‘.;r§ 34 umntal food as a contrast substance. Later barium sulphate was employed for preparation of the contrast mixture. Czepa and Stigler (1929), Magee (1932), Trautmann and Schmitt (1935) and Phillipson (1939) studied roentgenographically the move- ments of the stomachs of small ruminants. Although this tech- nique has proved valuable in studying gastro-intestinal motility it has been the general opinion until recently that such a method is not suitable for studying the rate of pas- sage of food through the stomach of ruminants since the pulpy contrast food tends to remain in the reticulo-rumen for periods of abnormal length. Studies of the ruminant alimen- tary tract, presented and illustrated in an excellent mono- graph by Benzie and Phillipson (1957), indicate, however, that valuable results with respect to rate of passage can be ob- tained by cine-radiography providing the proper equipment and techniques are employed. Grouven (1865) calculated the time required for the digestion of a designated food ration from the formula B = I 4 200 T/200 A-ac days, where B s time required for diges- tion, T a dry matter contents of the alimentary tract, A a dry matter content of the daily food ration, and C = per- centage of digestibility. Slaughter experiments are thus the .prerequieite for the application of this formula. In slaugh- ter experiments with rams Wildt (1979) used the silicic acid content of the ingesta in the reticulo-rumen and of the feed u; . ”.‘r ‘ ‘ .5‘1‘ste 722:. it! I as result it ~ I Jl'.‘ '°‘.cu u o.U 13‘: fl ' ‘ am the “g. Q s: :V‘e ““1 311'. High M, ‘ ul ‘5 '5‘“ a “C b M“ ‘ c L... “K, 55 to determine the time of retention of the feed in the reticulo- rumen. His method of computing rate of passage gives the same result which is obtained if the amount of silicic acid in the reticulo-rumen is divided by the amount or silicic acid in the daily ration, the time of retention being expressed in days. The necessary assumption in this computation is that the mean time of retention of silicic acid in the reticulo— rumen is, for all practical purposes, identical to the mean time of retention of dry matter in the reticulo-rumen. If the silicic acid is uniformly distributed in all food particles then this method will give an accurate idea of the rate of passage of dry matter; there appears to be no experimental evidence, however, to indicate that such an assumption is f applicable. Ewing and Smith (1917), in an attempt to determine the rate of passage of food residues through the alimentary tract from the water content of the feces, were able to show that some relationship did exist between a high-moisture feces and a high rate of passage but were unable to obtain any abso- lute values by this method. By using slaughter tests these authors succeeded in computing with a comparative degree of accuracy the average time required for the residue of a cer- tain meal to pass through the alimentary tract of_the steer. The mean time of retention of the indigestible food residue in the alimentary tract was calculated from the formula I , . we . flames ‘3': ‘ u mite, C 32:, R the dry \ .nhéth j '1 : 'v he were “i. .k. a m (.3:- gVepc 2; h: agrees Vi‘ 38fthe (€369 353: see: to 1'23 {0,338 n t car. b I'I “ \ "it“. .. e K“ 353'? q 2» . 36 r e C "§*I‘F_ 2 where T denotes the mean time required for the passage of the food residue, C the dry matter content in the alimentary tract, R the dry matter content of the food eaten per unit time and F the dry matter content of the feces voided per unit time. The prerequisite for the accuracy of this formula is that the average composition of the contents of the alimentary tract agrees with the weighed average composition of the food and of the feces, a fact which has not been shown experimen- tally to be true. The investigations of Paloheimo and Mahala (1952) seem to indicate that the requirements for the validity of the formula are not fully satisfied. The formula of Ewing and Smith can be derived from Grouven's formula if the addi- tive term I is omitted. Consequently, Grouven's formula yields values exceeding those obtained by Ewing and Smith‘s formula by I.‘ The objective of Ewing and Smith was to obtain the mean time of retention of the food residue in the alimen- tary tract, whereas Grouven attempted to arrive at an eXpres- sion for the time from the intake of the food to the excretion of its last residue in the feces. Paloheimo and Makela (1952) and Makela (1956) applied the lignin-ratio technique to calcu- late the mean retention time of food in the rumen, or in the entire alimentary tract as the case might be. Particular attention was paid to the retention of food in the reticulo- m: if the c iltssei on tt 3:11;". necess 1. hair 31“.! retici "3.3:: even I “by. .s ‘ ‘l “'91“! I'- , ‘ V K "63"! 57 rumen of the cow. The method of computing time of retention is based on three prOpositions, the validity of which is a logical necessity. 1. During uniform feeding the amount of dry matter leav- ing the reticulo-rumen in 24 hours equals the amount of dry matter entering the reticulo-rumen within 24 hours. 2. During uniform feeding the amount of contents in the reticulo—rumen assumes a constant value. 3. If after uniform feeding the dry matter contents of the reticulo-rumen amount to n times the daily dry matter in— put, then the mean time of retention of dry matter in the reticulo-rumen equals n days. All of the dry matter is taken into account, independent of whether it leaves the rumen by way of the reticulo-omasal orifice, through the walls of the rumen or in the form of gases. In accordance with the prepo- sitions presented above, the average time of retention of dry matter in the reticulo-rumen, in days, is computed by dividing the dry matter contents of the reticulo-rumen by the daily intake of dry matter. Although methods used for computing the mean time of retention give figures which are useful for comparing the results of different experiments, the tech- niques are not generally applicable because of the need for slaughter. Methods employing various fistula techniques have been used for measuring the passage of ingesta at different levels ' H 9“ u 'l ”E 5...:98155. w 1 a1. (1 L—‘il at": a! steers I NW" P‘r. “Jams hf crv "re-"MI figs ‘ .A .. I...“ b.\,.. ‘-' n a o ' p ‘1’} p H “a saint?. . . :r lav .pw‘.~l "39%" "W'slt- ‘ ~ ("in .9 .- ~‘0n y‘ Lze L \t: :‘“D':‘ ‘1- ' ‘:.~~~. L. 38 of the alimentary tract. Hale gt g1. (1947a, 1947b) and Chance 91; gl. (1955a) studied the passage of ingesta from the rumen of steers by removing, sampling and replacing the rumen contents before feeding, six and 1? hours after feeding. The assumption was made that all of the rumen ingesta which could not be accounted for had passed from the rumen either by ab- sorption through the rumen wall or by passage into the re- mainder of the alimentary tract. Sampling-~time complica- tions appear to be major limiting factors in the applicabil- ity of the method. Bouckaert and Oyaert (1954) have described a method for measuring the passage of ingesta from the omasum of sheep but no detailed account of the results obtained by this procedure is yet available. The passage of ingesta from the abomasum of sheep has been investigated by Phillipson (1952) who employed duodenal cannulation to collect and measure the ingesta. Collections over long periods and estimates based on the weight of washed plant residues in the duodenal ingesta were used to assess the total passage. Expressions of rate of passage The rate of passage of food in the alimentary tract has been expressed in a number of various ways. (It frequently is given as the time from ingestion of the food and its first appearance in the feces or as the time from ingestion of the Trial-i it! 1 5:31: a: inf sighted Ioc Elmer ex; 3121: since ”Iv-3M“. 'f-Voe . 3 metre “fried of . L751} ‘1 V" 1- "w. :0. 4, a ”3368: A”TI-"‘3 a: (o “" “ltd“ ' 2M (.3 e 'i‘.‘ x“ 59 food and its last appearance in the feces. The first expres- sion is an indication of the maximum velocity with which an undigested food residue passes through the alimentary tract. The latter expression has to be considered indistinct and un- reliable since observation of the last undigested residues of a specific meal is strongly dependent upon the accuracy of the procedure and since a certain amount of the undigested residue tends to remain in the alimentary tract for a prolong- ed period of time. Both of these eXpressions have been em- ployed by Mangold (1950) and Biondo (1955) whereas only the latter expression was used by Grouven (1865). A more accurate estimate of the rate of passage of food and food residues through the alimentary tract or through any of its parts can be obtained by stating, in addition to the first and last appearance of residues in the feces, the time at which maximum excretion occurs. This procedure was adopted by Usuelli (1955), Columbus (1954, 1956) and Lenkeit (1955) who, in addition, presented curves in which the progress of excretion could be followed for several consecutive days. Presentation by means of tables or-of corresponding excretion curves showing the continuous cumulative percentage of the total undigested residues produced at any time after feeding has also been used by Edin (1926), Moore and Winter (1954), Belch (1950), Poijarvi (1952), Castle (1956a, 1956b, 1956c), Blaxter gt gt. (1956) and Lambourne (1957). When the results es erreseed E‘ :ezvee: expert: N "were 1‘“). :15, 50 iii 50 agate teaser mm. In or: leg-2c Castle ( F'Ihich was 6 35119curves. 71!?5 of excre: men: then 1 he was take: {13533, or T he UPOC a 40 are expressed merely as excretion curves precise comparisons between eXperiments are difficult. Although it is possible to compare individual points on the curves, such as the times of 5, 50 and 80 percent excretion, no single points give an adequate measure of the shape of the curve over its entire course. In order to compare the curves along their entire length Castle (1956a, 1956b, 1956c) introduced a value termed 'R' which was directly proportional to the area to the left of the curves. ('H' was calculated by adding together the times of excretion from 5 to 95 percent at intervals of 10 percent taken from the graph and dividing the sum by 10. This value was taken as a measure of the mean time of retention, in hours, of residues in the alimentary tract. The procedure used by Ewing and Smith (1917) to calcu- late the average retention time of undigested food residues in the alimentary tract has been previously mentioned. They expressed the time of retention in terms of one characteristic value only. This also applies to the means of expression em- ployed by Grouven (1856) and Wildt (1879). Paloheimo and Makela (1952) and Makela (1956) introduced the term average time of retention of a dry matter point. This is understood to represent the average time required for the dry matter points to stay in the alimentary tract as a whole, or in its constituent parts. When expressed in terms of a lignin point, this concept is comparable to Blaxter gt gt. (1956) mean-time (it: was defined sized articles :32: of particle 3:: it and T tee-3129 could t hie earns; :a a single (7 5' 1‘: aeration on finite were of u". ' " "")V‘nr§ "' 44..- (.81 ‘) . ““3 on (.3 113$: , -.. L” if?“ M as 00113 35». 41 which was defined as the sum of the times that individual stained particles spent in the tract divided by the total number of particles. Brandt and Thadker (1958) felt that, even though the mean—time could be calculated from the parameters of Blaxter's kinetic equation, this concept was not an easy one to use and that a single value did not adequately describe the shape of the excretion curve. These authors presented data calculated from the work of Balch (1950) to support the premise that in the ruminant a two volume model describes the observed data. Rate of passage was expressed as two half times which pre- sumptively referred to the reticulo-rumen and to the omasum, abomasum and intestines, respectively. Rate of passage —tactors influencing rate of passage Data on the rate of passage of food residues through the alimentary tract have, for the most part, been presented either as concentration curves or as excretion curves. This factor, together with the widely different techniques employ- ed, makes it difficult to compare results. Insofar as pos- sible, however, comparison have been made between the various investigations with regard to the time required for the ini; tial excretion, maximum excretion and final excretion of the reference residues in the feces. These results are summarized in the following table. Rate 0. Name N‘ u NH Lela-i) (1933) ‘ ‘ I 12:14! :1 “ (a ., , A 1:0-8 “ Lia ."'A ‘ . _ t” ( r find. “8 ‘1‘: 42 Rate of passage through the alimentary tract of ruminants. Initial Maximum Final Reference excre— excre- excre- Reference Animal food tion tion tion hr. hr. days Lenkeit (1955) Sheep Date 12-15 48 14-21 Cow Oats 8-12 48-72 14-21 Usuelli (1955) Cow Oats 7-9 72 11 Columbus (1954) Goat Straw 12-15 48 15-20 Falaschini (1955) Sheep Cats 22-28 48 14 Balch (1950) Cow Hay 12-24 70-90 7-10 Biondo (1955) Goat Oats 12-15 -- 11-17 Castle (1956a) Goat Hay ll-15 20-50 6-7 Lambourne (1957) Sheep Hay 15-20 50-48 6-7 The characteristically sigmoid-shaped excretion curves ob- tained by Balch (1950) in his studies on the rate of passage of food residues through the alimentary tract of cows receiv- ing hay as the basal food appear to be typical of adult cattle. The initial residual particles of stained hay appeared in the feces 12-24 hours after feeding and excretion of the first 10 percent frequently required an additional 10- 15 hours. The next 70 percent were excreted more rapidly at approximately 1.5 percent per hour, the excretion of 80 per- cent requiring 70-90 hours from ingestion of the meal. After the curves 2‘ 2:12:13 decrees: 4111910! (he 1 as: he rem main tite'. 33135.3( 5 per ’0. ‘5‘ . “Nuns End a: fist! ' 9‘s "‘ ‘ Vue e. is" us rem ) m ... 4).: H‘s; at. CC‘ V )- ~-.. 9 ' I the “a '4 l_’::. \ $‘P “-9 43...; q... I A“ 3., ,1! “is (‘4- Id 43 this the curves rapidly flattened and excretion continued at a slowly decreasing rate until 7-10 days after the meal. As an index of the time required for passage of a reference meal through the reticulo-rumen Balch introduced the ”80-5 percent excretion time". This was the time interval between the ex- cretion of 5 percent and 80 percent of the food residues in the feces and appeared to be the major determinant in the spread of the excretion curves. The "5 percent excretion time” was remarkably constant and was indicative of the rate of passage through the omasum, abomasum, and intestines. Castle (1956a, 1956c) obtained results with goats sim- ilar to, but more variable than, those obtained by Balch (1950) with cows. The time required for excretion of 95 per- cent of the reference hay from goats receiving a basal ration of meadow hay and "calf nuts" ranged from 60 to 87 hours. Ewing and Smith (1917) and Ewing and Wright (1918) cal— culated that the mean time of retention of food residues in the alimentary tract of steers receiving a moderate ration of silage and concentrates was 72-84 hours. Comparable re- sults were obtained by Paloheimo and Makela (1952) and Makela (1956) with cows which received hay as the only food. Wildt (1879) computed the average time of retention of barley straw in the reticulo-rumen of the ram to be 21.8 hours when the daily intake was equivalent to the gg libitum amount. Columbus (1954, 1956) observed, after feeding stained straw :: sheep and go mmhhtm humemi :rfianor the hmgnms :rtre of the finance tubs ‘3. men with an? ehv ‘ tings“ 44 to sheep and goats, that the marked meal was uniformly dis- tributed in the rumen after 1-2 hours and that passage into the omasum and abomasum had begun in 2-5 hours. The major portion of the meal had passed from the rumen in 24 hours. Investigations by Lambourne (1957) indicate that 50 percent or more of the hay or pasture forage as well as the inert reference substances fed to cattle and sheep had passed from the rumen within 24 hours. Castle (1956a) found that the mean time of retention of hay in the rumen of goats was 52-44 hours with passage from the rumen occurring at about 2.1 per- cent per hour. This rate was comparable but somewhat more rapid than the passage of 1.5 percent per hour observed by Balch (1950) in cows. As far as can be determined from the concentration curves given by Usuelli (1955) and the excretion curves presented by Balch (1950) for stained residues in the rumen of cattle approximately 50 percent of a meal of hay disappeared from the rumen in 24 hours, and about 80 percent in 48 hours. Ewing and Wright (1918) found that the average mean time of retention of food residues in the different parts of the alimentary tract of steers which had received either silage or cottonseed meal, or both, was 61, 7.9, 2.8, 6.7 and 7.6 hours for the rumen, omasum, abomasum, small intestine and large intestine, respectively. Values computed for a steer receiving 2.65 kg. of dry matter from silage were as follows: 32:65 heirs, intaoO‘e. ‘ C h u.. ... there: the a With con i?! utteri It: ”'15 TESiiue C! 31"» har‘ 4 i21ps:n (19 L‘J'ieautrlo' ‘5: '1" :N‘ 5‘. “" Jfl‘wt ' C r“ r! ‘H. 5“ 4 ten‘ hf. . ' § ‘4. ‘n'eseq "AI 45 rumen 65 hours, omasum 11.4 hours, abomasum 2.1 hours, small intestine 5.2 hours, large intestine 7.5 hours. Similar re- sults for the mean times of retention were obtained by Makela (1956) with cows which were fed hay at comparable levels of dry matter intake. These results indicate that the passage of food residues through the omasum is relatively slow. 0n the other hand passage through the abomasum is rapid. Phillipson (1952) used duodenal canulation of sheep to meas- ure the outflow of ingesta from the abomasum and observed that flow from the abomasum was continuous. Czepa and Stigler (1929) found in their X-ray studies of sheep and goats that contrast gruel introduced into the abomasum was emptied into the intestine within 4-6 hours. The retention of food residues in the intestine appears to be insignificant in comparison with the retention in the entire alimentary tract. This is particularly true in the small intestine (Makela, 1956; Benzie and Phillipson, 1957). According to Mangold (1950) the rate of passage through the intestinal tract is dependent upon the length of the tract and in general tends to decrease with decreasing intestinal length. ’ The ratios between the mean times of retention in the reticulo-rumen, in the alimentary tract caudad to the reticulo- rumen and in the entire alimentary tract are summarized in the following table. It can be seen that the ratio between the 1 :10 be‘. resiiues :J _. m“ ..:e 46 Ratio between the mean times of retention of feed residues in various parts of the alimentary tract. Ratio Meaggretention Rumen Lower Tdtal Reticulo- Lower to gut to Reference Animal tract rumen gut total total hr. hr. hr. Ewing and Wright (1918) steer 86 61 25 0.71 0.29 Balch (1950) cow 80 56 24 0.70 0.50 Makela (1956) cow 87 61 26 0.70 0.50 Castle (1956a) goat . 54 58 16 0.70 0.50 Lambourne (1957) sheep 74 52 22 0.70 0.50 mean times of retention in the reticulo-rumen and in the en- tire alimentary tract is fairly constant. This ratio is approximately 0.70 and its value appears to be independent of the dry matter intake or of the nature of the ration. The mean time of retention in the alimentary tract caudad to the reticulo-rumen is approximately 50 percent of its time of retention in the entire alimentary canal. It is interesting to note that these ratios are, in all respects, similar to the ratios between the relative capacities of the same re- spective segments of the alimentary tract reported in the literature (Sisson and Grossman, 1955; Dukes, 1955). Evidence presented by Makela (1956) lends further support to this ’ point. The distribution of the contents of the alimentary 5:: between it: 21551138 7.1 3e Ste 'f-te 0‘ ;s stilett to c MA ‘ 4 m mitt 3‘7. It a in PE. 'icClE ‘r é'a a "was it b has». r. tre I * 3° Siov' 'c.': . 99 in “ Q In“ ‘cl‘3: 10K V‘s ‘b ‘ “4 ‘ we ’8 | '4- D: e I" ‘- .'s‘ 3,9». . \‘E. ., ._e “a! u l ‘- \= . v .‘:§ 4&6! ‘ . -E:‘; “ I a“; i 4 as :U .: 4‘ at a. 47 tract between its different parts in cows which received at least 9 kg. of hay per day was as follows: reticulo-rumen 71.4 percent, omasum 9.9 percent, abomasum 2.4 percent, small intestine 7.1 percent and large intestine 9.2 percent. The rate of passage of food through the alimentary tract is subject to considerable variations, depending on the quan- tity and quality of the food ingested. The level of intake is of particularly noticeable influence and yet this factor has frequently been overlooked in presenting data pertaining to the rate of passage or time of retention. In fasting ruminants it has often been observed that passage through the alimentary tract proceeds very slowly after initiation of the fast; so slowly in fact that it seems lOgical to assume a decrease in rate of passage. Grouven (cited by Ritzman and Benedict, 1938) fed two oxen and two cows with a ration of 7.7 pounds each of rye straw daily for a period of two weeks. The cows were slaughtered immediately after feeding and the oxen after 5 and 8 days fast, respectively. The contents of their alimentary tracts were weighed and the observation was made that the quantity of ingesta in the alimentary tract of the fasted oxen was only slightly less than that of the cows. Although the comparative size of the animals and the increase of the water content in the alimentary tract as a result of fasting was not without significance, it appears plausible to -assume that the rate of passage of dry matter through the beam! trac 51:12: resul s 561nm ‘ its: the Me $1295 in 3 ca 531m in, h 0 ~ ’43.??? $36 48 alimentary tract has decreased as a consequence of fasting. Similar results were obtained by Nevens (1928). Columbus (1934) observed that a 24—hour fast before and after the reference meal, which included 100 g. of oats, re- sulted in a cessation of passage from the rumen of sheep on the first day. Resumption of feeding resulted in normal pas- sage from the rumen. A fast of longer duration had a like effect but was more pronounced. Fasting also resulted in pro- longed retention of food residues in the entire alimentary tract, thus increasing the time interval between ingestion and maximum excretion. Columbus (1934) fed a basal ration of hay at two levels of intake, 250 and 1000-1200 g., to sheep; each ration was supplemented with 350 g. of ground oats mixed with stained rye straw. Two thirds of the reference straw had passed from the reticulo-rumen after 24 hours when lOOO~12000 g. of hay per day were given to each animal, whereas less than 50 per- cent of the marker had escaped from the reticulo-rumen in 24 hours when only 250 g. of hay were given daily. Emptying of the rumen was further delayed when all of the hay was with- drawn from the ration. Data presented by Makela (1955) for cows receiving hay indicate that the time of retention of dry matter in the reticulo-rumen is dependent to a large extent upon the level of dry matter intake. The correlation between the mean time of retention of dry matter and the level of dry ! . 9129: 151216 h 1:“: 'COx + ( A. I 352335.3(1 C09 "00;, 2 .‘Io 4Hvl . any tr m huv u be.\ QQUFAQ ' "‘- .Jfll‘: c I :‘A‘ ‘N‘ v‘ ‘ \v“< r.‘ i ‘U on K‘. "& ‘\“,fln -\ t. _5‘. 49 matter intake was -0.74 1 0.09, the regression coefficient being -0.56 t 0.10. Makela concluded from the value of the regression coefficient that the mean time of retention of dry matter in the reticulo-rumen increases by approximately 12 hours when the dry matter intake decreases by one pound per 100 pounds of reduced net weight. Additional evidence that the rate of passage for a given ration increases as the level of intake increases has been obtained by Ewing and Smith (1917) with silage-fed steers, by Blaxter gt El- (1956) with dried grass-fed sheep, by Castle (1956a) with hay-fed goats and by Lambourne (1957) with pasture-grazed sheep. On the other hand Balch (1950) found that in cows with a high level of dry matter intake, consisting only of hay, the passage of hay from the reticulo-rumen was more prolonged than in cows with a lower intake. This result is in direct contrast to those of the preceding investigations. PoiJarvi (1952) investigated the effect of both quantity and quality on the mean time of retention of food residues in the alimentary tract of wethers. The following rations were fed: 500 g. hay, 1000 g. hay, 500 g. hay + 200 g. bran, 600 g. hay + 400 g. bran. The results obtained indicate that the mean time of retention of the food residues was about 2 days when the level of intake of hay or of the same total quantity of hay and bran was high, whereas the time of reten- tion was 2 1/2 - 3 days when only 500 g. hay or the same total 31:31 of 2:212 was t ‘:.&'.IAI I“ "Mute-ll. .1. ;;'.“!v§ { “Jim... 8 \ l".. VVHV'. ‘! k? ~ H nu?) ‘| ”SIP ‘w ail: ‘hn‘ Q‘.‘ in “a flu,‘. ‘a"\\,‘ 5 lie,” .J ‘:‘?§ . V e! ‘ C t ‘L h. '15 n“ "J L‘ 50 quantity of hay and bran was given. An increased level of intake was thus clearly associated with an increased rate of passage. Considerable attention has been paid to the quality or physical makeup of the ration, particularly in regard to the retention of concentrates or finely ground roughages in the different stomach compartments of the ruminant. According to Amadon (1926) and Schalk and Amadon (1928) ground cereals and other concentrates, being heavy, may enter the reticulum soon after ingestion and may even reach the omasum and abomasum at this stage. Bulky food, on the other hand, finds its way into the posterior part of the rumen. The rate of passage of concentrates or finely ground roughages might thus be con- siderably more rapid than that of bulky food. Mitchell gt 5;. (1928) were also of the opinion that heavy food, such as grain, will by-pass the rumen and pass through the alimentary tract in a relatively short time, particularly when fed at high levels of intake. The results obtained by King and Moore (1957) do not appear to support this point of conten- tion. Inert plastic particles ranging in size from 1/8 inch to 5/8 inch on a side and in density from 0.92 to 1.24 g./cm.3 were employed to eliminate confounding of the data by pro- gressive changes in particle size, density and composition. It was noted that maximum passage rate occurred with particles which had a density of 1.2 g./cm.3 and a size of 20 to 50 x I" 33.5. I o - "1 'rl LIE- L's-s ex”! Fl; (New: Y“ 1.. .. ‘K‘M to I‘.¢‘ 64 ~le-er ‘99: w L I." I - \ 3...? 212:6] 1:“; =3 5:216 w; a, Q“ 1 A. ‘ ' A ' . "#854 ”a :.,~ ~., 4 591 :7“ ,‘h. , '.'T“_‘ a“. w" ‘ ~ ‘ T 1.3-: " ~I ,. I.. \‘n. v” ‘n "‘e ‘1 h! 1;: o r“: v “31“, A, l .2’ g Q -: no “a 51 10’3 cm.5. Particles either much lighter or much heavier than this exhibited a slower rate of passage. Heavy particles were found only in the bottom ingesta; almost all of the lighter particles had been regurgitated and chewed. Balch and Kelly (1950) have established, however, that cows which were fed an ample all-hay diet did not diaplay any marked differ- ence in specific gravity of the particles of ingesta between the dorsal and ventral sacs of the rumen. A further incon- sistency as to the effect of density and particle size arises when heavy inert indicator substances such as Cr203 are con- sidered. 0n the basis of the movement of the plastic par- ticles of King and Moore (1957) Cr203 would be expected to move very slowly through the alimentary tract. Since Lam- bourne (1957) and Balch g£,g;. (1957) have shown this is not the case, factors other than density and particle size must be dominant in determining the passage rate of heavy indi- cators. Some investigations tend to indicate that the rate of passage of concentrates is not as short as was previously be- lieved. Concentrates enter the rumen after ingestion and are thoroughly mixed with the rumenal ingesta previously present within a few hours (Nevens, 1928). Paloheimo (1939) deter- mined the time of retention of a small concentrate ration in the reticulo-rumen and omasum of cows. The cows were fed 2.2 pounds of concentrate in addition to hay. Forty eight hours J F ii". reli‘...€ :- 315511:- . ‘ ‘ lady? 5.8. uni-'0‘»- .0‘ 3'". "‘r\ n "H-i.- A y . . ‘ . ' ’ P a ni so! sin. c d ‘3'. "2 I ~I “’y, &“ up .I I I: ‘V'us heel w" _ V f ‘0 i 4 “. I‘vsJ ..S a h.“"~‘n .n ..' !' \w‘ J. f: r l' ‘ I ‘ .t‘ 1 S“, “V ‘. u in: ‘\ I.“ 9'2‘ ‘. ‘ 0‘ -‘ h ”:97- . "y . V 5’ in; ”'0! h.‘ ‘ x “I -.‘ “ 3M... . :‘u ‘ C 3%.: I‘k‘ “A, ‘ r‘:‘ 5', ‘ 'oauv‘ A‘I 52 were required for 90 percent of the test meal to pass beyond the omasum. Usuelli (1933) obtained somewhat similar results feeding stained oats to cattle. Balch 22 El- (1954) fed vari- ous hay to concentrate ratios to cows. It was noted that the excretion curves for hay became extremely prolonged with diets low in hay. The slow passage of the rations containing little hay may, in part, be eXplained by the reduction in total quan— tity given. In view of the marked effect of level of intake on passage, it is possible that any differences discernable were more apparent than real since the cows in these investi— gations were given part of their ration in prOportion to their milk yield. As a general rule, finely ground food passes more rapidly through the alimentary tract than similar food, or the same kind of food, more coarsely ground. Lenkeit (1933) observed that ground oats remained in the alimentary tract of sheep for a shorter period of time than whole oats. Columbus (1934) found that finely ground barley spent less time in the rumen of sheep than coarsely ground oats when hay was fed as basal food. The results of Balch (1950) indicatethat the residues of ground hay were excreted from the alimentary tract of the cow considerably faster than those of long hay.when long hay was used as the basal food. Blaxter gt g1. (1956) fed dried grass prepared in three different ways to sheep: finely ground and cubed dried grass; medium ground and cubed dried ‘ 6' . :f :e was n. is :ztunt give ‘t"“ Sr. 2“ |l|kls Ohfia...l tv..=" u . 7‘.- vb- fiE “lit; 132:? e iiff . ‘. “Ty v‘ ‘ -; jkerifi. 3“. .Q . '! \g31q 'HH 4 £ ‘ Q "I . .\:_‘. ‘ ‘-'. | PH; “‘ = ‘ p“ U“ A . v \‘rzf‘ A 53 grass; long dried grass. Their results indicate that passage of the grass through the alimentary tract increased both with the amount given and with increased comminution. The fact that finely ground, cubed grass passed through the alimentary tract of sheep more quickly than long material is contrary to results obtained by Balch (1950), who used ground hay in ex- periments with cows. Whether this reflects a species differ- ence or a difference between cubes and meal is not apparent. It is of interest, however, that all of Balch's cows given ground hay excreted it much faster initially than long hay, and in one instance this initial rapid excretion persisted up to the time when 90 percent of the meal had been excreted. The differential passage of small particles compared to large particles has interesting implications. It suggests that finely ground feeds leave the rumen more rapidly than long material and that the act of rumination by grinding large particles into small particles speeds the passage of food from the rumen. Gordon (1958a, 1958b, 1958c) studied rumination in detail in sheep and found that it was difficult to disturb the normal pattern of distribution of ruminating periods throughout the 24 hours. The total time spent in rumination was surprisingly constant irreSpective of diet, the one exception being the well known response to grinding -the food to a fine consistency, a procedure which markedly reduces the time devoted to rumination. Even a change in the t I. ‘F ‘ :- JLJLE " ..’;”‘.fl‘ ' I‘ U u .boou.‘ .J a... v! ‘ k .:. I b I \- ‘. C. “ . \: ‘; wu‘“ \ a‘. ‘a - P\ ‘\i I .‘w‘ \o-“- --‘ w. a ~\. ‘ o \n b \ 54 times of feeding caused little variation. Gordon concluded that rumination is an inborn instinct of the sheep and bears no obvious relationship to the food the animal eats under normal conditions. He further found that the rate of passage of stained residues to the abomasum was greater during periods of rumination than during resting periods as far as could be Judged by the concentrations appearing in that organ. Phil- lipson (1952a) found the outflow of ingesta from the abomasum of sheep to be continuous, although short periods occurred in which no flow was observed. These were commonly found on feeding hay but not with meals for with the latter the flow rate increased. Rumination resulted in a more regular flow of ingesta from the abomasum. Green forage remains for a shorter time in the alimentary tract than corresponding dry roughage. Columbus (1934) found that an 8.8 - 11.0 pound ration of green forage passed more rapidly through the rumen than a 2.2 - 2.6 pound ration of hay. He attributed this to the greater intake of food and to its higher water content. Balch (1950) observed in experi- ments with cows that the dry matter content of the total in— take (food and water consumed) has considerable influence upon the time required for passage through the omasum, abomasum and intestines. As the dry matter content of the total intake increased the time of retention also increased. These results are in good agreement with those obtained by Castle (1956a, .n.‘) ("I ‘ -" .t. u ,..'v4 :c‘ ‘r at 512235 were u. ‘ ‘ -I 19;. 3. t1 ”.9“ ‘3‘) h. ""Ich 'v-.v ['2'13 “IA“ ”hm" ligand C 9|:s pin. I‘ h“. d". u | m an" ‘ 'oat... V ,n- “3" OT! ' "‘I m. 1" :0 “ate ‘ v..5 u‘ ' a ig'l Q~Q.Q‘ 9 ‘~_“ H: , I“: I'dSnO; a. - y. . ’ct'.‘ : “In . It a. .' ::§~ inn,- . 1.. R “s G. :‘ ‘rk‘. I '1 ' v-O "N .- n “ i9“: . g‘ ‘ .I ‘ "a ‘2 ‘1 ‘i ‘vw \ M :u §.. 2“ 2 h‘ “I I. K‘- "(:. ‘1‘ ‘ Q .‘ ‘3: “"'v “\- ‘.' .:“ ‘ “HG! ‘« .:'!:_. .‘:e 1'- ta ‘\ n a: ‘- ‘uQP: \ ‘I‘u "‘- :\ . "e “a: k,‘ in 55 19560) with goats. Balch gt gt. (1953) conducted an investigation in which six cows were given, during the time of the eXperiment, 60 percent of the quantity of water they had consumed during the control period. The cows were fed 18.0 pounds of alfalfa hay daily. The restriction of water intake had no noticeable in- fluence upon the rate of passage of food from the reticulo- rumen nor on that of the food residues in the entire alimen- tary tract. Many experimenters have sought a relationship between the rate of passage of food and digestibility. Ewing and Smith (1917), assuming that a high moisture content of the feces was indicative of a rapid rate of passage, concluded that rapid passage was associated with high digestibility. No actual determinations of the time taken by food to pass through the gut were made, however. In Balch's (1950) study the vari- ation in digestibility coefficients from period to period were not large and could not be eXplained by differences in pas- sage. The range of digestibility coefficients obtained by Makela (1956) was similarly narrow even though the range of dry matter intake was comparatively wide. As a result an increase in the time of retention by 24 hours was attended by an increase in digestibility of the dry matter by one per- centage unit only. The variation in digestibility coeffi- cients encountered by Blaxter gt_gt. (1956) with sheep was 0 Ir : 3313853? t»- ‘ a "“1215 :56 ;( -‘ “v; ”3 we“ " H‘ Xoht . fitt'fio Q. u;‘ {.1- iw - tux; . 1 ~. . ’0' W0 n 5: on h‘ .4" T)? F 4.3." ‘u .“3. ‘ (7 2" “c ‘r‘. ’3... g 3' :3: o” in. ~ . . a “1 9:9: ‘-""33 S. . a \ - ‘L: .,_ 56 much greater than those observed in previous studies. An in- crease in the feeding level of dried grass from 600 to 1200 grams was accompanied by a very slight fall in the digestibil- ity of long material, a distinct fall in the digestibility of ”medium“ cubes and a considerable fall in the digestibility of the "fine" cubes. These results closely paralleled the passage studies since those rations that spent the greatest time in the alimentary tract were digested to the greatest extent. The absence of a marked correlation between digesti- bility and rate of passage in previous experiments undoubtedly arises from the limited spread of rates of passage of the foods compared. A mathematical analysis of the relation be- tween digestibility of the food and its rate of passage through the gut indicated that the former could be predicted from the latter. The constant describing the time course of digestion showed that about 70 percent of the digestive process was completed in 10 hours for the particular grass used. Regulation of Passage through the Alimentary Tract Information concerning the physiolOgical regulation of the passage of ingesta through the alimentary tract of the ruminant is relatively limited. The basic movements of the various segments of the tract and their role in the course followed by ingesta through the tract, as well as the im- od‘w xrw of t :test. in is await-is s' a l (4.3» 'n ".‘u 'a; I: “:1 t" it so. u :‘M‘ 0 . .x. vs.- I l. ‘. "nun. ‘Ag "1 ‘5“. .‘ .1-— cm., ‘ULV‘ \ |:. ‘ l \52. \ ‘. c 5 \ . .n. '3‘! 57 portance of the physical make-up and specific gravity of the ingesta in determining its arrangement have been discussed in a previous section. Most investigators agree as to the coordinated action of the first three stomach compartments in the transfer of in- gesta from the reticulum to the omasum and the prevention of its back flow from the omasum to the reticulum (Schalk and Amadon, 1928; Phillipson, 1939; Dukes, 1955; Clark, 1956; Habel, 1956; Benzie and Phillipson, 1957). In a normal cycle of contraction of the reticulo-rumen the reticulum usually exhibits a double contraction at the rate of about 60 per hour under resting conditions. Mbvements of the reticulo—omasal orifice and the omasum have been shown by Balch gt g. (1951) to bear a constant and characteristic relationship to the pressure changes in the reticulum. The pattern was found to continue without interruption when the animal was resting, eating, ruminating, drinking, lying down or being milked. The frequency of the cycles of contraction of the reticulum and omasum was greatly increased during eating (105/hr.) and some- what reduced during rumination (50/hr.). Similar observations have been reported by Schalk and Amadon (1928) and Balch (1952, 1958). The reticulo-omasal orifice appeared to remain loosely Open during most (60-70%) of the cycle of reticulo- ruminal,motility (Balch at. gt, 1951). Schalk and Amadon (1928) and Balch gt gt. (1951) studied I I .‘fiq’vv 'I :2 .thh“ d‘-:! I n1 L .1 u. t It I I" {I ,D- n \I‘ “O..‘H‘V‘. \ ' 1““3!‘ ‘Mg 'no-vh may I.' . ‘ ‘Y‘ I n.‘_| .“ E‘ u to; . ~ .‘I “in-i lie. ~a'gfi?!0 ." ‘.J a a.:, A.pfizpi 58 the motility cycle of the reticulum, reticulo-omasal orifice and omasum of cows by palpation and pressure recordings. Phillipson (1939) and Benzie and Phillipson (1957) have de- scribed the movements in sheep as seen in cine—radiographic film. In each cycle the reticulo-omasal orifice was closed during the first reticular contraction. During the second contraction the orifice Opened and the omasum moved downward and forward. There appeared to be a sudden fall in pressure in the omasum at this time and an influx of ingesta from the reticulum. Most investigators seem convinced that the ingesta is drawn into the omasum and not simply forced in by gravity. This concept is supported by Balch §£.§l- (1951) who estimated that a pressure gradient of perhaps 10 mm. Hg. exists between the reticulum and the abomasum during the last reticular con- traction. As the reticulum relaxes, the omasum begins to con- tract and the reticulo-omasal orifice closes strongly. The dorsal pole of the omasum appears to eXpand forcing the semi- liquid ingesta between the laminae. During contraction the more fluid ingesta can be seen running rapidly along the omasal groove to the abomasum and at the end of the contrac- tion a mass of more solid material appears to move slowly from the lower end of the omasum into the abomasum. In view of available evidence it seems reasonable to assume that passage of ingesta through the reticulo-omasal (orifice to the omasum occurs at a definite stage in each cycle I O I. CJSZI‘EC. :5 relative ~.. N “a ’3' ‘\\ 3 ,. . ~31 -ns 59 of contraction and that passage from the reticulo-rumen will be relatively continuous throughout the day. Several factors appear to be involved in the control of passage from the reticulo-rumen. The frequency, as well as the extent to which the reticulo-omasal orifice Opens and closes, seems likely to be of considerable importance, particularly in effecting an accelerated passage during eating. Recent studies of Balch (1958) lend support to this premise. Titchen (1958) has shown that stretching or pressure on the walls of the reticulum in- creases contraction frequency of this organ. This suggests that increases in reticulo—rumen volume due to eating, drink- ing or salivation accelerate passage by increasing forestomach motility. The fact that hay does not increase the rate of passage to as great an extent after eating as concentrates indicates that the consistency of the ingesta in the reticulum is important in determining passage into the omasum (Phillip- son, 1952; Balch, 1958). In addition to the intrareticulo—, ruminal factors Titchen (1958) found that reduction in the pH of the abomasum to between 0.9 and 1.0 was effective in the stimulation of reticulum contractions. This is lower than the pH of 2.3 - 2.4 reported by Masson and Phillipson (1952) for the abomasal contents of conscious, fed sheep but is similar to the figure of 1.05 - 1.32 for the secretion obtained from a Hollander pouch prepared in the abomasum. Inhibition of reticulum contractions by distention of «'H‘Aw r ' “5 n-hit u "rcng‘iarc uI-II-n ~‘I.4ut. LE: 3239315 I Lie): cor' ‘"‘"‘ «u n...” ‘ (:I"°: ‘n ‘ I‘. '. "3““ gr '~""- .00 4' not, ‘ ‘ I: “Wire. m .Zfi‘a I .Z_‘§:‘ 60 the abomasum has been reported by Phillipson (1939) in the conscious sheep. Similar results were found in decerebrate preparations of sheep, goats and calves by Titchen (1958) who also observed that manipulation of the pylorus profoundly in- hibited contractions of the reticulum. This inhibition re- sembled in many aspects that arising from distention of the abomasum and, as Titchen pointed out, was probably similar in its nature. There is no evidence as yet to show that movements of the forestomach are directly inhibited by intestinal reflexes. In spite of several methods of investigation the move- ments of the omasum as well as the means whereby ingesta is passed through the omasum remain obscure. Benzie and Phillip- son (1957) have Observed obvious and regular changes in the disposition of the omasum but could not relate changes in shape Of the organ with the remainder of the pattern of activity of the stomach. 0n the other hand pressure changes that have been recorded from the interior of the omasum are as regular as those in the reticulo-rumen and are related to them in time (Balch gt g;., 1951). These authors have specu- lated that transfer of ingesta from the reticulum to the abo— masum occurs in two stages, controlled by a valve-like action (of the omasum. Cine-radiographic studies of sheep strongly suggest that a differential passage of liquid and solid in- ggesta.takes place through the omasum (Benzie and Phillipson, 1:15;? 3:1 '1‘. Man .1: ‘ 9a {“715 ..'. .c 1" q...“ t 'Y \ II ;.. .'i 63 I Yo ‘433‘3. "new 1"! .. H n. c' ‘ " 9:. ‘ “N‘s I“ :9!“ .’ :,:“ ““‘U~g..‘ I ‘~: m.“ V ’c' 1“ ~‘ (‘91 "I .‘ ‘ “ 24 61 1957). Flow of ingesta from the omaso-abomasal orifice indi- cates that passage from the omasum to the abomasum is rela- tively continuous (Bouchaert and Oyaert, 1954). Schalk and Amadon (1928) were of the opinion that the flow of omasal in- gesta into the abomasum was accomplished chiefly by the force of gravity. The postero-ventral position of the sulcus omasi lends support to this premise. It has been provisionally assumed that the movements of the abomasum conform to the movements which take place in the stomach of most species. Dukes and Sampson (1937) have ob- served that contractions of the abomasum in sheep resemble those seen in the simple stomach. The fundus was usually quiet while the corpus exhibited numerous contractions and relaxations. Very little movement of the corpus has been ob- served in radiological studies of abomasal motility in mature animals (Phillipson, 1939; Dyce gt gt., 1953; Benzie and Phillipson, 1957). There appears to be general agreement among investigators that the pyloric part shows strong peri- staltic waves which pass right up to the pylorus. At times several of these may be in progress simultaneously (Dukes and Sampson, 1937). Phillipson (1939) was of the opinion that the corpus was raised by the contractions of the reticulum and that some of its contents were passed onward into the pyloric part, ini- tiating peristalsis. FluorosOOpic observations have shown no at O . 1t»: a. per. zVU ‘01 "" “ass V u.‘.i a, :.:.;.C M n. . Q: “1 .521: ye I . e . t;- a? a PI ‘ 3 v‘ " s..: L', :‘lein‘ s.;: I s ‘m; huh , I I.\.‘ ‘v n F ! |_H‘el 5.9:. 1": . F 62 apparent relationship to exist between abomasal motility and that of other parts of the stomach. Balch gt gt. (1951) have substantiated this independence by pressure recordings. According to Dukes (1955) ingesta entering the pyloric part of the abomasum is carried distally with each successive wave of peristalsis. At frequent, irregular intervals ingesta from this viscus is forced into the intestine by these peri- staltic contractions. Normal evacuation of material from the abomasum requires an adequate pressure gradient from the abo- masum to the duodenum. Benzie and Phillipson (1957) observed that, as ingesta arrived at the pylorus, the anterior duodenum relaxed to receive the material. A total contraction of the duodenum immediately past the pylorus then occurred and forced the ingesta onwards. It has been known for a long time that if the ingesta leaving the stomach of the dog is allowed to drain from the proximal duodenum through a fistula the stomach empties more rapidly than normally. Re-introduction of the ingesta so obtained into the intestine beyond the duodenal fistula proe duces a normal emptying time of the stomach (Alvarez, 1940). The experiments of Phillipson (1952) indicate that the same principle is true for sheep, for the re-introduction of the ingesta collected from the abomasum or first part of the duodenum into the lower part of the duodenum reduced the rate of flow from the abomasum. Distention of the duodenum or I . . 514115.951 ‘ 17“ r when- i ‘ ‘ . :. 1:2 as: t: reticu; w'r ‘ ~ g‘. “Ina“.b “ Tit": m,” 'r ... 23‘ 2!, as “- m- a I [4' ‘l , 63 small intestine of the dOg (Thomas, 1957) as well as the sheep (Phillipson, 1952) inhibits gastric emptying while distention of the abomasum of sheep inhibits the passage of ingesta from the reticulum (Phillipson, 1959). The profound effect of mechanical distention on gastric evacuation observed by many investigators led Alvarez (1940) to conclude that this factor may have an even greater effect on the rate of emptying than has the chemical composition or physical prOperties of the in- gesta. In addition to mechanical distention several other fac- tors regulating gastric emptying are known. Thomas (1957) has recently reviewed the literature pertaining to this subject. The effect of the physical state of food on gastric emptying has been repeatedly demonstrated in monogastric animals al- though this factor has not always been distinguished from accompanying chemical differences. Non-irritating liquids leave the stomach more rapidly than irritating liquids; finely divided ingesta leaves more rapidly than coarser ingesta. The concentration of soluble constituents in the food has a marked effect on the rate of gastric emptying. One of the earliest established facts in this respect was that physio- logical saline leaves the stomach faster than either hypotonic or hypertonic salt solutions. The delaying effect of hyper- tonic or hypotonic concentrations of salt or various sugars 1188 been.confirmed by all subsequent investigators. ‘ 1 239338. «a! 3"1 low-to I .uhr :94"? VC “1" .nuu . .. ‘ I "I :H' {r . n- .9' guy ‘ no.0 W! *l‘ :i.\ J. 1"... h V“- ‘4 U. 39.5“:.‘ pv- Jfi" 'anh it" 0‘ '. .‘ ‘0'. id : \o 21.5- a?! z a “'V 'l .xslike I 5":qo "‘ vb b 64 Several early investigations indicated that the rate of gastric emptying is related to the volume of gastric contents. Recent work substantiates this observation and indicates that for any individual and type of meal, the amount evacuated per unit of time is a function of the volume of gastric contents. The profound effect of acid in the intestine on gastric evacuation is well established. This suggests that the reac- tion of gastric contents may influence emptying time. Avail- able evidence indicates that acids or alkalis in concentra- tions likely to be encountered in the ingesta have little or no effect on gastric emptying. The characteristic effects of the major foodstuffs, car- bohydrates, proteins and fats, on the rate of gastric emptying are likewise well known. Fats leave the stomach slowly where— as carbohydrates leave relatively rapidly. Proteins pass from the stomach much faster than fats but at a somewhat slower rate than carbohydrates. Singleton (1951) studied the effect of the duodenal contents on abomasal activity of goats and observed that the introduction of emulsions of olive oil or peanut oil and sometimes two percent solutions or suspensions of proteins or their breakdown products inhibited abomasal activity. It is readily apparent, from the literature cited, that only limited evidence is available concerning the mechanics and regulation of the passage of ingesta through the ruminant aw . . ' :53:- o... t .I éolu ' "F “.1: 6 'uv senile to ..~-.-‘ MN; .--':6 UQA‘ . "W ’n .‘r a...‘ . g. I: I.".‘ flu“\ 'Otlb‘.‘ .-:=.' F. ‘..\.._' ..i ”01‘ ‘ ‘ "1 afigh .. '1‘... V a.“ ,‘n V. . ‘n it! b. 65 stomach. This is particularly true with respect to the activ— ities of the abomasum which have provisionally been assumed to resemble those of the simple stomach. There are two funda- mental differences in this regard that appear worthy of men- tion. In the ruminant it may be considered that the abomasum is continuously being filled and is never normally empty whereas in the monogastric material arrives in the stomach only at the time of eating and may, in some instances, be com- pletely evacuated before the next feeding period. In addition, ingesta entering the abomasum is finely divided and has had a considerable portion of its dry matter removed by absorption prior to this point. Such is not the case with the simple- stomached animal which must rely almost entirely upon mastica- tion for the division of its foodstuff before entering the stomach and upon absorption in the intestinal tract for re- moval of its end-products of digestion. What effect these differences have on regulatory mechanisms in the ruminant is largely a matter of conjecture. Movements of the small and large intestine and passage of ingesta through these segments of the alimentary tract have been adequately described and discussed by Alvarez (1940) and by Dukes (1955) and hence will not be included in the present terms of reference. Vh.: l!‘;‘oo:: 3' “ \ Ab-J.~ 0 s Aug," 5 ‘J’A. Ii. 5‘ . ‘: 'S’mwl r C ., “L“ -‘.\ " “Ft“. F ‘h . I "" ~§~ .It k: 5"‘ar § "VI|‘-‘ vet“ I}:- :hg‘up ‘I‘ "t" (1&- -..~ ‘ J. ‘. "v‘ .- I ‘ ‘9”: :- I“ ‘\ M ‘o n a ‘v ‘3‘"; I! \..‘. ' fi .' C's, 0v.:‘.:c 66 Changes in the Ingesta Passing through the Alimentary Tract Methods of investigation Quantitative digestion in the entire alimentary tract can be determined both directly by the conventional digestibility trial and indirectly by the ratio technique. The conventional method is widely used and, in general, has served as a basis of comparison for the other methods. The various sapects of the conventional method of determining digestibility have been adequately discussed by Armsby (1917) and Maynard and Loosli (1956) and will not be considered in any detail here. More recently there has been an increasing interest in the use of the ratio technique because of the expediency of the method. The ratio technique involves the use of an "inert reference material” as an indicator. Ideally such a substance should be totally undigestible and unabsorbable, pass through the tract at a uniform rate, be readily determined chemically and preferably be a natural constitutent of the feed consumed. By determining the ratio of the concentration of the refer- ence substance to a given nutrient in the feed and in the feces, the digestibility of the nutrient can be determined without measuring either the feed intake or feces output pro- vided representative samples can be obtained. Coefficients of digestibility are calculated by the following formula: 67 indicator in feed Digestibility = 100 f (100 églndicator in feces x % nutrient in feces arnutrient in feed Thus far, chromium sesquioxide (Cr203) has been found the most satisfactory of the exogenous indicators (Coup and Lan- caster, 1952; Lambourne, 1957a, 1957b; Corbett gt gl., 1958). Marked irregularities with time in the fecal concentration of Cr203 during periodic Cr203 administration have been repeated- ly described (Kane ££.£l-. 1952; Raymond and Minson, 1955; Smith and Reid, 1955; Kameoka gt 51., 1956; Pigden and Brisson, 1956; Hardison gt gl., 1956; Bloom 91., 1957; Lambourne, 51., 1958; Putnam gt gl., Is In 1957a; Balch gt 51., 1957; Corbett 1958). Variable marker excretion by ruminants probably arises from a differential and uneven passage from the stomach, par- ticularly the reticulo-rumen. Large variations in Crgoa con- centrations have been found by NcGilliard (1956) in samples of ingesta taken from the duodenum of a steer dosed with capsules containing this marker, larger variations, in fact, than those found in the resultant feces. Balch g; 3;. (1957) found great- er variations in Cr203 concentrations in ingesta.passing through the reticulo-omasal orifice than in the feces and sug- gested that ingesta undergo some mixing after leaving the reticulo-rumen. The data of Balch §£.§l- (1957) and Lam- bourne (1957a) indicate that differences in concentration were sates! when E 1:23 5911]. t a” , u. “Na: 9 ~...I a". J 5“ . a (n ' A D rn O ‘- >l "=0 ‘9 ’T‘ ‘5.) g“ h. t“ \r‘ A -~~-..~..'“U'9' ., ‘ .3 : ’glant‘ “WWHV ' > I H \ E t “ '8‘ \ s .. V- ‘5 ~99? I i I. .,. r “I '1‘. ‘ s . a. H ‘b‘e 3 as ”war. w.‘ a :‘O. .1. ‘ _ ‘ ¥‘~"$ 'N 4 .oz.‘ ' .5 o . ~ . ‘ a, .v- ‘ .‘ .55. ‘3 as \' p: \' I‘ .z .‘ ‘ . \“ ‘A 68 greatest when Cr203 was given in concentrated form once or twice daily. 0n the other hand Pigden and Brisson (1956) and Brisson gt gt. (1957) observed that sheep and cattle excreted Cr203 very evenly when it was administered at four hour in- tervals in six equal daily doses. Balch gt al- (1957) found that once the Crgos had become mixed with the ingesta of the reticulo-rumen the amount present declined at much the same rate as the dry matter of the ingesta. Density of the marker is apparently of no importance as long as particle size is small (Raymond and Minson, 1955; King and Moore, 1957). Lambourne (1957a) observed that approximately four days were required for a dose of Cr203 to pass through the ruminant alimentary tract. A preliminary Cr203 administration period of from seven to ten days has been considered sufficient (Edin gt gl., 1944; Hardison and Reid, 1955; Smith and Reid, 1955; Kameoka _t _;,, 1956). The length of the collection period has not been well defined, however, most investigators have obtained reasonably good results when sampling the feces twice a day (12 hour intervals) for five days or more, the accuracy being increased somewhat with the longer collection periods. Several research workers have compared the digestion co— efficients calculated from the lignin concentration in the feed and feces with those obtained in the conventional manner (Kane gt gr, 1950, 1952, 1955; Balch gt g_1_., 19545; Richards gt gt,, 1958). On the whole there was a reasonable degree of v'w‘ty betwe 1~~ 1. -. ff tamer t) I». v . o -‘ 2 9t 91. l. ”I. 7, 5“ 9’ a) 3:71. 11min c is: leaves 9: vu._ .I ‘ ””5' It 8;? I; "~°.. .. 0.5.: _E e,- 69 conformity between the results obtained if the lignin was assumed to be completely indigestible. The use of lignin, however, is subject to several disadvantages. Various degrees (0-26 percent) of digestibility of lignin have been reported (Hale gt g;., 1940; Ely gt g;., 1955; Balch gt g;., 19545; Miller gt gl., 1954; Salo, 1958). According to Salo (1957a, 1957b) lignin occurs primarily in the stalks and in parts of older leaves so that its distribution in feed is not homo- genous. It appears to be distributed equally irregularly in the ingesta and feces, and is excreted just as rhythmically as Cr205 and other inorganic indicators (Kane gt 31., 195?, 1955; Reid, 1952; Raymond gt g;., 1954). Salo (19579, 19575, 1958) has recently pointed out the lack of agreement with re- apect to the reliability of the procedures for the determina- tion of lignin and has reviewed the literature pertinent to this subject. This disagreement undoubtedly stems from the fact that lignin is a conventional polysaccharide mixture of varying composition. In an attempt to avoid some of these difficulties Richards and Reid (1952), Anthony and Reid (195a) and Richards gt g;. (1958) have, instead of lignin, used its constituent methoxyl content, which is more readily determined and defined chemically. According to Ely gt gt. (1955) and Salo (1958), however, this substance, too, is sometimes partially digested. Reid gt gt. (1950, 1952) introduced the use of fecal ments or chm“ arsofdigest :95} and 9. (Trims thick ‘2 attentions? 1:572 in has a (lastly mpg 133.5, 115% bee “'3: .3, Run! I.‘e eff‘ fins-(‘1 0 :..-.)J:‘V$:n c. "N, I” “’Av~¢i “INC. Gui-1“». ‘ e '3: \h ‘ ' I "l.,.. I ‘“~~3ris 53. . “a .h ‘ .‘ ‘ ‘ ., W _a. I; "Y ::?QH§ . -yu“b (:31) )5.” Z" , V “:2 a, 70 pigments or chromogens measured at 406 my as internal indi- cators of digestibility. By using similar procedures Kane gt fil’ (1953) and Raymond gt gt. (1954) obtained digestion co- efficients which conformed quite well with those determined in the conventional manner. Digestibility figures obtained by others who have employed the chromogen method have been con- siderably more variable. Criticisms, which are not without basis, have been expressed by Brisson gt gt. (1954) who ques- tioned the effect of stage of maturity of the plant on the composition of the chromogen mixture and by Davidson (1954a, 1954b) who observed that the majority of the chromogen mixture in fresh and dried green forage contained chlorophyll, with varying quantities of xanthophyll and carotenes, whereas in feces phaeophyten a and b were the main constituents. As a result Brisson gt gt. (1954) altered the analytical pro- cedure to make allowance for this discrepancy. Despite the improvements made in the original determination Brisson §£.§lo (1954) were of the opinion that the fluctuating quantities of porphyrins in the feces make it improbable that one defined wave length could be found which would make it possible, in all instances, to measure the chromogens in grass and feces without error. In addition, variations in the excretion pat- tern of chromogens similar to those reported for both lignin and Cr203 have been obtained by Hardison gt_g;. (1957). The disadvantages of lignin, methoxyl and chromogens thus appear 1 1' ‘2 rare or i a ”*2 use 0. :2: :ecmr a; '.O on, L 5331' ‘33 ,, I c H V"?.D‘ F? k", "-le .‘V “U “h- . 1| ‘ . . "' " Mr A , who; LL; H “e 'u 5:- hung (an. n. “4ng Lb. t l V . Euroc Te Una: \‘ I.” J; Cf :2.) '5': £2“; «0* ..' ’ . "‘ E a. ‘7 .536“ . :0{ "“12 c g s r“ ‘ 71 to be more or less comparable. The use of a water-soluble polyethyleneglycol (PEG) of high molecular weight (4000) for tracing the flow of water and solutes from the reticulo-rumen into the omasum has been reported by Sperber gt gt. (1955, 1956). These investigators could not detect any absorption from the gut or any effects on the rumen micro-organisms. Hyden (1955b), using a turbid- imetric method of analysis (Hyden, 1955a), studied the excre- tion of PEG when single doses were administered directly by fistula into the rumen or abomasum of cattle and sheep. He obtained a mean recovery of 93 percent and suggested that the apparent losses of PEG were due to some destruction of the material during its passage through the alimentary tract. Corbett gt gt. (1956) obtained low and quite variable re- coveries of PEG when this substance was fed in grass-cube meal to grazing cows. Subsequent studies by Corbett gt gt. (1958), in which both.PEG and Cr203 were incorporated in the grass cubes, confirmed many of the earlier findings. Recoveries of PEG were low and the excretion pattern varied to a much greater degree from the mean than did that for Cr205. It was concluded that the uneven excretion in the feces arose mainly from uneven mixing with ingesta in the reticulo-rumen and that the distinct patterns of excretion of the two substances arose from their differential distribution and passage in this part of the gut . Emu-r" ?I “1.49. U _ here- o«. U. '. O O: I 0".5‘7 V . . odg‘op “A :..:..‘..}' ;,v "-::“'nr fr .Ozv'ioyh V . 0 u 2": f!,‘ At»; a. _. a. 5.: N""p: I) W... 4: u: It. '0 in n 72 Quantitation of digestion in the various segments of the alimentary tract, particularly the reticulo-rumen, is con~ siderably more difficult than the estimation of the extent of digestion for the tract as a whole. This is due in part to the anatomical complexity of the ruminant stomach and in part to the dynamic processes of the reticulo-rumen, for in this organ intake, passage, absorption, fermentation, addition of saliva, synthesis and the transfer of substances through the rumen wall from the blood often occur simultaneously and con- tinuously. Further complications arise from the heterogeneity and stratification of the rumen mass. As a result representa- tive samples and time-sampling relationships are difficult to obtain on a quantitative basis with any degree of certainty. The use of the rumen fistula as an investigational aid is not new. Colin successfully used the open rumen fistula as early as 1886, and it was soon ad0pted by a number of other investigators to study motility of the rumen and other fore- stomachs. It was not until after Schalk and Amadon (1929) closed the fistula with a block of wood that this method re- ceived widespread adoption as a means for studying digestion in the rumen. Since then descriptions of various methods have been presented for establishing closed rumen fistulas in sheep, goats and cattle (Quin gt gl., 1958; Phillipson and Innes, 1959; Balch and Johnson, 1948; Jarrett, 1948; Dougherty, 1955). Similarly, descriptions of various types of rumen :tiae have 1 2:: =:.:‘ Inf-.25 'I “hL-ov- - n; ‘4’. g..- 0“" I no 'o-gan ¢‘, :1 1.... fi-» bl; :’=,“: | "‘“ '“uvu vs, "f ""‘M:‘ " -“~'~.e‘~ v "Il\‘- O 2,. 'i“ r U (I D (D “D 1 9 I u..:“:e S‘J I ., '04. a. .- U“§uE “3“ ~ :b. . I. II“ n M.“"’ -. ' I .I ‘1 ‘IA 'v 75 cannulas have been presented by Quin gt 21- (1958), Phillip- son and Innes (1959), Jarrett (194a), Hentschl gt g;. (1954) and Dougherty (1955). Most investigations involving use of the rumen fistula have been devoted to a study of the qualita- tive aspects of digestion. In recent years, however, increas- ing interest has been focused on the use of rumen fistula methods for quantitating digestion in the reticulo-rumen. Hale gt gt. (1940, 1947a, 19475), using lignin as a reference substance, studied the extent of digestion of alfal- fa hay in the reticulo-rumen of the cow. After a preliminary feeding period of at least 12 days samples of ingesta were obtained from the reticulo-rumen of fistulated cows by com- pletely removing, weighing, mixing, sampling for chemical analysis and replacing the contents prior to feeding, six and 12 hours after feeding. Coefficients of rumen digestion were calculated by applying the lignin-ratio technique. These co- efficients are not entirely commensurable with coefficients of total digestion. The latter coefficients include only the percent of nutrients which have been absorbed and do not appear in the feces. On the other hand coefficients of rumen digestion encompass not only the percent of nutrients which have disappeared due to absorption but also those which have passed from the reticulo-rumen to the remainder of the all- mentary tract. In order to definitively equate the two groups of coefficients the assumption must necessarily be made that o 9’." F,“ ‘16 hye‘liia ‘ 1 W‘s-m". .c'OVv u. 4'. ‘ LE ”use “a In § ‘ -.W. ”03' do u U U‘ '0- (“sqg‘d «.3. ‘ “011 C N”. .0 ‘1" L" ‘0 and, 37-“ .,3 14's. "\n s ._‘ -‘. at .“¢;“:‘ 3. \' ces‘ '1 '2“ ~ ’vq‘ .5 s \‘ .q ‘a.. F ‘i I ~‘:=§:. "-,, rut ~ ‘\ 4. ~' I ‘A ‘.D ‘,- QJ' \. \".n‘ .“. - l- ‘l \ 1‘, V ll 1\‘ A‘- vq $ V “:‘H {‘1‘ 74 the concentration of lignin in the ingesta leaving the reticulo—rumen at any given time is identical with that of the ingesta remaining in the reticulo-rumen, a premise which has not been eXperimentally validated. In fact, from a con— sideration of the passage of foods through the alimentary tract of ruminants it seems highly improbable that such would be the case, particularly if the diets fed contained materials of widely different densities. Using the lignin-ratio method on ingesta from different segments of the alimentary tract of sheep, Gray (1947) studied the progress of cellulose digestion along the gut and obtained good agreement between the values for each of four sheep.’ In general, the following procedure was employed for determining digestibility. The sheep were fed on a constant ration for a suitable period of time and then slaughtered. Successive segments of the alimentary tract were ligated and samples of ingesta were taken from each compartment for chemical analysis. The principle used in determining digestibility in the differ- ent segments was the same as is usually applied in the deter- mination of total digestibility. For example, in determining digestibility in the reticulo-rumen cellulose-lignin ratios of the food were compared with the correSponding values for ingestain the omasum. Paloheimo gt gt. (1955) were of the opinion that the results obtained by this technique are in- fluenced to some extent by the time elapsing between the last _ , a 1:52.22 in t. 1222229 at the I‘fé‘ufi 9*" Q p " l‘tl‘ 3:9 w. ”'53 1531211: '3-‘5? an“; . .. 75 feeding and slaughter of the animal and that it is possibly unwise to use omasal ingesta for determining the extent of digestion in the reticulo-rumen because of the differential passage of the solid and liquid fractions through the omasum. Paloheimo gt gt. (1955) and Makela (1956) have applied essen- tially the same method to study the digestion of N-free or- ganic matter in the ruminant stomach but sacrificed their animals midway between feeding times and applied the lignin ratio technique to samples of ingesta from the abomasum rather than from the omasum. This technique was subseQuently adopted by Gray and Pilgrim (1955) and Gray gt gt. (1958a, 1958b) to study the progress of carbohydrate and nitrogen digestion along the gut of sheep. After feeding, however, the sheep were slaughtered at various times throughout the day. Again, the validity of the procedure used for calculation depends on the abomasal samples being representative of the ingesta pass- ing through the abomasum during the entire period of the feed- ing cycle. Furthermore, the method is not generally applic- able because of the need for slaughter. Balch (1957) has pr0posed a third method for obtaining samples from which to calculate digestibility coefficients for the reticulo—rumen by the lignin ratio method. Cows with large rumen fistulas were used on the experiment. The sampling procedure was based on two major assumptions: (1) that the ingesta in the reticulum adjacent to the reticulo-omasal ori- “a m a com: nu “JV 0...“..p "fie O‘l‘ -.:i‘-I tee a «L '=‘*‘ulo-r‘i uc c‘y'.‘ Hi. '5‘“. ‘q f by H.01243uU e I u‘ , mam-192‘. oz in ‘1 ¢ .123. 03.14139 a 'i ‘- i 1 2.3.3315 0f ) "' ‘0: a a.‘ .I’ 3"“.Cier ';.'F‘l' "we I: 1 I11“ 0‘ TN. {'2 “(NM V ..‘. a‘ .. QME 3‘3): 9“‘ | ‘1‘ r. , . 3h '5 .‘ V. \ h‘e gt 'V. ll ‘.- I‘ . v- ‘Jau? 5 K v ~'.' s . ‘g‘Aa‘ t V ::‘9 i I .ECfi .‘ ys‘ a“. \E In. ‘ i535; _ v“; 1. (‘31:, v. Q A .2 x, {g s; \\: 76 fice has a composition closely similar to the ingesta passing through the orifice and (2) that the passage of ingesta from the reticulo-rumen is relatively continuous and constant throughout the day except during eating when considerable acceleration occurs. Samples of the ingesta near the reticulo- omasal orifice were taken daily at frequent intervals through- out periods of 5-12 days and then combined. Rumen digestibil- ity coefficients were computed by applying the lignin ratio technique to the composition of the combined sample. Balch was of the opinion that the composite samples were represen- tative of the ingesta leaving the reticulo-rumen but pointed out that experimental evidence to substantiate this is lack- ing. Although this sampling procedure is a dynamic approach to a difficult problem it still remains subject to many of the same criticisms and limitations of the methods previously dis- cussed. The use of re—entrant fistulas in the abomasum-duodenum or the proximal duodenum to directly measure ingesta passing from the stomach appears to offer a more precise method for obtaining quantitative measurements of the disappearance of food from the alimentary tract and of the appearance of syn- thesized products that are not digested or absorbed before they reach the small intestine. This method has been used for a number of years in the monOgastric species and its applica- tion in the dog has been described in detail by Wasteneys gt . 'c!“ J L- fivel' . ‘ .f:..‘lp‘v “1"“ I ’ ‘ ..'J. I 3:11.12 .1 9.3.9 11316: Km"? 1! "' "' CI. d .l ‘.A -‘ § -" I tn" '5 .‘L N “ d:~ f;- \t 77 gl. (1941). Use of the technique in ruminants has been con- siderably more limited. Young (1951) described a technique for establishing a simple duodenal fistula in a 700 pound steer in which the eleventh rib was resected and the periosteum was used for sub- sequent osseous deposition thus strengthening the fistula area. McDonald (1953) modified Young's technique and success— fully established duodenal fistulas in sheep. The operation has been illustratively presented by Dougherty (1955). Dougherty and Cello (1949), in studying absorptive processes in the alimentary tract of sheep, employed an abomasal-duodenal-shunt fistula which was patterned, for the most part, after the technique described by Markowitz (Crocker- Markowitz fistula) (1954). Similar preparations for measuring the passage and composition of ingesta from the abomasum of sheep were used by Phillipson (1952) and Masson and Phillipson (1952) but were not entirely satisfactory. As a result these investigators eventually adopted a method in which three can- nulae were inserted into the duodenum, one immediately caudal to the pylorus and the other two in thelower part of the duodenum beyond the common opening of the bile and pancreatic ducts. Ingesta was continuously collected from the first can- nula, and after measuring and removing a sample it was warmed to body temperature and reinserted slowly into the duodenum through the third cannula. Relatively large volumes of in- {€315 NETS 1:) 1.0:; ..")n- r“ .5 , i... a» so. ,.9‘ fi '= 3 .2 ht... q! ‘_., :‘.‘."‘55 001'“ b-.A:p..- “= “-"“-|.. . g .04" ‘ ...i.,'n C? t g: .‘n .3“ “g 3‘ 33'. ‘_ ‘. A . x n s ‘1) .5. ‘ “a .v- ‘ I“: ' .-. '13! a 'c J 42‘ 3‘1 ‘ ‘w ‘ Is. s. ‘ 5‘-‘ 78 gesta were re-introduoed within 12-20 minute periods. Back- flow along the duodenum was prevented by inserting a small balloon through the second cannula and inflating it suffi- ciently to close the lumen of the duodenum. This method has a serious disadvantage in that inflation of the balloon in the duodenum reduced the output of ingesta from the abomasum. Re- duction or temporary cessation of flow from the abomasum was likewise observed whenever ingesta was re-introduced into the duodenum. Passage from the abomasum was considerably accel- erated if the ingesta were not re-introduced. Hogan (1957) employed the technique of Wasteneys gt gt. (1941) to exterio- rise the flow of ingesta in sheep either in the first part of the duodenum or in the terminal part of the ileum. The total ingesta passing from the duodenum or from the ileum was col- lected over a 12 hour period. A sample was taken from every 50 m1. collected and the remainder was re-introduced slowly into the gut beyond the exteriorization. The quantity of water, dry matter and nitrogen passing through the duodenum and terminal part of the ileum were estimated by this means. The re-entrant fistula technique appears to offer sev- eral distinct advantages for quantitatively studying digestion in the ruminant. Ingesta passing from the stomach can be totally collected and as a result digestibility coefficients determined directly. Representative samples and time-sampling relationships can be obtained on a quantitative basis with a 1223:1591 Ire u”'fi n’s f . ""‘Ob. u I .. We: .v. 4‘ .v . "I::§.-fl . "'I- a “-1.33 1 79 reasonable degree of certainty. Digestion in the stomach and intestinal tract can be partitioned by comparing digestibility coefficients for the stomach with those for the entire ali- mentary tract, coefficients for the lower gut being computed either directly or by difference. Kameoka and Morimoto (1959) have studied the extent of digestion in the rumen-reticulum-omasum, using goats whose forestomachs were separated from the abomasum. By this means ingesta passing from the omaso-abomasal orifice was quantita- tively collected, sampled and the remainder re-introduced into the abomasum. These investigators were of the Opinion that this was a more apprOpriate method for studying rumen digestibility than was the re-entrant duodenal fistula tech- nique. The two methods are, in principle, much the same, however, for little or no absorption of organic matter occurs in the abomasum. In fact, this method would have the serious disadvantage of the fistula being more difficult to establish and considerably more tedious to maintain over a prolonged period of time. Water and dry matter In studies dealing with quantitative changes of the in- gesta during its passage through the alimentary tract it is initially essential to consider some of the dynamic aspects of water-dry matter relationships in the various segments of 157.??Ct- If )‘igit (1915) f 55-32 for shee :fizgesta in ( :ser."re all? be ‘3. 5‘“ cu‘. m) - '0 A I r; 9“:‘ “HQ. k. *0»; V‘AIU gnu”; 1 5" ' ‘ V‘y OVA; "9” .1“. ” 0 .: a ’13“: “H“ (Lu- ’1". mule-ture: 80 the tract. If one calculates, from the data of-Ewing and Wright (1919) for steers, Makela (1956) for cows, Boyne gt g1. (1956) for sheep and Rogerson (1958) for sheep, the quantity of ingesta in the reticulo-rumen relative to the quantity in the entire alimentary tract, it is seen that the ingesta in the reticulo-rumen accounts for approximately two-thirds of the total contents in the tract. This value appears to be relatively constant and independent of the level of dry matter intake. Hale (1939) emptied and weighed the contents of the reticulo-rumen of fistulated cows 14 hours after feeding and found there was little difference in the total amount of in- gesta when the dry matter intake, as alfalfa hay, ranged from 4.0 to 12.2 kg. per cow per day. There was likewise little difference in the percentage composition of the ingesta at different levels of intake with reapect to water and dry mat- ter. Similar relationships have been observed by Makela (1956) who sacrificed cows after feeding them timothy-clover hay for 10-15 days. The levels of dry matter intake ranged from 2.4 to 12.0 kg. daily per cow. The animals were always sacrificed at the same time of day after feeding and the amount of contents in each segment of the alimentary tract determined, as well as the quantity of dry matter. ROgerson (1958) fed sheep diets of widely different types, ranging from hay alone, through an intermediate diet of hay r5 2mm 1'. fl .'.».1 ”i for ‘ . "§~I‘v '0.“ ‘ L . "' in (“‘3 .M u. 1': (:1‘. "i a? u, o...v‘ “‘05.. ‘u' a 1,. a .iifgue D ‘n ? . , 4‘“. " ... e 1 :J 1 "; :-et“v ,.‘ 3 ..= "' \u : 4: F 0‘ . "4-.., 0., . .‘\ 2‘- U“ 'E: "s p 81 and cassava meal to a diet entirely of corn meal. Figures obtained for the amount of ingesta and the quantity of dry matter in the reticulo-rumen show marked similarities deepite the fact that the sheep fed hay and the sheep fed hay and cassava meal received considerably more dry matter daily than the sheep fed corn meal. Data presented by Balch (1958) sug— gest similar relationships existed for cows receiving a vari- ety of diets at different levels of intake. Nevens (1928) found, in comparing cows maintained on full feed with those fasted prior to sacrifice, that fasting had little influence upon the amount of contents in the reticulo- rumen. The ingesta of the animals subjected to fasting, how~ ever, clearly contained a lower percentage of dry matter. This finding is in good agreement with the results obtained in a number of other studies. Thus, from available evidence, it seems reasonable to assume the weight and dry matter percentage of ingesta in the reticulo-rumen at any given time varies only slightly, despite large variations in the level of feeding. 0n the other hand, it appears that rather substantial changes take place in the total contents of the reticulo-rumen as well as in the quan— tity of dry matter with time after feeding. Hale (1959) found the weight and dry matter were about one-half the amount initially present, when the contents were removed from the rumen 24 hours after feeding. Very similar results have been -.i t" 1' u- .159]: ‘.i'l§.'w r 2wtrue hl- I». NIH-.Q 2L1, noun-t... ,..e..§c a: I , A V l hue-uh. AU '_:'|: ":cdr‘ we..uub . '31 H» ,4 .. "'-',' K. {- x «n. .,. .- I 1. (p - I U.,e CA1:- 82 obtained by Gray gt gl. (1958a, 1958b) for sheep. Recent re- sults reported by Balch (1958) for cows corroborate these findings and, in addition, indicate the declines both in total contents and in amount of dry matter are linear. From the data presented by Balch (1958) and by Gray §£.§l- (1958a, 1958b) it might be concluded that the ingesta passing to the omasum progressively decreases in dry matter content as the time after feeding increases. According to Balch (1958) this is unlikely because of stratification in the rumen-and the tendency for the ingesta in the reticulum and anterior rumen to be always low in dry matter content. Furthermore, Balch found the ingesta lying in the region of the reticulo-omasal orifice showed very little change in dry matter content throughout the 24 hours except for a temporary rise imme- diately after eating had begun. As the dry matter of the ingesta accounts for only a small percentage (5—l5%) of the total weight, it is evident that changes in the amount of water present in the reticulo- rumen must be considerable. By catching the food boluses in a rubber bag as they arrived in the rumen of fistulated cows, Balch (1958) was able to calculate the amount of saliva pro- duced when different types of feed were eaten. For every 10 1b. of hay consumed 45-57 lb. of saliva were added during eating whereas only 12-15 1b. of saliva were added for every 10 1b. of concentrates. Thus, with many of the diets which V‘ .6 § .' filéuu LO ‘1: .1253": ‘5 r2 .i -"~ “:\‘I: O'F‘ .‘1 :“'::~" 95‘. .'"".-“" o a... ‘\ 52.3“ 4,”? “Min 8 N I u . ‘ - ”:45“ h ‘3‘ ~ U ' wJ “v 54 It. :,-": ‘ N'" I? vb“ “'1; . . ‘ 4“ ‘3 h u. .>‘.. 83 might be given to a cow more than 100 lb. of saliva would be produced merely during eating. This agrees well with the total daily production of 150 lb. or more of saliva proposed by McGilliard (1955) for the cow. In addition, it is not un- usual for a cow to drink 50 lb. or more of water per day. The extent to which water shifts between the blood and the rumen ingesta is not known. As a result of these additions it is obvious that the amount of water entering the rumen is rather appreciable. Again, the loss of water from the rumen via absorption and passage must also be appreciable. From data presented by Balch (1958) it can be calculated that the mean loss of water from the reticulo-rumen of three cows and two steers was 150 lb. per day. Sperber gt gt. (1953) calculated the outflow from the rumen through the reticulo-omasal orifice of acow by employing polyethylene glycol as a reference sub- stance. In a cow weighing 1200 lb. the loss of water was found to be in excess of 250 lb. per 24 hours. It was con- cluded by these workers that such a high outflow must be cor- related with a correspondingly high production of saliva. Using a method for quantitative collection of saliva Sperber gt gl. (1956) obtained good agreement between saliva produc- tion and estimated outflow from the rumen of the sheep. Al- though these estimates provide some information as to the changes that occur the precise quantities involved are diffi- cult to determine because the amount of liquid present merely isms"! D .-u"""" " . i...” ‘r; c h", «a ‘- t n ". ‘q':§ '- - was.-. “ ‘2 U '04 93:9 0:2 84 represents a balance between that entering in the drinking water, the saliva, and possibly from the blood, and that leav- ing via absorption or by passage to the omasum. In contrast, it can be assumed that the amount of dry matter leaving the reticulo-rumen each day is equivalent to the amount taken in, providing the animal has been maintained on a constant ration for a suitable period of time. Recent evidence obtained by Balch (1958) lends support to the valid— ity of this assumption. Balch found with cows that the mean loss of dry matter from the reticulo-rumen (by absorption and by passage to the omasum) during the day was 15.? 1b.; the mean dry matter intake per day for these same cows was 16.0 lbs. The loss of dry matter during eating appeared to be much more rapid than when the animals were not eating. A number of investigators have attempted to partition the losses from the rumen into those due to absorption and those due to passage through the reticulo-omasal orifice. Hale gt gt. (1947a, 1947b) have attempted to measure the rate and extent of digestion of the various components of alfalfa hay in the rumen of fistulated cows by analyzing the whole contents at the middle and end of the feeding cycle. They found approximately 50 percent of the dry matter was digested within 12 hours after feeding. Prolonging the digestion periods to 24 hours did not increase the rumen digestion co- efficients. It should be pointed out, however, that the values . . .c .' p ‘rw :..2..:ed .y u..- r’u‘n ‘. ”u"- ' :34 .411. low-cl ”v; '13!- I‘h 1 -lI-wN \V :":- '95“. r -. “u b w»¢.i.g . lr:4 :1 hn‘aflw Lu.) VLVJe¢V“ .‘:' ‘In R ‘ '--~ v: 8Y1”. up) i. ‘ . M ~---.:S‘.1'r as ”3"! “was “an; 1 toy J .7”. . i . N‘ ‘ teni'fl . CA I‘ , 4‘ “v. ‘M:=*e' ‘ uh “ I _. . . , ‘ ‘1“: P. - “Cy. a. ». ."W “'2. 9""- “.6 .'-.‘_ .‘ _ l"- .‘HJ‘S S ,. - a \._ 9* ‘1 \ “ ‘n« 4‘ .. ‘4 as.” ~ '5 .H e: ‘.. ‘>I . 02$ 85 obtained by this method are not, by strict definition, coeffi— cients of rumen digestion but are measures of total loss from the rumen (by passage and by absorption). Gray gt gt. (1958a) sacrificed sheep at various times after feeding and determined the extent of dry matter (air- dried, alcohol—precipitated solids) digestion in the reticulo- rumen by examining the dry matter-lignin ratios in the omasum or abomasum as well as in the rumen itself. The following rations were fed: 1) 500 g. wheaten hay and 250 g. wheat straw, 2) 800 g. wheaten hay, 3) 400 g. wheaten hay and 400 g. alfalfa hay, 4) 800 g. alfalfa hay. The concentration of lignin in the dry matter from the various compartments sug- gested that only well-digested material reached the omasum and abomasum from the reticulum even in the period immediately after eating. Coefficients of digestion for dry matter in the reticulo-rumen increased from about 55 percent for wheaten hay and straw to about 45 percent for wheaten hay, 53 percent for wheaten hay and alfalfa hay, and about 60 percent for alfalfa hay. These values were uncorrected for any dry mat- ter that entered the various compartments of the stomach from endogenous sources, for the solids that passed into the alco- holic filtrates during their preparation, and for the small differences in moisture content of the solids and forages. The diets used in these experiments consisted of relatively uniform material, and whether the ingesta of sheep fed on 1"- (I. -1 u_) u. . J ) I 3 my»; "rg‘ - “41-x. u. U u“ ‘1‘ fl"‘ .. .... VJ wJ—l‘: ‘\-- '9’; ”‘1'; o d - .... 5..., on I .._a J (I, l q ». |' I it .. .:A‘o;e of .:¢L“‘ ' A H' "4.4- ~ 9 A 'z': s ~ \0 c: -: -. 1"“! ”-_&. :‘a ‘ \._‘p " Y: “\ s‘ p: '.;5“2 '.-o-“‘ C ."‘ 'b‘h2'7“ “‘A.'r ‘ 2 \. Tgfi‘ 86 mixed diets containing materials of widely different dens- ities would behave in the same way is not known. One might presume that under such circumstances it would be more diffi- cult to collect samples representative of the ingesta passing from the rumen during an entire feeding cycle. By applying the lignin-ratio technique to combined samples of ingesta taken at frequent intervals in close proximity to the reticulo—omasal orifice of fistulated cows Balch (1957) determined rumen digestion coefficients for rations ranging from all hay to rations low in hay and high in concentrates. The range of apparent digestibility of dry matter in the reticulo-rumen was 26-62 percent. With diets containing large amounts of concentrates a larger proportion of total digestion tended to occur in the reticulo—rumen than with diets contain- ing predominantly hay or only hay. Again, the accuracy of these values as measures of the balance of outflow from the reticulo-rumen over the intake as food must depend entirely on obtaining a representative sample of the ingesta leaving the reticulo-rumen. Rogerson (1958) used a technique similar to that employed by Gray gt g1. (19583) to determine the extent of digestion in the rumen but sacrificed the animals at only one time (16 hours) after feeding. The diets given were of widely differ- ent types, ranging from 600 g. of Rhodes-grass hay, through an intermediate diet of 500 g. of Rhodes-grass hay and 300 g. of A...‘.§ 1p: nun-"b Lita ‘:Q:; vol 9% L... l’HawOncs: ‘ “lily. " .9 I u ‘ ' a .9 ‘ e ‘ L... C _Q ‘ J? n '1 87 ground cassava meal to a diet of 300 g. of corn meal. The results indicate that 40 percent of the dietary dry matter was digested in the rumen of the sheep on the hay diet com- pared with 50 percent on the mixed diet and 75 percent on the concentrate ration. The observed increase in digestibility in the rumen as the amount of concentrate in the diet increased is in agreement with the findings of Balch (1957). It is inter- esting to note that, despite differences between techniques and without taking into consideration differences between types or quantities of hay fed, the results obtained for the digesti- bility of dry matter in the rumen by Hale gt_gg. (1947a, 1947b), Gray gthl. (1958a, 1958b), Balch (1957) and Rogerson (1958) are quite similar. It is well known that ingesta in the omasum is consider- ably more dehydrated than that found in either the reticulo- rumen or the abomasum. This suggests an intensive absorption of water from the omasum or the preferential passage of the more liquid ingesta on to the abomasum although neither mech- anism necessarily excludes the other. Benzie and Phillipson (1957) interpret their radiological findings as being more compatible with the latter theory. The change in diaposition of the omasum, which they noted when the reticulum contracts, suggests that the organ forms a receptacle at this time so that the reticular contents entering it would tend to run into the interlaminar spaces. Upon contraction and return of . 'vn Ali, 0 v I ‘ 9 but "L“‘ 13., £00 nar"c“ '4HL. -¢- 0 $ -::: straw u - I 4 h." vi": Pf 5T . 1..“ J " 1;“ A\:‘ r“ H .~\.\-U.C . | ‘ ‘Q In k. n‘ ‘N: 0' I ~Igiuu u any! Na‘ \. . -._.&.'3-‘, b l .‘I : ~C.‘A"A ""1 Védu‘: ’V"!, I - A -....:t 2"" .aa.‘ 88 the organ to its upright position much of the liquid may then flow ventrally into the abomasum leaving the more solid in- gesta entrapped between the laminae. In contrast, the observa- tions of Gray :13. 5;. (1954) indicate that negligible amounts of reticular contents pass directly to the abomasum through the sulcus and that little, if any, liquid is squeezed away mechanically from the solids in the omasum. More recent in- vestigations, in which movement of the ingesta between the laminae and through the omasum was followed, suggest that both mechanisms are Operative (Badawy 23 a;., 19588). Direct measurements of the extent of absorption from the omasum are difficult to make, hence most values have been estimated indirectly. Both Bouckaert and Oyaert (1954) and Boat (1957) have described methods for collecting ingesta directly from the intact omasum but, as yet, no detailed accounts of their use are available. Raynaud and Bost (1957) ligated the omasum, excluding the blood supply, of five anesthetized sheep and one anesthetized goat. By perfusing the omasum with an aqueous solution of polyethylene glycol it was calculated that an average of 1.4 liters of water was absorbed per day.. This value represented about 58 percent of the water introduced during the perfusion process. Raynaud and Boat considered the value to be low in comparison to that for unanesthetized animals and postulated that absorption is of the same order of magnitude as salivary secretion. It is uni-H r n‘n‘ I“: MON '.5- uln. 3‘ ' i: ’.:‘ 3. tr .7 I'm: 5“”5“ 'n ~~¢V “Lu... 1";chI’ n.c.u‘..le g‘z‘ . O I H ..1 .0'} t‘-... R, we“. a; it: I . 'n V I n. ‘:-‘. a . .._ :q -‘A.‘ ‘|_'I ,. . u,- ‘hAA‘ ./ 5...:r! "LU: .. n.- .'"J.. 9 9 'n {f a L ' 89 questionable whether this figure is absolutely valid however, in view of the fact that passage through the organ was static. On the other hand, the figure does serve to illustrate that intensive absorption can occur in the omasum. In two groups of sheep studied by Badawy gt al. (1958) the amount of water lost in the omasum was found to be 48 and 55 percent. Both figures are within the range (53—64 percent) found by Gray gt gl. (1954), but they are slightly higher than the figure of 43 percent calculated by Boyne gt El. (1956) and by Rogerson (1958). According to Badawy _e__i_:_ 3;, (1958) these losses in water are due, only in part, to ab- sorption. Losses of dry matter in the omasum are due primarily to the absorption of the soluble products resulting from fer- mentation in the rumen, i.g., volatile fatty acids and NH3, and of soluble ash. The absorption of these substances will be discussed in subsequent sections. It is well known that omasal ingesta is diluted to some extent by the secretion of gastric Juice in the abomasum. Sperber §£.§l- (1956) found, by maintaining the concentration of polyethylene glycol constant in the rumen, that its concen- tration in the abomasum reached about the same level. This suggests the absorption of water in the omasum is approximately equal to the volume of gastric Juice added in the abomasum. By assuming gastric Juice is not stronger than 0.1 N HCl, “mtg“ 9": ””5,‘ .n . A I IQ u‘vn hi . z'.'co\1 {ti-v ..lI‘f. w I.":“(I-. 0 «Win: in. «ML..‘ .. g - 1 "1‘ ‘1” ‘i “ tax.“ (I "II-=5; b, a nu.“.~ weex. ll. 1.“:“ D “I "J‘A‘.\. "’Q'JpQ.‘ 0' « _ "" Uv‘ nu!‘ tr; :. ""‘i any n in» N u ,0"; "" ‘v' _ «.5: 3'3“; " 4“ _ v ..~ 'I, u. .‘ -P{‘,“ ....““ . .. I ‘3‘ I"... : qu- 1‘ ‘H.\ 4., '-.5 ‘rfi‘ ‘ 1 a't‘l .. . . ‘ “at ‘-. i... '\ ,“~ .. m: 1. _ .5. 90 Sperber and his associates estimated that 1.5 to 2 parts of gastric Juice are needed to acidify 1 part of rumen or omasum contents. This ratio is similar to that proposed by Vasson and Phillipson (1952) who calculated that 9 parts of gastric Juice would need to be added to 1 part of omasal contents to produce the chloride concentration present in the abomasum. From studies with two groups of sheep Badawy gt gt. (1958) calculated that 1.? and 1.9 parts of water would be needed to bring the dry matter percentage of the omasal contents down to the level existing in the abomasum. Solids of the gastric Juice were not considered. The amount of ingesta passing from the abomasum of a sheep consuming 1200 g. of hay per day has been estimated by Phillipson (1952) to be 9.6 liters (4.9% dry matter - Nasson and Phillipson, 1952). Similar results have been reported by Hogan (1957) who calculated that 4300 ml. of water and ass a. of dry matter passed to the lower gut in 19 hours. These values indicate that about 5 liters of water were added to the ingesta in the stomach and that 70 percent of the digestible dry matter of the ration was lost between the mouth and duo- denum. The additional water was presumed to have come from the saliva and gastric Juice. Scerbakov (1958) calculated that an average of 170 liters (4.6% dry matter) of chyme passed through the duodenum daily of two cows receiving a mixed diet of clover and timothy hay, bran, barley meal and 91 oil cake. It is interesting to note this figure is of the same magnitude as that reported by Sperber gt gt. (1956) for the outflow of ingesta from the reticulo-rumen of a cow. It is generally agreed that little, if any, absorption occurs from the abomasum. In fact, a number of studies indi- cate that the dry matter increases to some extent in this organ due to the addition of nitrogen (Hogan, 1957; Rogerson, 1958) and soluble ash (Boyne gt_gl., 1956; Badawy t al., 1958; Rogerson, 1958). The nature and extent of these addi- tions are not entirely clear. Available evidence indicates there is a substantial addi- tion of dry matter to the ingesta in the proximal duodenum. Boyne gt gl. (1956) found a considerable increase of nitro- genous material in this segment of the intestine of sacrificed sheep and from preliminary investigations of the combined bile and pancreatic secretions concluded that the nitrogen was derived, only in part, from these secretions. Subsequent studies by Badawy gt gt. (1958) and by Rogerson (1958) have confirmed this addition of nitrOgenous material in the proximal duodenum of sacrificed sheep. It is of interest, however, that this marked rise in nitrOgen was not found by Badawy and others in living sheep fitted with permanent cannulas, or with an exteriorized flow of the small intestine when the cannulas were located relatively near the pylorus; neither was it ob- served to any great extent in the duodenum of sheep under anesthesia. Histologic studies of the mucosa indicated that u- I -" .fl . a - . "v' n... I. Ix. ' u ‘| A ‘ e0 '5; ‘. -‘ “‘v a N. h.. v ‘ vi ‘:‘-~.‘ g i. ":I b. ' ..' 3:, ,r: II‘O". y.“ . ‘ 16‘ . .- 2 a ’- -.l¢-.. v. y.. . . ‘ I'm.‘\ a...“ h “'-‘§ ~-- t,._ ”n ..-_ J. 5K.“ I . Nye :I61_.1 ‘ "“I§o.“ . L): Ti 92 shedding of the epithelium was extensive in sheep which had been sacrificed for examination. In addition to an increase in nitrogenous material, Rogerson (1958) observed considerable additions of ether ex- tract and nitrogen-free extract and consequently, of dry mat- ter to the ingesta in the proximal part of the duodenum. By the time the cecum was reached, however, absorption of almost all of the digestible nutrients had taken place. Hogan (1957) found that about 11 percent of the digestible dry matter was removed between the duodenum and cecum and about 19 percent between the cecum and anus of sheep fitted with a re-entrant fistula either in the first part of the duodenum or in the terminal part of the ileum. These values fall within the range of those reported by Balch (1957) for the digestibility of dry matter (12-54%) in the hind gut (omasum, abomasum and intestinal tract) of cows. Dry matter losses in the colon appear to be negligible, with the notable exception of sig- nificant amounts of soluble ash (Boyne gt gt., 1956; Rogerson, 1958). Some degree of dehydration takes place during the passage of the ingesta from the pylorus to the cecum, but the bulk of the water appears to be removed from the ingesta during its passage through the terminal section of the colon (Boyne .23 g;,, 1956; Rogerson, 1958). Hogan (1957) found that about 4&3 percent of the water in the ingesta which entered the small ,,o,.olp a '- ”..-uguv V J ‘ ':- m: .....v.v A “:i;~"m e .. .xva ..' ' 9 \ I '1 noun-nut '-au .5... ———__. . I P ‘r— 'n.._. .|‘ O _ ‘ ’i‘ A" a"... 01 an r. , ... - a '5‘. c v _.“ s: ‘4‘. Q" , " -u-: 95 intestine of sheep was absorbed by the time it reached the ileo-cecal Junction; about 93 percent of the water entering the cecum and colon was absorbed. The carbohydrate constituents In the conventional feedstuff analysis, carbohydrates are found in the crude fiber and nitrogen-free extract frac- tions. Nitrogen—free extract is determined by difference. Neither of the fractions represent discrete chemical entities, but are highly complex, consisting of varying prOportions of the celluloses, hemicelluloses, starches, soluble sugars, pectic substances and lignins. Nordfeldt _e_t g_l_. (1949) and Hansen gt gt. (1958) have reviewed much of the literature pertinent to this subJect. A comprehensive compilation of data relative to the composition of cereal grains and forages has been prepared by Miller (1958). Undoubtedly the most useful and unique feature of rumi- nants is their ability to utilize complex carbohydrates, due not to the enzymes secreted by the animals but to fermentation in the reticulo-rumen by micro—organisms. It is well estab- lished that soluble sugars in the diet are fermented to give short-chain fatty acids and that this is the terminal stage of carbohydrate breakdown. Much less is known about the primary stages of cleavage of the more complex constituents, cellulose, hemicellulose, etc. into soluble products. The . «was ”we ..‘“; u". .L n ‘~:r‘~' two A? “'n V it cant DwilcrOc “0" \I'v‘ u on H ex 0.. .3" 9’ ..‘ _ -\.l,.§. - I V e ‘n- '1""":‘ “a V" -o:-... v. . .13 “9‘8: ' u-..», I '"qu . '."n ” Any. 9 I 2'“c‘f‘ O. I '5 5.0.. \u tut o l V - 7v $ . fin . , P: , bn.. 94 general types of transformation that occur in carbohydrate digestion are schematically illustrated in Figure 1. Of the various carbohydrate constituents consumed by ruminants cellulose is undoubtedly the most important quanti- tatively. It is the principal cell wall constituent of all the higher plants that have been investigated and accounts for some 50 percent of the dry matter of many of the commonly fed forages. _ Tappeiner (1884) appears to be the first to show experi- mentally that the disappearance of cellulose in the alimentary tract is the result of fermentation by micro-organisms in- habiting the tract. Some years later Pringsheim (191?) demon- strated the production of cellobiose from the hydrolysis of cellulose and postulated the existence of two enzyme systems, cellulase and cellobiase, the former producing cellbiose from cellulose and the latter hydrolyzing this disaccharide to glucose. By using toluene he was able to inhibit the growth of the micro-organisms in a thermophilic fermentation with a resultant accumulation of reducing substances. These were identified as cellobiose and glucose. Similar observations ‘were subsequently reported by Woodman and Stewart (1928). Antoniani (1935) could find no evidence of cellobiase in the mucosa of the rumen, yet the presence of this enzyme was readily demonstrated in the expressed fluid. He concluded Ifllat cellobiase was primarily of bacterial origin. Hydrolysis 95 Figure 1. Pathway of carbohydrate constituents alimentary tract in the 't ‘- 6 96 DIETARY CAR BOHYDRATE Cellulose Starch Lignin Hemiceilulose (Soluble sugars / Pectic materials Plant ocids Hexosons, pentosons RETICULO-RUMEN AND CMASUM r . t l. \ {/7 MlCl’OblOl -~ / / + «.1 \CO . polysocghgides \\ , 2 /' \.\ , lg / + /’ f i \\ ‘ '\ ‘ . xShort chain ./ f \» Loctote _.__._-._ .- Absorbed os fatty acids ,3/ ; (succinote) l ..' such or as i f f l' propionic dCid \ l l Endogenous , ..’ \ \ i, ; microbiol / / ,1" \\ l l metabolism X \_ \ l 2 ‘ N-free* l \ compounds; \ \-~’——/ ABOMASUM Dietary l carbohydrate‘ ' l l. i l Microbial . carbohydrate l l y l t ' Hexoses ; DUODENUM + l Carbohydrate) resipues j +— Intestinal enzymes—«r- ..x. From deomino tion of l' amino acids l v ‘Q . ‘ ‘l:e;.u1:>se we Q '7 rs ‘1'. " I mo c. ..‘—r.‘ 'Eiiii :ellulos 39113 9c“: ] .ayy 9|. 0‘, 0 ”:n‘ 0'. “4e .er lye; ttmei 913 1 up ‘ ...x-._A m -.. l :“‘r‘ .i..:.,.ve, Cerf ‘. ‘ e .‘ a...». 1'5 ‘1'” l. . is..." “,5 '2'Stfi‘ 'n I -. ‘L“ \ 4 3" Var“ I. (..‘..‘r ",:-l ‘- . y’: ..‘“ c EC ‘ z 1‘ “ g ‘ e an. rev H$ 5"‘5‘ ‘ "Kile ‘:I‘| 97 of cellulose was Optimal at pH 5.0 which is somewhat below the normal pH of the rumen. Pochon (1935, 1958) isolated a cellulose-splitting organism from the rumen of the ox; it far- mented cellulose with the production of a mixture of lower fatty acids. If the pH of the medium was reduced to 4.0 dur- ing the fermentation, glucose accumulated. Glucosazone was prepared and identified, and a second crystalline osazone was assumed, but without proof, to be cellobiosazone. Further evidence, confirming the production of cellobiose and glucose as intermediates from cellulose by organisms isolated from the rumen, has been reported by Hungate (1944, 1947, 1950), Sijpesteijn (1949), Kitts and Underkofler (1954), Wang (1956), Gill and King (1957), Halliwell (1957a, 1957b), Festenstein (1958) and Stanley_and Kesler (1959). Succinic acid is a major.intermediate of a number of cellulose-decomposing bacteria isolated in pure culture from the rumen. Sijpesteijn (1951) isolated an organism from the rumen of sheep and cattle and found that some 25 percent of the carbon of cellulose or cellobiose could be recovered as succinic acid. An actively cellulolytic organism, isolated from the bovine rumen and described by Hungate (1950), was observed by Sijpesteijn and Elsden (1952) to produce 51.3 mg. of succinic acid from 82 mg. of cellulose. Bryant and Doetsch (1954) isolated a number of strains of bacteria from the bovine rumen, all of which produced large amounts of succinic 2:::' fm cellt fr: :mioclc "OD. q . .- l 039:" U at“, \. .‘L . Fr? mi: yr. " ‘5‘? no? --‘ a-) .ru . Il...l ! . '95 O ”I‘“"‘ Am" i 3‘.‘_ H «1., “ere 93‘ ‘~ 0 in: “ . . W .. f‘ ac ~18 E ; ‘ 'lfp‘ . :IYF‘“ "I v- i .ra..‘ ~39 A . ‘ 1..!:.l (‘3 :\ ‘v Ll ‘:'.‘l "_‘I‘ Tfi c I‘F .‘on b'v J ‘:‘l 'v“3‘ N‘,‘ y” .4.7.P31 \x‘. ‘ I .~~ I “~339 w -r,‘ “"3 \ ‘2‘, i""‘:‘.'\ V‘\ H ._ ‘4 ':- I'l- .~ -. \ .Ei ‘ 1‘“ 98 acid from cellulose. The decarboxylation of succinic acid to form propionic acid has been studied by Hungate (1950), Johns (1951), Doetsch gt al- (1955) and Sirotnak at al. (1954). From available evidence it would appear that there are at least three distinct stages in cellulose cleavage. Ini- tially cellulose is broken down into smaller fragments which may or may not be soluble. A number of investigators have obtained from rumen micro-organisms cellulolytic extracts which were active on degraded or cellulose derivatives but were practically inactive on undegraded or native cellulose. Recent examples of such preparations have been reviewed by Halliwell (1957a). Deepite the feeble action of these ex- tracts, the required enzymes must certainly be present in the parent rumen organisms, for no matter what form of cellu- lose is presented to them, complete cellulolysis usually takes place. Halliwell (1957b) and Gill and King (1957) attribute this to the presence of a multiple enzyme system containing at least two enzymes, the first of which attacks more complex and insoluble molecules and thus renders them sensitive to degradation by a.further enzyme. Hence, truly cellulolytic micro-organisms containing the two or more enzymes are cap- able of hydrolyzing native cellulose as well as degraded cellulose and the soluble cellulose derivatives. On the other hand non-cellulolytic organisms lack this primary enzyme and, as a result, fail to attack insoluble cellulose, although s:'.::.e 29-2.2 Q Iltl‘ A ' "' :f O. VEOXI u l'cfi‘"."" D run-“m- l .c 9- .‘.y I ‘RO ‘ "..'“:V SS, "'1! ' ‘ fl‘a ' "t... \u NF a._ b ,.. ..., J, “‘R‘ ‘ “ 93:: " "v , u -b" u "a. ‘F ..‘. 9., V -" “31° F; ' u :‘iflu I: ..' - "- iusan ‘ ' ye. . ‘1’.“ u ' an ..N 5 I. N ., . Ir) ..a. l I: (D '1) CD A 'I g ‘ '3: at. N ..‘. u a "v- ’\ . ‘5;"(l s‘v \i . "a . . ‘I . ‘2. -‘ a ‘ I “‘s‘:“‘ - - 1- UL )u In .'l.:\‘ ..‘IV‘AP 3"“ 9 ‘ IQ I! \,‘l. 't...r{ u "““i :".r\ \*: ‘\ ‘l 1'." 'N ~ 9 in 3, .i, “Q l‘ t .‘..‘ ‘5‘ '~ “m '\ "l x- y“ \.‘ .. - l \' :“‘ 99 soluble cellulose derivatives are often readily hydrolyzed. It would appear then, that in dealing with degraded cellulose derivatives as substrates, we are dealing with the second phase of cellulose cleavage. The nature of the initial action on insoluble cellulose still remains uncertain. After the initial depolymerization of cellulose an enzyme, like amylase but acting on fi-instead of a-glucoside linkages, takes the breakdown to the oligo-saccharide and cellobiose stage. Recent evidence indicates the depolymerized cellulose chain is split in a random manner, for cellopentaose and possibly other anhydro-glucose polymers, as well as cello- biose, have been detected as intermediates of cellulose degra- dation (Hash and King, 1954; Wang, 1956). Conchie (1954) prepared a B-glucosidase from sheep rumen liquor and studied the kinetics of its activity by using o-nitrophenyl fi- glucoside as a substrate. Its property toward cellulose, how- ever, was not studied. Finally cellobiase hydrolyzes these intermediates to glucose which is rapidly fermented to the lower fatty acids. The formation of glucose as a major transient product in the digestion of cellulose has been repeatedly demonstrated. Antoniani (1955) observed cellobiase activity in rumen liquid but was of the opinion that it was not exclusively of bac- terial origin, part of it at least being derived from vege- table sources. The recent investigations of Festenstein ‘33‘ in 'I'V" i .6 ..ov. . L it‘ll I .’ :ocr‘ p". 5:: a; "twe- ‘ O r ’gnngr I V. x h v-A a --P‘. \ d‘ R‘ .. . \ «VH‘V', .-n o'.‘ ‘ ‘ N.‘ :p,‘ h l “‘r‘ "‘ l. ‘ .o- \.c ‘ 2‘2““ ‘1. ‘. ”z“... ..‘,g‘ct: “ \' ..‘ Ti; ‘ ' s v» “.I L’a ..' '5‘ ‘ t .‘ ‘ I‘ls ‘ V" ‘ “‘1 C‘ ‘. ..‘ . .‘- _~‘_‘~ ”a ‘- 1 "c a 100 (1958), in which gluconolactone was employed as an inhibitor, and of Stanley and Kesler (1959), in which glucose was added to the fermentation media, lend confirmation to the presence of this enzyme in rumen liquid. The terminal stage of cellulose breakdown has received considerably more attention than the various intermediary stages of decomposition. Elsden (1945) studied the fermenta- tion of cellulose both lg gilg and £3 31339. Cellulose pulp was employed as substrate in the lg giggg studies; dried grass was used i3 Ellg- The fatty acids produced from the i3 gipgg decomposition of cellulose were only qualitatively similar to those observed in the rumen liquor. Quantitatively acetic acid predominated ig_yigg, whereas propionic acid was present in the largest amounts gg Zlfigg. Similar results for ig_yit§g determinations have been reported by xerston (1948), Gray gt fig. (1951b), Gray and Pilgrim (1952), Herschberger g; 3;. (1956) and Barnett and Reid (1957). These results suggest that if fermentation in the rumen is confined strictly to cellulose then there should be a preponderance of propionic acid in the rumen. This point has never been conclusively proved or disproved for, under i__1;zg_conditions, the exact nature of the fermentation has always been complicated by the presence of carbohydrates other than cellulose and by the dif- ferential rates of absorption of the various fatty acids. The cellulose—splitting bacteria are notoriously difficult fibikte in l-A..‘ .2: h:ve be '.- . l lr 3:53-91“? ‘" I 0":' A11 .L‘ .L.--' :‘r' l‘ac 9' F .u... my-) on“ . . O ‘ I-u‘ «an A. . c L“ i‘vlitifl . T,“ o .xsnen. revis ~1m5’13::l '4“: \$~val l.“ A 8‘ W " " t,” .m" VS‘QCL‘ “filial Nu"! ' ~ “Mai“: 081‘ PM. II..' o + .- u s . ._“. LF‘VHY Sc- y.- . :w W lull Qirzl A“ J“~“4t" \«‘ (i 5‘ ,, ‘ “ “ CPD 6 I i. It . '. g,“ ‘-. o ‘ ' .;3 ‘cu‘: ‘ n}: . ‘~ '6» Its... jar, ,, . \l ‘ '~" thi- " - Whfi s . (“‘7 L91 K it ._ at ad» ”O‘VH b"‘l4 3' v s ‘_. I we ij‘H?‘ I" In" A ..‘ y “HIV“: '1 "*485 . ‘4‘- ‘ try-ca / ..- , A "' 14:9 V J ..'..n t. 101 to isolate in pure culture but Hungate (1950) and Sijpesteijn (1948) have been able to study the fermentation of cellulose by bacteria ig zitgg under conditions similar to those in the rumen. All thus far have been anaerobes or facultative anaerobes, and their fermentation products have included short-chain fatty acids, carbon dioxide, methane and hydrogen. Excellent reviews concerning the production and origin of the various rumen gases have been written by Cole gt al. (1945), Edwards (1955) and Kleiber (1956) and will not be discussed here. Available evidence indicates that the coccoid forms are principally reaponsible for the disintegration of plant tissues containing cellulose though there is considerable pleomorphism shown by these organisms (Baker and Harries, 1947). Short- chain fatty acids are the principal end products of their activity. Considerably more speculation exists with regard to the role of protozoa in the degradation of cellulose in the rumen. The early studies by Becker 23 £1. (1930) and Becker (195a), in which defaunated animals used cellulose as effectively as the faunated controls, suggested that the protozoa did not digest cellulose. The possibility that cellulolytic bacteria in the defaunated rumen assumed the entire burden of cellu- lolysis was not eliminated. Later cultural investigations by iHungate (1942, 1945) indicated that certain rumen protozoa grew'well in media containing cellulose but failed to grow if .,, nai’ulgse w I." V"“ .‘.. fl 9 9 +1- en h: Jnjbjzg -' h“ u.” I,‘ :luollbs ”2.5 no ..‘" v " intiwi by 2:11 a. 0 9 l 'l at“: 1* (10.; ”$4 gresezze of the‘ J 'I‘ “'l t ‘.' ..l :29 Ill-lane » ‘ l . a . 1.7533 C4 he .._, 102 the cellulose was omitted. Whether cellulolysis was due to the protozoa themselves or to their intracellular bacterial symbionts was not definitely established. Recent evidence obtained by Halliwell (1957) suggests that rumen protozoa owe much, if not all, of their cellulolytic activity to the presence of their associated bacterial commensals. Quantitative measures of the extent of cellulose diges- tion in the rumen are limited. Hale £3 3;. (1947b) estimated the rate and extent of digestion of the cellulose of alfalfa hay in the rumen of the cow by analyzing the total contents at 6, l2 and 24 hours after feeding. Cellulose was only slightly digested (12.8%) during the first six hours but was rapidly disintegrated (50.8%) during the subsequent six hours. No further digestion of cellulose was observed in the rumen after 12 hours. An additional 11.6 percent of the cellulose was digested in the lower gut (omasum, abomasum and intestinal tract). It was presumed this breakdown occurred primarily in the cecum. Studies by Gray (1947) indicated that the extent of digestion of cellulose in the rumen of sheep given a mix~ ture of alfalfa hay and wheat straw was about 40 percent. This work included examination of the cellulosetlignin ratios in the omasum and abomasum, but the results were limited in regard to the time after feeding.. More recently Gray gt g;. (1958) determined digestion coefficients for cellulose in the stomach compartments of sheep fed on four different roughage 3.531355 iii sc .16 l 39:15 trim 1 \ whi- FA ah LIL .DAL‘ 75/3 “ u "my. .. 'J ’L‘l: 095* VD, 1"" ii “a AM it _ "O~-o . 1' ‘95 ’32:: 30 . “'0',‘ f ‘ a. "he 0‘ ,.,, . ‘I‘s i ". "n at)! R * u . t K .Jh ‘u I 103 rations and sacrificed at different times after feeding. The results indicate that only well digested material reached the omasum and abomasum even immediately after feeding. In view of this fact, Gray g3 g1. did not consider their results, which were drawn from a series of experimental animals, to be suitable for the same sort of calculation used by Hale and others to determine the rates of attack on cellulose in the rumen. However, the extent of cellulose digestion in the rumen of sheep fed on a mixture of wheaten hay and wheat straw was about 30 percent, on wheaten hay about 40 percent, on a mixture of wheaten hay and alfalfa hay about 50 percent and on alfalfa hay about 60 percent. Some 16 to 20 percent of the dry matter of grass and hay are in the form of pentosans of which the chief component is xylan (Fraps, 1930; Ekelund, 1949; Hansen gt £l-. 1958) and are digested to the extent of about 50 percent in the ali- mentary tract of the ruminant. Marshall (1949) estimated that some 50 to 40 percent of the furfural-yielding components of meadow hay disappeared in the reticulo-rumen and omasum of sheep. Similar results have been obtained by Heald (1955) using sheep fitted with both rumen and duodenal fistulas. Gray _e__§ _a__1_. (1958) computed coefficients of digestion for the reticulo-rumen ranging from 25 to 60 percent for the pentosans ~of various hays and hay mixtures fed to sheep and noted that the digestibility of the pentosans closely followed the 51:25:11:th l. l 41230-01" 'iii“ia r t. oA-ILU ‘u ;:r‘.=:.:e of 'V \‘ I ) \ 3. ‘-.A‘ *1 ‘l‘! v '; V slid _ v-) ." .‘- “.ja ‘ ‘I' ”-9 at" 104 digestibility of the celluloses. Although pentosan—decompos- ing micro-organisms are widespread in nature there appears to be little information concerning the types and numbers of similar organisms in the ruminant, or of the quantitative im- portance of the fermentation of these substances. Howard (1955) found that wheat-flour pentosan was rapidly hydrolyzed by a snapension of bacteria from the rumen of sheep, and that under some circumstances oligosaccharides, intermediates in the breakdown, could be detected. No activity was detectable in rumen liquid which had been freed from bacteria. Sdrenson (1957) and Pazur £3 £1. (1957) independently have observed considerable xylanase activity in rumen fluid from cattle. Xylo—oligosaccharides were the primary intermediates; the reaction products after complete hydrolysis were xylobiase, xylose, arabinose and glucurbnic acid. These components are rapidly fermented by rumen micro-organisms with the formation of the volatile fatty acids, acetic, propionic and butyric acids, with acetic acid predominating (Heald, 1952a). Con- firmative evidence of this has been presented by Pazur gt g1. (1958) who found that washed cell suspensions of rumen bacteria broke down xylose-l-Cl4 and xylose-2-C14 to 014-1abe1ed acetic, propionic and butyric acids. Heald (1952b) further observed that the fermentation of pentoses by mixed rumen bacteria did not follow the same pathway as that followed in the fermenta- tion of glucose, a fact substantiated by Howard (1955). 0 “.0“; MW . g: H": " ._, r .319 “L... In (- u' ‘ ‘V -;H" ‘ .v‘ . “. ..‘: t ' 7 "’ 'J '3- u?- . .. o“\ ‘C I? ' "311 ‘- ’- I ‘5, “A! \tvo ‘ . I: ~ -~ ,b'n ~‘e ‘1 ’Y‘ »\..2 ‘L- ‘ B. .‘. , P 105 Although the amount of pectic substances in forages is usually small, between 1.0 and 1.5 percent, considerably higher levels of total pectin have been reported for alfalfa (10.4 percent) by Lagowski at 91° (1958). Leroy and Nichaux (1949) observed that sheep digested a high proportion of the "pectic substances" included in such feeds as applepomace, sugar beet pulp, hay and straw. Sheep feeding on hay consumed from 75 to 102 g. of pectic substances daily (Michaux, 1950). The proportion of pectic acid to pectin is high in apple and sugar beet pulp, however, pectin predominates in hay. Michaux (1951) found that the digestibility of pectic substances in sheep was approximately 75 percent or more for hay and 90 per- cent for sugar beet pulp. Digestibility was considerably less in a lamb. Lignin is not carbohydrate in nature but is included in the carbohydrate fraction by reason of association. It is a high molecular weight condensation product of one or more types of aromatic compounds intermixed in the cell wall with cellulose and other constituents. Roughages may contain from 2 to 3 percent up to about 20 percent depending upon the stage of maturity. Many investigations indicate that lignin is not appreciably digested by either cows or sheep and as a result it has been widely used as an indigestible reference for studying the fate of digestible constituents of the feed. On the other hand a considerable number of studies show relatively C “a? is ' 'n; I“ V ‘ ‘ “on. A 5'. “’ «‘an ocbvi or» If. “‘7lei3mus f . " 5‘..." fie r“ I * ml ‘1 . “_ ~ w \$. n u i:“c“ .I” h -‘-5 and “‘1 H AMP} ‘ .‘ .Q a.“‘) “3’n “A“ :5“ ~.-;' ‘an I“ W, ”A“ ““1 abs Hf. 35:” “..‘ Is “~.':‘ (“1% ~ ‘\.I’“;: ‘ 106 high total coefficients of digestion for lignin. Most of the available evidence indicates that the digestibility of lignin in the rumen is negligible and suggests that any digestion which does occur takes place posterior to this part of the tract. Several factors seem to partially eXplain these dif- ferences. Pigden and Stone (1952) found the lignin in di- cotyledonous forages was relatively unchanged by passage through the ruminant While that in monocotyledonous hays was partially digested. Salo (1958) observed that more lignin was digested from hay cut at an early stage of maturity than from the same hay cut at maturity. These findings suggest that considerable differences occur in lignin composition not only between forages but also within forages at various stages of maturity. Salo (1957a, 1957b, 1958) further indicated that different digestibility coefficients for lignin could be ob- tained for the same forage depending upon the method of analysis used. Starch is the primary reserve carbohydrate of most plants and, as such, becomes quantitatively important in rations containing appreciable amounts of grain. On the other hand, forages contain only limited amounts of starch. In both cattle and sheep microbial fermentation of starch readily occurs in the reticulo-rumen. Balch 33 gl. (1955) have estimated that 95-98 percent of the starch in a ration consisting primarily of flaked corn was digested in the g“:u‘o.r-Vnpr ..'-ed. i.‘¢u nu. all u a . p a» 9'4 .pc‘ 1'”! ;:;w;“n9p, .‘ ~ .‘ nt- i..." _ . saws “we: 'vl «Af,g ' n rater 32' 163 a” . a i ‘ an n ..‘. .r‘“9: U- «H ‘ . ~33! C.’ 17.3 I 335: a: .1 { --‘. ‘ L“:' ‘ '. no‘ t ‘\ 'u'} o‘. L. H‘ “23 la- ‘ " IJK" ‘VDVK‘ J l "n. .u 3 1? "I I U n t.' : u ’*5‘ l. .1 _ ,- ’ 53:. s‘ g h i J‘Ju‘ U ‘:.' ‘ .‘ y“a n‘ as N I :1 i :a‘ "1 “I“ 107 reticulo-rumen of cows. Similar values have been reported by Weller and Gray (1954) for sheep which received wheaten hay plus dehydrated potato chips as a source of starch. That which escapes digestion by the micro-organisms is apparently to a greater or lesser extent degradated by the amylolytic enzymes of the intestinal tract in accordance to the accessibility of attack on the starch granule. In studies with sheep and cattle Baker §§_gl. (1950) observed that little corn starch reached the ileum whereas potato starch was detected in the ileum and cecum after 4 hours. The partially disintegrated granules which reached the cecum did not appear to undergo any further change and showed few adherent bacteria. Numerous studies have disclosed a wide variety of starch- Splitting rumen organisms, including several cellulolytic strains (Hungate, 1950; Sijpesteijn, 1948), and various non- cellulolytic bacteria (Gall gt gl., 1947; Van der Wath, 194B; Gall and Huhtanen, 1951; Hungate at g1., 1952; Huhtanen and Gall, 1953; Bryant and Burkey, 1955a, 1955b; Jayko, 1953; Macpherson, 1955; Wilson and Briggs, 1954; Wilson and Briggs, 1955; Perry gt gl., 1955; Robson and Mann, 1955; Hamlin and Hungate, 1956; Briggs, 1956; Hungate, 1957) as well as pro- tozoa of the genera Entodinium, Diplodinium and Isotricha (Oxford, 1955; Hungate, 1955). Streptococcus bovis, Lance— field's Group D, appears to be the chief rumen bacterium con- cerned with starch fermentation and has been more intensively studied than any other rumen bacterium. Macpherson (1953), ‘* ‘ '0‘. ..‘”??? L b. 1:1...vv {I'D It) ( ) “II .H‘ . “1“ ..‘. C. K I p a“ fwd - ‘4' .v_ "“"M. .__"‘ .‘nt .. z \~‘ 8 . . 3. ‘-, “..‘. . q ‘. ‘ . t“ A“ ‘*.". .3:‘ .~ ‘ I 3,. ~\ . ~\ " .‘Q '~ . ‘Q - l‘ ‘.,u .. A : "J‘s 108 Higgenbottom and Wheater (1954), Briggs (1956) and Hungate (1957) have isolated numerous strains of S. pglis from sheep and cattle rumens (even when the animals were fed low-starch rations) by using standard bacteriological media. An atypical variety of S. pggis has been isolated from the rumen of the calf by Mann and Oxford (1955). Masson (1950, 1951) observed large numbers of Clostridium butyricum in the rumen of a sheep fed a ration rich in flaked corn but coccoid forms, whose chemical properties were similar to S. bovis, were also present and, as far as could be judged by the high concentration of lactic acid formed, were numer— ically significant. 9;. butyricum is known to produce an amylase in 11122 (Whelan and Near, 1951; Hobson and Macpherson, 1952), and a free amylase that occurs in the rumen of starch- fed sheep is presumably of bacterial origin, as no amylase is present in the saliva of sheep (Near, 1950). Similarly an amylase which hydrolyzes starch as far as the dextrin stage is produced in m by starch-Splitting cocci (Hobson and Manherson, 1952). Appleby (1955) found that Bacillus lichen— iformis, a proteolytic organism occurring in moderate numbers in the rumen of sheep, is also powerfully amylolytic. It has been known for some time that protozoa avidly ingest starch. According to Hungate (1955) and Oxford (1955) both the holotrichs (Isotricha) and the oligotrichs (Eggp- dinigm and Diplodinium) rapidly ingest starch grains in the reticulo-rumen. Certain Species of Entodinium appear to be .,;..,.2..1r5nf 51' k ' “U i,“ u I DI I. . v H r y: ”he pad” ‘ A ‘. in ‘ A \ ‘ ‘1 p ‘ ‘v' .‘ m. .v 17“ 'I (full-It‘s. “‘e On‘\ , . :21: 351' Plyturgh, ‘ 1 6 J 'I. !.’ r ”A ‘n ‘1‘ .Leu .‘L/LD V. A mm, 1 . .......-,se 9:1 m “H“: ‘r. ‘“’\}?’\7 fi““‘ N NA‘J‘JU ".‘1';:b; t. ..‘. 'NH "(3 l ‘S‘flvfl'h‘w n1 “II -“ 1| \ K 13"" ”I; “'13 web” 4“ b. d t“ ‘A’ ‘\"IF\\1~) .1 4,. u .g' :. a J: (Arc ‘ v‘v..~ “ _3";ro .f‘.v “..', + "In. ' K "‘ -b 1,. :‘Nn I.:«J?u“ N'A (..':p v. .‘,| afar \ 15%,: ‘0 cv‘ ‘Vu I.~, mfg“ " i :‘n‘ 109 the predominant starch ingesters among the rumen ciliates and, if the ration is fairly rich in starch, may in fact be virtually the only genus represented in the rumen (Van der Wath and Myburgh, 1941). Several starch-splitting enzymes have been isolated from the rumen holotrichs. Heald and Oxford (1955) found invertase, inulinase and levanase.activity in supernatant extracts of holotrich protozoa. Kore recently Mould and Thomas (1958) have added two (l-amylases to this list and a weak maltase activity has also been demonstrated. It is fairly certain, particularly with the holotrichs, that the protozoa attach starch and the soluble sugars by means of their own enzymes and not through symbiotic bacteria. Rations high in starch are characterized by a lactic acid fermentation in the rumen. Hungate et al- (195?) found that starch resulted in a large production of lactic acid and a consequent modification in the rumen fermentation products in sheep. When diets containing high prOportions of flaked corn were fed to lambs by Phillipson (1952), high and sustained concentrations of lactic acid were observed and the ratio of acetic to propionic acid was unusually low. Butyric acid was also produced to a lesser extent. Similar results have been obtained with cows by Waldo and Schultz (1956) and Balch and Rowland (1957). According to Oxford (1958) it is probable that most of Use rumen propionate arises by lactate fermentation and/or by ' . IA u ‘:1:I ) u.v»¢~J ‘. ¢'L'-J ‘ e “41””ng hc: ”no-nu ‘4 A '.'¥ . o 't-- n . 1"th § u... ‘4’] {c He ' I n , V . ..‘.“M‘i‘ A ’ v.‘.'4u ‘ V “F a: I II. n" me ”.1” '1:- ..h A. ‘2 tin I ..v ..’. ‘I -.‘ ..2"-r~‘ w. w“ ‘. .I‘ \"":“:3F .. t. ) :I; .'u A ‘ I Pl ‘.‘ s ..‘“ I’I‘:" cl“ 0‘ “J '1“ g ".:Q ‘n. V I ’ U‘l .| . . M. g ‘. ..‘.v s "A I;-H‘ ~ ‘ I . l‘, l- “ 1N~ sq,‘ 110 decarboxylation of succinate. The conversion of lactate to propionate has been studied by Johns (1951), Gutierrez (1953), Hueter g§.gl. (1956), Waldo and Schultz (1956) and Elsden g3 gl. (1956). Microorganisms in the rumen have, among other criteria, been characterized by their ability to ferment various types of carbohydrates as well as by their endoproducts of fermenta- tion. The species of well authenticated rumen organisms attacking starch and soluble sugars are in the main not the same as those attacking cellulose and pentosans. Among the bacteria, the many faceted biochemical potentialities of Streptococcus bovis are most noteworthy. They are never absent from the rumen. Starch, inulin, glucose and many other soluble sugars are readily fermented to lactic acid (Hungate g3 g1., 1952; MacPherson, 1955; Hobson and Mann, 1955; Hobson and MacPherson, 1954; Mann g3 g1., 1954; Baumann and Foster, 1956). This organism is likewise involved in the synthesis of dextran from sucrose (Bailey and Oxford, 1958). Starch and maltose, but not glucose, is fermented by Bacteroides amylo- philus to succinic, acetic and formic acids (Hamlin and Hun- gate, 1956). These same acids are also formed by Sgccinivibrio dextrinsolvens from the fermentation of a number of the sol- uble sugars, dextrin and pectin (Bryant and Small, 1956). Numerous soluble sugars are fermented by various Species of Lactobacilli with a resultant production of lactic acid u- .. . .. r I‘ n P c 3 :nM ......_...ou wen-.4 .Iv- I r-- nan-Luv; .v-.\ a: .34“ ' I an .“fiqw‘. :«nb‘. J .J. '.S '..:i‘:‘f\r‘!{ ?‘ N! - eel... V. J "it’s A . 0"; 43‘? : .i.lb' ’ { I‘L.‘ S .1 N: 3‘.‘ .‘w 2‘. i r... An I u- e ‘v: Cr‘a ..‘ . . . MU?! 1A t‘ ‘ ‘ d ’ ~ Il‘. v lts ~- '3 I‘- 111 (Huhtanen and Gall, 1952; Mann and Oxford, 1954, 1955; Briggs, U) V 1955; Baumann and Foster, 1956; Jensen et 31., 195' The end-products of glucose fermentation by the crescent form of Selenomonas ruminantium are primarily lactic acid, with lesser amounts of propionic and acetic acids (Bryant, 1956). It is noteworthy that propionic acid appears for the first time as a primary fermentation product, but this organism is not always present in the rumen and cannot be regarded as the main source of rumen propionic acid. Quin (1943) and Van der Westhuizen _£ggl..(1950) have shown that the oval form of this organism ferments both glucose and maltose but the end-products of their fermentation have not been characterized. With starch and soluble sugars the ciliate protozoa really come into their own as agents of fermentation. It appears fairly certain, particularly with the holotrichs, that the protozoa attack these carbohydrates by means of their own enzymes and not through symbiotic bacteria (Hungate, 1955; Oxford, 1955). Dasytricha ruminantium, a small holotrich ciliate, readily ferments glucose, fructose, galactose, sucrose, raffinose, cellobiose, B-glucosides and levans, but not starch, to lactic, acetic and butyric acids, with lactic acid predominating (Heald and Oxford, 1955; Gutierrez, 1955; Gutierrez and Hungate, 1957; Howard, 1957). The large holo- trich ciliates, Isotricha intestinalis and Isotricha prostoma, ferment glucose, fructose, raffinose, sucrose, levans and in... to .I,'.n.. “fl I. ~ "'ub, ' "Pr; , ‘H ..v '1’. N... h . :-kF§l ‘I"'- l , _‘ I‘V. ‘ a ‘- $ K... : .VL ’A, ... . ‘\ ~"I u..’ Y ”U. ‘.‘ ., ..- . _'-‘ ~ “at, H‘.‘ I .-\ 2 .. -“'- ~h ..‘. 1" ‘ K ‘a ‘ I. n 112 starch to lactic, acetic and butyric acids. Many of the lactate fermenting organisms, with the excep- tion of Veillonella ggzogenes which ferments only lactate (Johns, 1951), also ferment a number of the soluble sugars (Huhtanen and Gall, 1952; Elsden g3 g1., 1956; Hobson g3 gl. (1958; Gutierrez, 1955). The end—products of their fermenta~ tion are prOpionic, acetic and butyric acids, with propionic acid predominating. Other organisms readily fermenting many of the soluble sugars are the proteolytic organism Bacillus licheniformis (Appleby, 1955), the cellulolytic organism Clostridium loch- headii (Hungate, 1957), and the pentosan-fermenting organisms Butyrivibrio fibrisolvens (Bryant and Small, 1956) and Eggs teroides amylogenes (Doetsch g; 31., 1957). Butyric, acetic and formic acids are the major end—products of their fermente- tion. The prOperty of storing a polysaccharide within the cyto— plasm has been repeatedly demonstrated and is apparently char- acteristic of a number of the bacteria associated with the fermentation of starch, glucose and many other soluble sugars in the reticulo—rumen (Quin, 1945; Van der Westhuizen t g1. (1950; Hungate g§_gl., 1952; MacPherson, 1953; tobson and MacPherson, 1954; Mann ggigl., 1954; Hobson and Mann, 1955; Baumann and Foster, 1956; Doetsch §§.§l-. 1957; Bailey and Oxford, 1958; Oxford, 1958). The protozoa, eSpecially the ‘ n‘vnianc : I w."‘ o‘b-‘U’ v‘ :5 him, 1 '°: .9: ~¢ it y, I ..J (L) F11 3431;” Q In ’I-gnnvL ‘ 2 \Atd '21:? "A "i . 4>u » "E “No" “V .v' *. Q I“ “v? I H w r L. kin} v“ . :‘I113:e ‘03: :d a I 41:!" (1 ("Eva .3 v 7‘ .+ «t: flr‘i 'fl. In”; (‘Pp H" 1 :‘1‘ a," 'M'. ,1, ‘. 1.. _fl nor 5 u... 115 holotrichs, are particularly active in this respect (Sugden and Oxford, 1952; Sugden, 1953; Heald and Oxford, 1953; Weller and Gray, 1954; Gutierrez, 1955; Hungate, 1955; Oxford, 1955; Gutierrez and Hungate, 1957; Howard, 1957; Oxford, 1958). Masson and Oxford (1951) indicated the polysaccharide reserves in the holotrichs were like starch rather than glycogen. This was subsequently confirmed for Forsyth and Hearst (1955) who showed that the carbohydrate was an amlepectin with no trace of amylose and yielded only glucose on complete acid hydrolysis. Baker (1942) and Van der Weth (1948) have suggested that a large portion of the carbohydrate ultimately utilized by the ruminant is made available via a microbial polysaccharide- Reserve starch storage does not seem to be a major mechanism by which carbohydrates are supplied to the host. Masson and Oxford (1951) showed that a yield of about 1 g. of protozoal starch per kilogram of rumen contents could be consistently obtained from a fistulated hay-fed sheep, the ration being virtually free from vegetable starch. Heald (1951) estimated that in 24 hours approximately 5 g. of a "glucose-containing carbohydrate" was present in the micro-organisms of the in- gesta passing through the abomasum of a sheep fed on chopped hay (starch concentration not Specified). Weller and Gray A (1954) fed sheep all-roughage rations containing from 3 to 150 g. of starch per day and calculated, by means of starch/ lignin ratios, that only 1 to 8 g. of starch reached the My : "‘I‘:“H f it}. '4 .' ‘. ":M" was“ v.5 y u .- | .. .q. \- , ~~.x~ 114 abomasum. These investigators concluded that the quantity of starch passing to the small intestine was not sufficient to be an important nutritional factor in sheep, even when diets high in starch were being fed. It seems unlikely that such would be the case if feedstuffs of widely different densities were fed, i,§. hay and ground corn, in which considerable starch might escape fermentation by rapidly passing from the reticulo- rumen. According to Hungate (1955) reserve polysaccharide stor- age plays a more significant role as a reserve source of energy during periods when carbohydrates are not readily available for fermentation and enables the protozoa to maintain a rela- tively constant output of fermentation products. The fact that the reserve polysaccharides rapidly disappear on starva- tion of the animal lends support to this premise (Oxford, 1951; Sugden and Oxford, 195?). Using washed suSpensions of mixed holotrich protozoa Heeld _e__i; a}, (1952) and Heald and Oxford (1955) obtained molar ratios of C02, hydrogen and volatile fatty acids of l.O/1.0/2.0. Lactic, acetic and butyric acids in ratios of 2.0/1.0/2.0 and traces of prOpionic acid were identified. Reserve polysaccharide formation amounted to some 50 percent of the substrate. In the absence of substrate the products of endogenous fermentation included relatively more acetic and butyric acids and less lactic acid than were formed during the fermentation of carbohydrate. 3“.” "Wk:- *‘3 f Y n [‘3 ‘0 ‘ JUII Puf -ul. Edi ,- mu . .I.I‘ I o . ~ ._' up“: “o‘er 4 ‘ ‘~\..,, : 4‘": u v, 3 Rye . J ’-J£.' .' 'I C \,:e -22?" .. -H‘ ‘~ l ‘\‘ .. . h‘ ‘. In ‘.' \ J v \ . In-" .D - 3. ‘I J ., .‘P \ " ' h V I I s 77“, \\-! ._ ‘ 3 . I» . ..a \. ~ ._ ‘ ‘\ . . . \‘ , 115 Gutierrez (1955) performed similar studies and found the same acids but obtained relatively greater quantities of lactic acid. It has been recognized for many years that short-chain fatty acids are produced by the microbial fermentation of car- bohydrates in the alimentary tract. Accurate data on the indi- vidual acids were not reported, however, until partition chromatography became available as an analytical procedure for the analysis of complex mixtures of these acids (Elsden, 1945). More recently gas-phase chromatography has been used to effect separation of-the acids and their isomers (Annison, 1954). By these means acetic, propionic and butyric acids have been established as the major components of the mixture of fatty acids in the rumen fluid of sheep and cattle as well as other ruminants. Acetic acid almost always has been present in the rumen in the greatest amount and the proportion of propionic acid usually has exceeded that of butyric acid. Ample con- firmation of this with a wide variety of diets has been ob- tained by Elsden (1945), Elsden gt el~ (194a), Kiddle §§_gl. (1951), Schambye (1951), Gray and Pilgrim (1951), Gray gt g1. (1951), McClymont (1951), Tyznik and Allen (1951), Gray gt 3;. (1952), El-shazly (1952), Phillipson (1952), Annison (1954a, 1954b), Carrol and Hungate (1954), Johns (1955), Emery gt 3;. (1956), Halse and Velle (1955), Annison gt El. (1957), Reid _t 51° (1957), Balch and Rowland (1957), Balch (1958), Stewart O, u 5| Ca' ($V -— . it": Q . i. v- . .. .. - ”up ‘ ‘ i "..' I.’ 1' :‘v e w. ...h — i o. in, . _~\ .' 4 I ‘ fi~1v"x I II... I' ." n‘ ' t» ". ~ . : 's' 4 - \ QV'.', \ N". I y. ..‘. Q“ ‘._ “’00 u- ‘ -u u. l 116 t l. (1958) and Eusebio g3 g1. (1959). Some of the values for the relative prOportion of volatile fatty acids produced with different rations are summarized in the following table. Summary of the relative proportions of volatile fatty acids produced in the reticulo-rumen Volatile fatty acids (molar %'of total) Acetic PrOpionic Butyric Higher Gray et g1. (19527“ Sheep Hay 59-70 15-97 6-11 1-4 Annison gt al~ (19577 Sheep Hay 60-68 a5-5o 5-9 0.4 Stewart gt High hay al- (19587 Steers Low grain 57-51 ls-ao 8-19 9-5 High hay Balch (1958) Cows Low grain 55-59 19-20 7-14 4-6 Balch and Rowland High grain (1957) Cows Low hay 41-49 29-59 s-14 10-15 Phillipson High grain - (1952) Sheep Low hay 51-55 25-42 5-14 1-5 Eusebio et Concen- ' ,gg. (19597 Cows trates 54-58 55-45 9-15 8-16 Annison Concen- (1954) Sheep trates 57-70 18-55 9-29 1-10 Johns (1955) Sheep Pasture 50-59 91-50 12-17 5-10 Balch and Rowland (1957) Cows Silage 72-75 16-18 5-7 9-4 ‘1 '0.“ .1, (I g, .1... " 3‘ L. ’33", “A,“ i .......5 ‘v‘ :N..-O: fl‘ Q, ....n._ J‘ ‘. 1,“... ‘:“"+1 hua'.”" unh'i. - he " fl‘r Vs” 117 Although it is difficult to reconcile the wide variations ob- served between the data of different investigators it does appear that several generalizations can be made. The concen- tration of total volatile acids in the rumen increases after feeding for 2 to 6 hours, with diets containing no hay, small amounts of hay or hay in the finely ground state producing the greatest ranges in concentration. The rapid changes of con- centration of volatile acids in the rumen observed with high- concentrate diets suggest that such diets promote rapid fer- mentation. The mixture of volatile fatty acids found in the rumen of cows and sheep are qualitatively similar. On the other hand, there is considerable variation with diet in the relative prOportions of the individual acids. The percentage of acids higher than butyric increases with the amount of concentrates fed. Increased protein intake likewise increases the percent- age of such acids. As an eXplanation of this phenomenon, Balch and Rowland (1958) have suggested that the low-hay, high-concentrate diets, besides providing a greater intake of soluble protein, also promote the activity of the micro- organisms involved in the synthesis of higher'acids from the lower ones (acetic and prOpionic). Except with low-hay diets or diets consisting entirely of concentrates, the prOportion of butyric acid in the rumen increases with protein intake. It is not known with no-hay '° UPC . JV'AHC‘ ”7 .;.\":, p A :- ' oy- ‘l‘Ya lug! “‘..\. . ”an”: H- ‘ IIV-~v L.. ‘ ‘ ‘ (‘h "' a"! , W’s—u: v 9‘5: :J L): . I; I .‘ '0 118 or low-hay diets whether less butyric acid is formed or whether it is subsequently converted to other acids. The proportions of acetic and propionic acids appear to vary inversely. Except with diets containing ground hay, de- creasing the ratio of fibrous to starchy carbohydrates in the diet causes a decrease in the ratio of acetic to propionic acid. Mixed diets, in which the hay is finely ground, also decrease the ratio of acetic to propionic acid. Balch and Rowland (1957) contend that low ratios of acetic to propionic acid occur whenever there is a rapid production of fatty acids coincident with a reduced buffering capacity in the rumen liquid and that highly acid conditions appear to be unfavor- able to the development of organisms that produce predominantly acetic acid. According to Van Soest and Allen (1959) however, the ratio of acetic to prOpionic acid decreases not as a re- sult of decreased acetate production but because of an in- creased propionate fermentation. Lactic acid is found in the rumen in appreciable amounts only when rations high in starchy concentrates are fed. Since it is known that lactic acid is formed with other types of rations, it must therefore accumulate in the rumen only if the rate of fermentation to lactic acid exceeds its subsequent fermentation to volatile fatty acids. The quantity of volatile fatty acids formed cannot be determined.directly in the rumen because absorption decreases up: ..'. a... v9.“ \n. .gw‘ 119 the concentration of volatile acid simultaneously with its in- crease through fermentation. Stewart gt 3;. (1958) have in- directly estimated the production of volatile fatty acids in the rumen of steers fed different diets by determining the rates of volatile acid production ip 11339 and by following changes in the quantity of rumen contents at various times after feeding. Steers receiving about 19.5 kg. of dry matter (hay and grain) produced 2.9 kg. of volatile fatty acids per day. Of the total acids produced acetic acid amounted to 1.7 kg., propionic acid 0.6 kg., butyric acid 0.5 kg. and valeric acid 0.1 kg. Comparable estimates, both with regard to total production and production of the individual volatile acids, have been reported by Balch (1958) for cows receiving hay and grain. It is definitely established that the short-chain fatty acids from 02 to C5 are absorbed from the reticulo~rumen, omasum and large gut into the bloodstream. Examination of the blood draining these different regions of the tract (Barcroft gt_gl., 1944) revealed, however, that, apart from rumenal blood, only the blood draining the omasum and cecum contained volatile fatty acids in significant amounts. Examin- ation of the volatile acids of the contents of various seg- ments of the tract indicated that only the rumen and cecum contained appreciable quantities (Elsden gt_gl., 1946; Annison, 1954; Boyne at al., 1956; Badawy £3 31., 1958b). The concen- I . 1.“... 1 -. - a. in ' . a: v; 0' av.— ; ‘v '1 1 " ”a- u. -o ..', r. ~ _ . " do. "A. 'a ’ b l‘_ d -. ‘u ’ I. 0.. .j ‘ I» .4‘ n "; .... . . ‘«.o‘ t’ ‘31 .‘:- ‘x T“. .‘ s s. . .. .‘ 'v t . . .. A .' ‘k: -_~ Nj‘ n, . ‘n ‘I ‘o *_- ~. ":55 . \. . I .- u . ‘R ' ".o ‘J ~ ~ .I "h ,‘ p §'1 ] ‘10 \ I l' - ,H 1‘ , \..v a .i.‘ I‘ as .__ A. .5 '2 n ‘ i o" 5‘ :W 190 tration of volatile acids in the cecum is about three-fourths of that in the rumen, and since the cecum has only about one— tenth of the capacity of the rumen it is reasonable to assume that the contribution of volatile fatty acids from the cecum is relatively minor compared with that from the rumen. Several groups of investigators have studied the rates of absorption of the volatile acids from the rumen and the conflicting conclusions which have emerged no doubt reflect the different conditions under which the observations were made (Danielli 93 331., 1945; Gray, 1947, 194a; Kiddle §._t_ g__ , 1951; Reason and Phillipson, 1951; Johnson, 1951; Gray and Pilgrim, 1951; Pfander and Phillipson, 1953). In these in- vestigations the rate of disappearance of volatile fatty acids added to the rumen was used as a measure of their absorption. The results indicate that the rates at which the volatile acids leave the rumen vary with the pH of the contents. Accordingly, it has been proposed that only the free acid can be absorbed, however, it seems more likely that both the free acid and the anion can penetrate the epithelium and that changes in the rate of absorption as the pH falls are due to the more rapid uptake of the free acid as compared to the anion. In any event absorption occurs when solutions of pH 7.2 or more are in the rumen. At this pH the ouantities of acetate, propionate and butyrate absorbed from the rumen appear to be similar (Elsden and Phillipson, 1948). In contrast, at rt .Au 9.. no. u A. . 2. D. “i. .o i .ru v 5. gr. 0.5 Add Ah» . r a 2. .- V l’v I“. u. . I . a. n .v. 9.6. a...” Wuu- ‘ “..‘.kcJI'S I“ ..'- A‘J nr ... o‘qto u‘qn.‘ ’ U- i '1-4 4-8 its.“ .7. $1. nos I. ~“ «a. \u 0., . \ L. a; \tc .u. H. a! 1 ‘1‘ u.. I s ~l. ‘ ‘ .u 2. LI\ \w 121 pH 5.8 proportionately more butyric acid is lost from the rumen (Pfander and Phillipson, 1951). It is difficult to assess the exact significance of these findings in relation to events occurring during normal fermentation, as under these conditions there is a continual production and a varying con- centration of volatile acids along with minor changes in pH. A more direct method of determining the amounts of vol— atile fatty acids absorbed from the rumen and other parts of the alimentary tract lies either in the analysis of the blood draining the individual organs or in the analysis of portal blood. This technique has been adooted by Schambye (1951a, 1951b, 19510) who used the London-cannula technique to obtain successive samples of portal blood from conscious sheep under natural feeding conditions. By this means Schambye was able to follow the changes in concentration of rumen, portal and arterial volatile fatty acids when the sheep were fed various diets. The results suggested the relative concentrations of the total volatile acids in portal blood were generally cor— related with correSponding concentrations in the rumen but owing to the limitations of the London-cannula technioue suf- ficiently large samples of portal blood could not be obtained for partition of the volatile acids. More recently Lewis at gl. (1957) have develOped a method of catheterizing the portal vein in sheep which allows the repeated withdrawal of rela- tively large volumes of blood. By employing this technique Mlie I A .” Iv“ VJ ”t-“; '.'C{Ol p‘n~ 1:. vavoJu‘HP. :0: ,l' “MFG" .. .3 . J. ..u 2':'~‘§nn «3‘ ""‘V‘O‘Jlb v; 9 .‘ "A-, . . ' a J“ ~.‘, \$.x."‘ ‘90. y. .. '-‘ i. c .;‘:“A‘:c . , .. u,~‘.‘~ O u. . “ “v- 4. ‘l: 'l 9 n . . , ~ ~ « "an. CHO ‘ v "' V. ‘n “I. 'J ‘2 l 1 ‘5 _,_‘ ,. . ‘ ..‘-r“ ..‘, f. .' V \~ .‘32‘ .‘~ up? ‘1‘ '2‘. -,~ 1“ . ~ . a ”a a-"q -.~‘ V V‘. ".- n“ .1. has ‘v . I. . I x.‘ 5“. ‘ . \ "IV-1“: ‘ ‘ I \ ‘,. "‘a h! .- l‘y1 " '~. . "t? ..n‘ ' "J‘ . h ‘A . ‘\ ~,\. ~ . ' :C v” H U. ‘ . g. . 9. :~ ~‘ 192 for collecting portal samples and gas-phase chromatography for partitioning the volatile acids of portal and peripheral blood and of rumen contents Annison 93.21. (1957) have studied the absorption of the individual acids in sheep maintained on various diets. Data obtained by these investigators indicate that absorption of the individual acids, like that of the total volatile acids, was a reflection of their concentration in the rumen. This is in accord with the observations of Conrad it, al- (1958) with calves and McCarthy gt sl~ (1958) with goats. It should be pointed out in this regard, however, that metabolism of the fatty acids occurs when they are introduced into preparations where small pieces of surviving rumen epi- thelium are incubated in a suitable medium in xitgg (Penning- ton, 1952, 1954; Annison and Pennington, 1954; Pennington and Sutherland, 1956; Pennington and Pfander, 1957). The losses are greatest with butyrate and least with acetate. If the rate of absorption of these acids bears some relation to their rate of metabolism by the rumen epithelium, then the fact that the mixture of acids in the blood leaving the rumen is similar to the mixture within the rumen, except for a loss of butyrate, does not necessarily mean that the mixture absorbed is the same as that present in the rumen. Absorption from the reticulo-rumen and omasum must be extensive for only limited amounts of the volatile acids are found in the abomasum. Badawy at al. (1958c) have calculated e vs} 1 f U” ”a 5f, in 'y'uI 125 by means of volatile acid: insoluble ash ratios that 77 per- cent of the volatile fatty acids was absorbed from the rumen of sheep, with an additional 17 percent being absorbed from the omasum. Similar values were obtained by Gray gt 5;. (1954) who estimated from volatile acidtlignin ratios that 40—69 percent of the short-chain acids entering the omasum were absorbed. The actual quantities of volatile fatty acids absorbed from the alimentary tract can be determined directly if the portal blood flow is known. Methods of measurement have been devised for this purpose in unanesthetized sheep (Schambye, 1955b) and calves (Conner and Fries, 1958). Remarkably close agreement was obtained for the average portal blood flow in both apecies (57.0 and 57.8 ml./min./kg. bodyweight, respec- tively). If the average portal flow of 37 m1./min./kg. is applied to the portal-arterial differences in the concentra- tion of volatile fatty acids (Schambye, 1951a) then the trans- port of these acids by portal blood can be calculated. The average tranSport of total volatile acids in sheep feeding on diets containing hay alone, hay plus oats, etc. was about 191 m.mol./hr. This can be considered as only a tentative estimate, however, for portal flow rates on blood for which analytical figures are available have not yet been reported. Quantitative data on digestion of the conventional carbo- hydrate fractions (crude fiber and nitrogen~free extract) in 'I».. '1‘" 'I 124 the various segments of the alimentary tract have become avail- able only in recent years. Hale and coworkers (1940, 1947a, 1947b) estimated that 65 percent of the nitrogen-free extract (100% of digestible NFE) and as percent of the carbohydrates other than lignin end cellulose (100%13f digestible Other CHO) of alfalfa hay were digested in the rumen of fistulated cows during a 24 hour period. Twenty-seven percent of the crude fiber (58% of digestible CF) was digested in the rumen, with an additional 19.7 percent being removed posterior to this point. Paloheimo gt g1. (1955) and Makela (1956) employed a method introduced by Gray (1947) to calculate the digestion of nitrogen-free non-lignin organic matter in the reticulo—rumen of cows receiving timothy hay. About 60 percent of this frac- tion (85%10f digestible N-free non-lignin organic matter) was digested in the reticulo-rumen. Paloheimo pg 5;. sharply criticzed the method employed by Hale gt al. but ironically obtained values for the digestibility of 'carbohydrates' in the rumen which were quite comparable to those obtained by Hale and coworkers. Estimates of digestibility of the 'carbohydrates' in the reticulo-rumen and in the lower gut have been determined by Balch (l957) for fistulated cows receiving diets of widely different types. The diets ranged from hay alone or supple— mented with mangolds or dried sugar-beet pulp to a diet con— sisting of 24 lb. concentrates and 2 lb. hay. An average 58 a s‘. 'II“’ ‘ 3‘ ' ':_ :..- o 4“ vwwouf‘pa: d.u."Il “.Jl ancqf‘fi mint 0‘.& Us» o:nq:r. 3“ +.a- Invuu'v . i., t ‘:.X ““1“ “Mu-nay -w . FE" Ji‘ 3'“ '1, “H" v'. h'; o ‘- U o” , ..‘ ..'» -. ” IN PM I . .“H‘JF‘IJA‘J U a. b... " -§ 1’ Q . ..‘: 1:9; .. '32“ O ”Q .::‘l,' . -| an “He 1" ‘ Q“ “3,, \-.~ 5 ‘ '3: Cf at .~ ‘_ use b ’. ‘ I "u {p ‘. d“ n ‘vl‘l .‘ \, z. '11 ‘ ‘ £2)- .\- ‘-“D_‘ ' ' ~;Q o N! ‘ X iv. ' " § “3‘ a. v. VJNAA ,, . 3'th ‘. 5" “I 2‘! ..‘ .u 3.0“. y‘: . C:~ ., . ‘ . A" U [R ‘5“.7 V‘A-E 125 percent of the dry matter consumed by the cows was in the nitrOgen-free extract fraction and 90 percent in the crude fiber fraction. Thus 'carbohydrates' constituted almost 80 percent of the intake. The digestibility coefficients for nitrOgen-free extract varied from 43-76 percent in the reticulo-rumen and from 7-92 percent in the hind gut, with the digestibility of diets rich in concentrates being much higher in the reticulo-rumen than those consisting mainly or entirely of roughage. The amounts of crude fiber digested in the reticulo-rumen did not always exceed those digested in the lower gut. Coefficients of digestibility for this fraction varied from -8 to +61 percent in the reticulo-rumen and from 13-47 percent in the lower gut. There was a general trend for the introduction of increasing amounts of concentrates to de- press the digestibility of crude fiber in the reticulo—rumen. The results suggest, however, that when concentrates formed a large part of the diet the proportion of crude fiber digested elsewhere in the gut was somewhat raised. For example, with diets consisting entirely of hey the digestibility of crude fiber in the reticulo-rumen was 42-61 percent and for the lower gut 15-20 percent. With diets containing concentrates comparable figures were 10-38 percent and 16-40 percent. With a diet composed almost entirely of concentrates comparable figures were -5 to —8 percent and 41-47 percent. Rogerson (1958) obtained digestibility coefficients for nitrogen-free :v’nga‘ :3“! u‘laoV V "" {was v; w... Vi ‘ Q P‘q'bq n I1.I.U I} 5' [£- ..‘“ run“ ..‘ ‘ ‘svu D 00* '.~r" P... Q ‘ IQS extract and crude fiber in the reticulo-rumen and lower gut of sheep which followed the same general trends as those re- ported by Balch (1957) for cows. Kameoka and Morimoto (1959) have estimated rumen digesti- bility in goats by quantitatively collecting the ingesta pass- ing from the omasum. The digestibility of nitrogen-free ex- tract for a wide variety of diets ranged from 44-77 percent (66-97%;of digestible NFE) in the reticulo-rumen, with an additional 1-93 percent (5-34% of digestible NFE) being re— moved in the lower gut. The relationship between the level of concentrates fed and the digestibility of nitrogen-free extract in the reticulo-rumen was similar to that observed previously by Balch (1957) and ROgerson (1958). Almost all of the digestion of crude fiber occurred in the reticulo~rumen in this experiment, however, the authors were quick to point out that this is not always the case, for in previous investi- gations the largest part of the crude fiber was digested in the lower gut. Coefficients of rumen digestion for the 'carbohydrates' of a wide variety of diets in these experiments were within a comparable range deepite the fact that four different methods and three different apecies were used in their determination. This suggests that the functional role of the reticulo-rumen is much the same in the three Species studied and serves to emphasize the extreme importance of this part of the alimentary “a!“ If ..J_ U ..‘.‘quc ..'. ' U .‘Ad “'"-n-""; - 2.5.7.,“ . up... f“: i 3.4.: T. v “ "‘ '- oh s... 1‘ ”v . ..‘ .8 “ ” r“ ': b' ‘- ' w 'l. “1"? 2 in "..u: "v’ -. . t h“ ‘4‘ w I H‘ I I ‘.- \.“ Ja. n... 1; ..' . :71: \‘.'..ca :I,-\ A“ . ‘ ”‘c t. ‘- ." h. I ‘J‘Qr .. ..‘. .:“:I "“3. an 1?? tract in carbohydrate degradation. The nitrogenous constituents Our basic understanding of nitrogen metabolism in the various monogastric apecies which have been studied is con— siderably more substantial than our knowledge of what happens in the ruminant. It has been provisionally assumed that rumi- nants are not much different from simple-stomached animals both as to what they need to absorb from the alimentary tract and as to how they digest material entering the abomasum and passing along the lower gut. This latter aSpect of ruminant digestion has not been studied to any large extent, however no marked differences between ruminants and non-ruminants have yet been demonstrated. It is well known that this part of the alimentary tract is provided with the usual digestive enzymes; this is particularly true of the proteolytic enzymes which are routinely prepared for laboratory use from ruminant mate- rial. There seems to be little direct evidence that the re— quirements of the ruminant for essential amino acids are the same as for the monOgastric but the data presented by Black _t gl. (195?) appear to support this premise. A parallel line of evidence is provided by the experiments of Blaxter and Wood (195?) on the protein and amino acid requirements of calves in which rumen function had not developed. Though many of the details of protein, amino acid and urea breakdown and synthesis i: the r‘re: o 0' . if if "D P‘ L v J-o:v .- .1... bkcf 0‘ «a... u... 0‘ a I‘\.: n n .. “ -.‘-- .. 1 ". :I‘:‘Q F. "..~Ab 'I‘. ""01. H»: F‘rn $u...: I 9'" 3-: a0 ., r "4. u I- v; I) .‘ ’9 '1‘ .1. .. ice} ' 0 :‘.‘f, "we _ —.. Q“ .u t ‘\ ‘fi._ 4». \VI ~ .; \ \ .“\ -. IPB in the rumen are lacking there appears to be general agreement as to the main types of translocation and chemical transforma- tion that occur. These are illustrated schematically in Figure 2. Ruminants obtain most of their dietary nitrogen from plant materials although animal by-products and synthetic nitrogen- containing compounds are often included in the ration as sources of nitrogen. Proteins account for a large prOportion of the nitrogen present. These proteins have shown character- istic differences in their amino acid composition which have proved important, at least in relation to the supply of "essen- tial" amino acids to non-ruminant animals. Nonprotein nitro- gen accounts for a lesser proportion of the nitrogen and con- sists of free and bound amino acids, nitrates, alkaloids, purines, etc. Synthetic urea and various ammoniated products may also be included in the diet. In addition to the protein and nonprotein nitrOgen of the diet, the nitrogen of saliva entering the rumen may assume considerable importance both qualitatively and ouantitatively (Scheunert and Trautmann, 1921; Trautmann and Albrecht, 1931; KcDonald, 1948; McDougall, 1948; McGilliard, 1956; Johns, 1957; Somers, 1957). Thirty to 70 percent of salivary nitro- gen may be in the form of urea (XcGilliard, 1956; Johns, 1957; Somers, 1957). McDonald (1948) estimated that salivary urea nitrogen entering the rumen of sheep amounts to about 0.5 g. 1?9 Figure 9. Pathway of nitroaenous compounds alimentary tract in the . I‘. I a \ H I" “*HCK My ..‘ g.’ V 41"?" ~: _. l mfl 130 DIETARY NITROGEN SALIVARY NITROGEN Proteins Free amino Nitrates Urea U/rea cin Polypeptides acids, etc. Amides :\ - Liver Polypeptides acids, etc. i' i,_ N-free* compounds Microbial /' protein [I ABOMASUM V V Y Y Proteins Polypeptides Amino acids Pepsin + HCl—‘r _ Gastric mucin NH3 ! I t y i ' Intestinal enzymes-—~ .i PFOTSlOS DUODENUM Polypeptides . . . . Amino OCldS +T’“ EpithllOl dEDI’IS Intestinal mucin__.....-_.si.. NH xx 3 “NM—um- -..._. ._ .__._.__., -_,__...____-..._._; *Converted to microbial ponsoccharidss and to lower fatty acids. m p Mn; “”3: :..: 'Aj“ . \ in "F a! ‘58 n: :.‘ “Q ‘5 '03. lauA“ fr ‘ u. ‘ “U, V [ ~ 0‘ . "I A. 1 2“ ‘ ..' LYLE u“ , u "In. {R Q}: "“3'35 i L... 31 . r “A h ““vIEu- I " 'I! ‘ 5‘ r, ‘ h ‘ “I: i. n-Lhrv: 0|. ‘ a i ... “..'.” .I tut‘ 1.1.9: .r .“ ‘ ow, b V..- . w.‘ y. “ a H! J1 u‘ a lit L 3 L" ‘ 3 nix ‘ ~ I . t V' ..“1‘Y,. ‘ 11:1“: ‘0 ”‘5' J1 urn: .{r ,3" . Utter’ei : 'I ~¢ u, G {’c""| "‘ V‘ “~— 33... K ‘ .u: 4‘ A ‘ I s‘an tan :3 a J 2 i p as l,‘ \\ " CH 151 per day. On the basis of data obtained by Somers (195?) 0.7-0.9 g. of nitrOgen can enter the rumen of sheep via the saliva each day. McGilliard (1956) estimated that a minimum of 10 g. of salivary nitrogen passes into the rumen of mature cows each day and that under certain conditions values as high as 30-40 g. of nitrOgen in 94 hours may be possible. Chalmers and Synge (1954) Speculated that free amino acids and urea of the blood might pass into the rumen through its wall since the concentration gradients between blood and rumen liquor are such that substantial quantities could pass by simple diffusion. Raynaud (1956) observed a considerable increase in the total rumen nitrOgen of sheep which were fed nitrogen-poor, carbohydrate-rich diets and theorized that salivary nitrogen participated only in part in augmenting the nitrOgen in the rumen. Recent data presented by Houpt (1958) indicate that in sheep fed timothy hay, starch and sugar the amount of urea passed into the rumen through the rumen wall was 4.9 millimols of urea nitrogen per hour as compared to only 0.5 millimols of urea nitrogen per hour in the saliva. Passage of urea into the rumen through the rumen wall has also been observed by Simonnet ££.£l- (1957). There appears to be no eXperimental evidence regarding the passage of free amino acids into the rumen Via the rumen well. So far as is known there are no proteases present in ruminant saliva (Wegner at gl., 1940), nor is there any efiiezce tr rsticulo-rt I. '. t .:e:e ati "q:" 8‘ ‘L- c a.-." .5..‘ is, 7 ' Leel ' 85‘s.. 2'; hu‘ ‘ _.. Suvalys 0'...“ ‘1‘. u u U.‘ u c .ll.l‘fl‘ “ “do 9 1 152 evidence that proteolytic enzymes are elaborated by the reticulo-rumen itself. Any proteolytic activity must there- fore be attributed to the microflora and/or microfauna of the rumen either by the secretion of extracellular proteases or by intracellular enzymes liberated into the rumen after death and autolysis amongst the microbial population. Sym (1938) found rumen contents to be strongly proteo- lytic but observed little if any activity in the supernatant liquor. This finding was confirmed by Pearson and Smith (1945c) who obtained clear evidence of proteolysis with casein and gelatin whereas with blood meal net protein synthesis occurred. They ascribed this phenomenon to the relative in- solubility of the blood meal. Hoflund §t_g;. (1948) observed that fibrous proteins (strips of muscle) were hydrolyzed only slowly in the rumen. McDonald (1952, 1954), taking advantage of the peculiar solubility of zein in aqueous alcohol, meas- ured its disappearance from the rumen of sheep. He estimated that 40 percent of it was broken down in the rumen and postu- lated that more soluble proteins might be attacked more ex- tensively. Further evidence of proteolysis of a wide variety of proteins has been obtained by Chalmers gt al. (1954), Chalmers and Synge (1954), Annison g§,gl. (1954), Warner (1956a, 1956b), Annison (1956), Gray and Pilgrim (1956) and McDonald and Hall (1957). The eXperiments clearly indicate that the nature of the protein is an exceedingly important 322:0: in 1‘» “.15 pm teal: I It .5 s.r.lar l Supper :19: is 11? "iii-3i we! 3; 1353; ' v 1'5 5.7 the , "m Pal ‘M‘ .h. ‘L 133 factor in its rate of hydrolysis. Warner (1956b) found that the proteolytic potency of suspensions of rumen microorganisms is similar with sheep on a wide variety of diets and does not vary with the composition of the diet as does the power to produce ammonia from amino acids. Supporting evidence for the breakdown of protein in the rumen is likewise furnished by studies of the apparent digesti- bility coefficients for protein (Hale gt al., 1947b; Gray at g;., 1953; Gray and Pilgrim, 1956; Balch, 1957; Hagan, 1957) and by the increase in numbers of rumen microorganisms on in- creasing the prOportion of protein in the ration (Mair and Williams, 1950; Williams and Mair, 1951; Williams at al-. 1953). Hale 23 pl. (1947b) used complete removal of ingesta from the rumen of fistulated animals in conjunction with the lignin-ratio technique to estimate the apparent digestibility of protein in the rumen. Although several criticisms have been leveled at the sampling procedures employed by these workers it appears that the average digestibility coefficients for protein are within the range found in other experiments. Balch (1957) applied the lignin-ratio technique to samples of ingesta taken at frequent intervals in close proximity to the reticulo-omssal orifice to determine protein digestion in the rumen. With diets consisting mainly of roughage and contain- ing only small amounts of protein, the apparent digestion of jprotein in the reticulo-rumen was low, suggesting that there 154 was either little or no absorption of nitrOgen from the rumen or that any absorption of nitrOgen was balanced by the secre— tion of endogenous nitrogen into the rumen via the saliva and rumen wall. In contrast, diets containing large amounts of concentrates and protein in the form of groundnut cake showed evidence of a considerable loss (12-54 percent) of the dietary nitrOgen by absorption from the reticulo—rumen. Evi- dence for even larger losses of nitrogen from the stomach of sheep has been reported by Gray and Pilgrim (1956). Applying the lignin-ratio technique to samples of ingesta obtained from the reticulo-rumen, omasum and abomasum after slaughter, these authors found that the amount of dietary nitrogen reaching the abomasum was equivalent to about 40 percent with good- quality alfalfa hay and about 60 percent with a mixture of wheaten hay and alfalfa hay. The remainder was presumed to have been absorbed as ammonia. With a mixture of wheaten hay and straw it appeared that more nitrOgen reached the abomasum than was present in the food. Similar results were obtained with other low-nitrogen rations of wheaten hay. It was assumed that the additions of nitrogen to the stomach compart- ments were of endogenous origin. By totally collecting the ingesta passing from a re-entrant fistula placed in the pyloric duodenum of sheep Hogan (1957) was able to directly determine the amount of nitrogen passing from the stomach and to estimate, by difference, the extent of nitrogen loss. On 1'55 basis of 9’ "I ' a .-. .-e aibes saw” t‘H ”..'“;le -AJ 5 ' 4 ..'.e 8X4 ..l ' -=' 52m t It!“ O "'2" fwd ' «p...» cm. I \ I . E :‘E ‘a .v erd 1‘ fl v t.‘ v: P 155 the basis of 12-hour collections it appeared that 56 percent of the digestible nitrogen was lost from the tract before reaching this point. The existence of proteolytic bacteria in the rumen has been shown by cultural studies. Huhtanen and Gall (1952), Bryant and Burkey (1953), Appleby (1955), Warner (1956b) and Hunt and Moore (1958) have isolated organisms under conditions and in numbers that suggest that they are members of the normal rumen pOpulation. Warner (1956b) has clearly demon- strated that toluene-treated suspensions of rumen bacteria release primarily amino acids from the proteins casein and ardein. In the absence of toluene bacterial deaminases were active. The presence of proteases, unlike the deeminases, does not depend to any great extent on the presence of readily-attacked protein in the diet. Extracts of acetone— dried powders of the bacteria show proteolytic activity. Available evidence indicates that rumen protozoa are also proteolytic with ammonia appearing to be an end product of their metabolism (Warner 1956b). Much of the ammonia produc— tion in the rumen in the absence of substrate appears to be. due to endogenous metabolism of the protozoa. Extracts of acetone-dried powders and extracts prepared by freezing and thawing protozoa contained active proteases. Employing an artificial rumen apparatus Warner (1956b) found that about half of the nitrogen and carbon of added casein could be fisavered "w=tion. IoEvu . Pg ’ ‘ .. ‘93 1.0, I ‘ ‘ ‘ !:.c :1 a ..‘. | . A _ K... CZI‘LL M'M‘ Hans! mated f igéliE e triilee .. 156 recovered as ammonia and volatile fatty acids at the end of digestion. Most of the remainder could not be accounted for analytically and was presumed to have been used for microbial growth. If starch as well as casein was added to the arti- ficial rumen the production of ammonia was lowered. This was assumed to be due to the increased utilization of some break- down product of casein for microbial growth since there did not appear to be any effect on protolysis or deamination. Urea entering the rumen is very rapidly hydrolyzed to ammonia. In fact it is difficult to detect urea in rumen con- tents at any time after administration. This has been con- firmed not only by ig_yizg determinations on fistulated ani- mals but also by in ziggg incubation of urea with rumen con- tents (Wagner gt al,, 1940, 1941; Pearson and Smith, 1943a; Bouckaert and Oyaert, 1952). When urea was incubated with a suspension of rumen microorganisms Sirotnak gt El- (1955) found that carbon dioxide as well as ammonia was produced in the eXpected quantities. Pearson and Smith (1945b) showed the presence of an active urease in toluene-killed rumen organisms and studied its enzynic activity. Mansson and Anderson (1956) and Holtenius (1957) have isolated from the rumens of sheep a number of strains of Bacillus and coliform bacteria which possessed the capacity to reduce nitrate and nitrite. Several strains of Seleno- monas ruminantium, isolated from the bovine rumen, were also found to be ca Ezltems and ability to red :25: rumen or aérently lac (.11 apiro t used direct L771? men a :3 be interned "5N -' arsed thes ’39 wet likel 2‘7 he exDecte '61" I ‘5‘ “.u‘i S for tj 5"“ ”"58 8Che 137 found to be capable of reducing nitrate (Bryant, 1956). Holtenius and Nielsen (1957) have shown that the fungi Absidea ramosa and ngarium from the rumen of sheep have the ability to reduce nitrate and nitrite. Information about other rumen organisms which can reduce nitrate or nitrite is apparently lacking. Sapiro g3 g;. (1949) and Lewis (1950, 1951) have pre- sented direct evidence of the conversion of nitrate to ammonia by the rumen microorganisms. Nitrite and hydroxylamine appear to be intermediate stages in the reduction. Holtenius (1957) confirmed these observations but postulated that conditions are most likely much more complicated and that other reactions may be eXpected to take place. He summarized various possi- bilities for the metabolism of nitrate in the rumen in the following scheme: Nfs (1) N037——.N021——-NHQOH =:RCNOHCOOH——a-RCHNH2000H (2) +RCOCOOH +RCHNHZCOOH ) 1 RCHOHCOOH + N + H20 (5) 2 1. Reduction to ammonia. 2. Reaction with keto-acids to form amino acids. 3. Reaction with amino acids to form gaseous nitrogen. wanal- ciatle conco; 23:9: grezin axis was :2: ccncentj 5123 Eouckae sclose con 12!! in the j 138 McDonald (1948) and Johns (1955) have shown that appre- ciable concentrations of ammonia occur in the rumen of sheep after grazing on pasture. In addition McDonald observed that ammonia was absorbed directly from the rumen giving signifi- cant concentrations of free ammonia in the ruminal veins (see also Bouckaert and Oyaert, 1952). Lewis gt g1. (1957) found a close correlation between the changes in ammonia concentra- tion in the rumen and in the portal blood thus indicating that rapid transference of ammonia occurred through the rumen epithelium into the venous blood draining the rumen. Since there appeared to be no mechanism regulating the absorption of ammonia it was assumed that transference was effected by simple diffusion. Raynaud (1957) followed the pattern of evolution of nitrogenous materials in the rumen of sheep which had re- ceived ground a1fa1fa.hay via rumen fistula. Ammonia levels in the rumen increased rapidly during the first two hours, decreased for approximately eight hours and then increased again. Opposite fluctuations in total rumen nitrOgen were observed. Head and Rock (1955) suggested that under condi- tions of high rumen-ammonia production ammonia may pass in quantity from the rumen to the small intestine. Raynaud . (1955b) found that, although ammonia nitrogen made up a considerably greater preportion of the total nitrogen in the rumen than in the abomasum or duodenum, it was not without significance in these segments of the tract. Lewis gt a1. {1557) have all intes: that free a?! 1: periphers 1:: liver, t £5315! for 39358 V8: 139 (1957) have shown that ammonia absorption can occur from the small intestine and is, in reality, extremely rapid. The fact that free ammonia is normally absent or in low concentrations in peripheral blood suggests that ammonia is metabolized in the liver, urea being the end product of metabolism (Lewis ‘g§‘§;., 1957; Lewis, 1957). McDonald (1952) found that both casein and gelatin readily yielded ammonia whereas insoluble zein was attacked much more slowly; feeding of starch decreased the concentration of ammonia observed. Chalmers gt g;. (1954), Chalmers and Synge (1954a, 1954b) and Annison gpigl. (1954) similarly observed substantial differences in the extent of ammonia formation when casein, herring meal, groundnut meal or grass was fed. Parallel evidence of differences in the utilization of the various proteins were obtained. The marked effect of starch on rumen ammonia levels was likewise con- firmed (see also Lewis and McDonald, 1958). The extent of ammonia absorption from the rumen and its subsequent conversion to urea, reentry into the rumen, partial excretion in the urine, etc. has not as yet been determined; however, Lewis 93 §;. (1957) and Lewis (1957) speculate that a 15-30 percent loss of ingested nitrogen appears possible when the rumen ammonia concentration is high (40 m. mol./1.). Lewis (1955), Annison (1956) and Blaizot and Raynaud (1957) have demonstrated that free amino acids are always present within the rumen contents at low concentrations (Ll-4.0 fig. tese amino 1 *3 Pméuct 1:: ~_\ 5.,411 p01“ 1 "“~ Fro-ducts assizileted .‘r. -. atitle . (11’ Ge» ‘33: + .o “3‘41 11:; E 140 (0.1-4.0 mg. N/lOO ml.). There appears to be no evidence that these amino acids are absorbed from the rumen (Annison, 1956). El-Shazly (1952a, 1952b) showed that amino acids are deaminated anaerobically, with the production of ammonia, carbon dioxide and fatty acids; this has been confirmed in a number of more recent studies (Sirotnak g; gl., 1953; Lewis, 1955; Warner, 1956b). Ammonia thus appears to be the principle nitrogenous end product from amino acids in the rumen. Chalmers and Synge (1954b) point out that free amino acids are found as normal , end products of proteolysis and are subsequently either assimilated by the rumen organisms or destroyed by fermenta- tion. Furthermore, the ability of rumen microorganisms to ferment amino acids seems to be enhanced when the animal is on a diet giving rise to extensive ammonia formation. On other diets, as El-Shazly (1952b) has shown, deaminative attack by washed suspensions of microorganisms was less rapid. This seems to imply that certain species of microorganisms which do not flourish when the animal is on a relatively insoluble or low protein diet, are concerned in the fermentation of amino acids. That rumen microorganisms synthesize their body protein from simple nitrogenous components of the diet has been re- peatedly demonstrated, however, little is known as to the ex- ‘ tent to which these organisms use extracellular ammonia, free amino acids or peptides as their source of nitrogen. It has been unequivo 1:111?! t0 3) be: with re1 arcs of M1 135?; Duncan istic mac! 1!. ' ..crgeiic su, r; 5:91:01, I (55 to "'5' 810 13:; ‘R ML. { We g :N. “6131‘ bv I w ‘i ii! i 141 been unequivocally shown that rumen microorganisms possess the ability to synthesize an ample supply of amino acids for the host with rations in which urea was practically the sole source of nitrogen (Loosli gt,a;., 1949; Bouchaert and Oyaert, 1952; Duncan gt g;., 1955). Further evidence of their syn- thetic capacities is shown by their ability to incorporate inorganic sulfur into the sulfur-containing amino acids (Block and Stekol, 1950; Block gt a1,, 1951; Emery gt §;., 1957a, 1957b). The difficulties involved in trying to determine the ex- tent of conversion of food protein to microbial protein have been pointed out by MbNaught and Smith (1947) and McDonald (1954). Data obtained for hay-fed sheep by Gray gt g;. (1953) suggest that about 50 percent of the food nitrOgen was con- verted to microbial nitrOgen in the rumen. Using a new ex- perimental approach McDonald (1954) estimated that, when zein was fed to sheep as the major nitrogenous component of the diet, some 40 percent of the zein was utilized by the rumen microorganisms for synthesis of their own proteins. As zein was very slowly attacked, and as the ammonia liberated never accumulated in significant amounts in the rumen, it was pre- dicted that other proteins which yield ammonia more readily would give a greater degree of conversion. This has been verified by McDonald and Hall (1957) who fed sheep a ration in which casein provided 87 percent of the dietary nitrOgen. is; estitetec‘ :‘egraied in t} 3121 prateins It is no ”181‘. b1 \) 350, J 142 They estimated that at least 90 percent of the casein was degraded in the rumen and utilized for the synthesis of micro- bial proteins. It is now generally agreed, though the evidence is cir- cumstantial, that much of the protein passed from the rumen and digested in the abomasum and small intestine is contributed by the bodies of the bacteria and protozoa which have developed in the rumen (Baker, 194:5; Masson, 1950; Pounden _e_g a1” 1950). Decomposed bacteria can be identified in the cecum, but not protozoa (Baker and Harries, 1947). Moir (1957) points out that most protozoa are rapidly broken down in the omasum (see also Gray 33 g;., 1954), whereas the count of bac- teria doubles. Changes in the microscOpic structure and stain- ing reaction of the bacteria commence at this point. The amino acid composition of mixed rumen proteins (Loosli gt_al., 1949; Bouchaert and Oyaert, 1952; Duncan gt_g;., 1955; Chance gt a;., 1955; Oyaert and Bouckaert, 1955) and of proteins from rumen microbial preparations (Tsuda, 1955; Holmes §§.g;., 1953; Weller, 1957) confirms their potential value to the ruminant. Both bacterial and protozoal proteins have reason- ably high biological values (Reed _e_j; 121-. 1949; McNaught _e__t_ 21., 1950, 1954) however the digestibility of bacteria has been found to be lower than that of protozoa when fed to rats (Johnson _e_t 91-. 1944; McNaught 9.3; _a_l_., 1954). Raynaud (1955a) followed the changes in nitrOgen concen- ration of t! '15: had be :itr'cgen cam :ttie tract 327391 sugg iteaied in ' Ii-titmgen 143 tration of the ingesta through the alimentary tract of cattle which had been fasted 24 hours prior to slaughter. Increased nitrOgen concentrations were observed at each successive level of the tract (reticulo-rumen, omasum, abomasum, duodenum). Raynaud suggested that the rising proportion of nitrOgen depended in part on the relatively faster absorption of the non-nitrogenous constituents and in part on the addition of nitrogen from secretions and/or desquamated epithelium. Boyne 93 gl. (1956) and Regerson (1958) observed enhanced concentra- tions of nitrOgen in the omasum of sheep which had received rations consisting predominantly or entirely of concentrates (corn). Diminished nitrOgen concentrations were noted by Regerson when a preponderance of grass hay or an all-grass-hay ration was fed. On the other hand the effect of these rations on abomasal nitrogen concentrations was reversed; the prOpor- tion of nitrogen in the abomasum increased on the high-hay rations but exhibited a sizeable decrease on the high-grain rations. NitrOgen concentrations were substantially enhanced in the small intestine in all experiments (Raynaud, 1955a; Boyne gt,a_., 1956; Rogerson, 1958). These results, as do the earlier findings of Raynaud, suggest a considerable addi- tion of endogenous nitrOgen into the alimentary tract. Recent observations reported by Badawy 93 a1. (1957) and Hogan (1957) lend support to this premise. Regan estimated that about 0.6 g. of nitrOgen was secreted into the abomasum of sheep each L: Eliibitet t'igersln, 195 7.5:? nitI‘Oge rearing the (5.33195. by J 144 12 hours, while nitrOgen secreted into the small intestine during the same period was considerably greater (6.5 g.). Boyne at al. (1956) further indicated that the nitrOgen con- centration was greatest in the proximal small intestine and diminished distally. NitrOgen concentrations in the cecum and colon were substantially lower than in the small intestine and exhibited only minor fluctuations (Boyne _e__t_ 9.1.. 1956; Rogerson, 1958). The results strongly suggest that the diges— tible nitrOgen has, for the most part, been removed prior to reaching the cecum. Corroborative evidence of this has been reported by Hogan (1957) who found that losses of nitrogen from the large intestine of sheep were negligible. In a continuation of previous studies on total nitrOgen Raynaud (1955b) determined the concentration of various forms of nitrogen in the reticulo-rumen, abomasum and duodenum of cows slaughtered 24 hours pggt_ggggm. Protein nitrOgen in- creased appreciably from the rumen to the duodenum; however, the relative prOportion of this fraction to the total nitro- gen decreased due to the proteolytic activity of digestive secretions in the abomasum and duodenum. Ammonia nitrOgen made up a considerably greater share of the total nitrogen in the rumen than in either the abomasum or duodenum. Polypeptide nitrogen increased in.passing from the rumen to the duodenum with the ratio of polypeptide nitrOgen to total nitrOgen being greatest in the abomasum and minimal in the duodenum. Primary hitclysis 01 mi- Res 1: :zzz-azino Di 1: :21; 52812 eta“. Sufi-ed an a pzziies by d u ::. H‘ ‘z'hotle n1 '1 under“ 33'. I \g‘ Q ‘1'56) I 145 hydrolysis of protein appears to have taken place in the abo- masum. Residual nitrOgen, which was primarily in the form of mono-amino nitrOgen, was practically absent in the rumen and in only small quantities in the abomasum. This fraction con— stituted an appreciable portion of the total nitrogen in the duodenum thus indicating extensive degradation of the poly- peptides by digestive secretions in the proximal small intes- tine. Hogan (1957). by employing a re-entrant fistula either in the first part of the duodenum or in the terminal part of the ileum of sheep, calculated that about 64 percent of the digestible nitrogen was lost in the small intestine when a ration of hay and grain was fed. Similar results have been obtained with fistulated cows by Balch (1957) who used the lignin-ratio technique for determining the extent of digestion in the rumen and in the entire alimentary tract. Intestinal digestion was estimated by difference. Reviews specifically dealing with the digestion and metabolism of proteins and other nitrogenous compounds in the ruminant have been written by McNaught and Smith (1947), Reid (1953), Underwood and Meir (1953), Chalmers and Synge (1954), Hale (1956), Gallup (1956) and Moir (1957). 146 The lipid constituents Ether extract, which is an ill-defined fraction used in the routine proximate analysis as an expression of the lipid content of a feed, contains, in addition to lipids, plant pig- ments such as chlorOphyll, xanthOphyll and carotene, and traces of various other substances. In leafy materials, in fact, these latter substances may represent some 25 to 40 per- cent of the total ether extract fraction. Most feeds, with the exception of the oil meals, are relatively low in ether extractable substances. This is particularly true of forages and only about 30 percent of this fraction is true fat. The literature pertaining to the chemical composition of crude fat in roughage has been reviewed by Sullivan and Gerber (1947). An extensive amount of data relative to the ether extract content of cereal grains and forages has been compiled by Miller (1958) . Surprisingly little work has been done in mature ruminants with regard to the mechanisms involved in lipid digestion. This may be due, in part, to some of the complexities involved in studying fat digestion or due, in part, to the greater im- portance placed upon various other aspects of ruminant diges- tion. It is well established that the ether extract of feces consists of digestible fats which have escaped breakdown, lipids which are non-absorbable, such as some of the plant sterols, and non-lipid material of food origin such as plant s sf.‘ :‘1' 0.01 . 9-": II. at .s‘ V‘s ~l. 147 pigments. It is also recognized that the feces may contain metabolic fat of body origin. In Herbivora, fat digestion is still further complicated by the protective action of undigest- ed cellulose surrounding the fat thus serving as a barrier against digestive action in general, by the relatively greater intake of non-absorbable materials such as pigments and by the possible synthesis in the rumen of microbial lipids which may or may not be made available by digestive action in lower seg- ments of the tract. It is well known that diets rich in unsaturated lipids modify the depot fate of most animals to resemble the dietary fats, but ruminant depot fats are relatively unaffected (Brooker and Shorland, 1950; Shorland, 1950, 1953, 1955). According to Shorland (1958) this also holds for milk fats, at least as far as the long-chain unsaturated fatty acids are concerned. In addition, other peculiarities of ruminant fats, such as the presence of substantial amounts (5~lO%) of trans unsaturated acids and of mono- and di-unsaturated acids which differ from aisle and lenoleic acids in the position of their double bonds, have been demonstrated by Hartman g; a1. (1954, 1955) and by Shorland (1956), respectively. Shorland (1950, 1955) suggested that these differences in fatty acid composi- tion between the fats of ruminants and non-ruminants might be attributed to modification of the dietary fat in the rumen. Perhaps the first observation of the effect of the rumen l. \ 'zl' l in. o,~‘ 148 on dietary fat was made by Reiser (1951). He reported that when sheep rumen contents were incubated with a linseed oil emulsion hydrOgenation of linolenic acid took place. Similar results were reported by Hoflund at. _e__l_. (1956b) using fistu- lated sheep. The observation by Willey _e__t_ El. (1952) that the depot fats of steers fed on cottonseed oil contained more stearic acid than the controls led Reiser to suggest that the high 1 content of stearic acid in the depot fats of ruminants was due to the hydrogenation of dietary 618 unsaturated acids in the rumen. More recently considerable support for this suggestion has been obtained in a number of investigations. Shorland 23 pl. (1955) found the rumen contents of pasture-fed sheep con- tained stearic acid as the main lipid constituent whereas linolenic acid was the main component of pasture lipids. Furthermore, incubation of linolenic acid with sheep-rumen contents produced primarily stearic and not linoleic acid, as was originally reported by Reiser (1951). Subsequent studies by Shorland g3; ag. (1957), in which oleic, linoleic and lino- lenic acids were incubated with sheep-rumen contents, substan- tiate the earlier findings of Shorland gt g;. (1955) but indi- cate that hydrogenation of the unsaturated acids lg zitgg is much less complete. Reiser and Reddy (1956) fed cottonseed oil and linseed oil to goats and found that the linoleic and linolenic acids present were decreased to a very low level in 149 the rumen and increased amounts of saturated fatty acids were formed. Further support of hydrOgenation in the rumen is indicated by the studies of Hoflund at £1. (1955) who found that feeding unsaturated fat to young animals without an active rumen flora resulted in the storage of unsaturated fat in the depots. Garton and Oxford (1955) found the lipids extracted from rumen bacteria of hay-fed sheep were composed of phOSpholipids, neutral fat, lower fatty acids, unsaponifiable matter and steam-volatile neutral solid. The ”true" lipids amounted to 9 percent of the dry weight of the bacteria. No linoleic or linolenic acid was detected in the neutral fat or phospho- lipids. In recent investigations Garton g§,al. (1958) incubated triglycerides in the form of linseed oil and tung oil with the rumen contents of sheep in a manner similar to that described by Shorland g3 a1. (1957). They found that not only did hydro- genation occur but also that considerable lipolysis of the triglycerides had taken place. It was further shown that the lipolysis was the result of enzymatic action. Lipolysis of ingested triglycerides in the rumen of an intact sheep was found to be even more extensive than was previously seen in ig,zitgg experiments. Since these authors could observe no lipolytic activity in samples of adult sheep saliva they pre- sumed that microorganisms were responsible for the production 150 of a lipase in the rumen. Thus, on the basis of preliminary observations they concluded that, in the ruminant, dietary triglycerides reach the small intestine largely in the form of free fatty acids, of which the unsaturated components have been modified by hydrOgenation. This is in marked contrast to the digestion of lipids in adult non-ruminant animals in which little or no lipolysis occurs before triglycerides of the long-chain fatty acids reach the intestine. By sampling ingesta in close proximity of the reticulo- omasal orifice at frequent intervals in fistulated cows Balch (1957) obtained rumen digestion coefficients ranging from 10 to 57 percent for the ether extract fraction of various rations. Though the results suggest that some absorption of the products of fat digestion may take place prior to reaching the lower gut there is no conclusive evidence to indicate these substances are absorbed directly from the rumen. In fact, much of the available evidence indicates there is a con— siderable addition of ether extractible substances of non— dietary origin to ingesta in the rumen (Hale gg.gl., 1940, 1947; Chance g§.g;., 1953b; Rogerson, 1958). Both Hale gt .§l~ (1947) and Chance g; g;. (1955b), using a rumen evacuation_ technique with fistulated animals, found ether extract accu- mulated to a large extent during the first six hours after feeding but rapidly disappeared from the rumen during the sub- sequent six to eight hours. Hale gt g;. (1947) were of the 151 opinion that this initial increase was due to the synthesis of fats by the rumen microorganisms and that the decline which followed was due to rapid passage of the fats from the rumen to the lower tract. There appears to be general agreement that most of the ingested lipid, though modified and perhaps added into, reaches the small intestine where the glycerides and fatty acids under- go absorption. Furthermore, the data of Balch (1957) and ROgerson (1958) indicate a substantial addition of ether ex- tractive material in the lower gut. That this material is non-fat in character is suggested by the studies of Hale (1939) who found that true fat was often digested to a high degree even though there was a negative coefficient of digest- ibility for ether extract. Thus, it may be provisionally assumed that the absorption of glycerides and fatty acids in the ruminant takes place, for the most part, in the small in- testine in much the same manner as it does in non-ruminant animals. The ggorganic constituents Present evidence indicates that calcium, phosphorus, sodium, potassium, chlorine, magnesium, sulfur, iron, iodine, manganese, capper, zinc and cobalt perform essential functions in the body and must be present in the food. (Other elements such as boron, silicon, etc. are regularly found in the animal 152 body but, as yet, no essential function has been demonstrated for them. Natural foodstuffs consumed by ruminants normally contain all of the essential elements though considerable variation in their elemental composition may be encountered (Miller, 1958). In addition, sodium, potassium, phosphorus, calcium, magnesium and chlorine enter the rumen in substantial amounts via the saliva (McDougall, 1948; McGilliard, 1956). McGilliard has estimated that approximately 70 grams of salivary ash per day entered the rumen of a mature cow receiving alfalfa hay gg libitum. About 40 grams of this was sodium, potassium, phoss phorus, calcium and magnesium. Cobalt, copper and iodine have been detected qualitatively in saliva and may enter the rumen under some conditions (McGilliard, 1956; Allen, 1958). The importance of assessing the effects of salivary secretion in the interpretation of the results of metabolism and mineral balance studies has been emphasized by Franklin (1932). It has been generally recognized for many years that some of the absorbed minerals are excreted into the gut and elimin- .ated in the feces. As a result little importance has been attached to values for the digestibility of most of the min— eral elements. On the other hand exchange between the various segments of the gastrointestinal tract and the blood may be of considerable importance. This aspect has received, until re— cently, only limited attention and the significance of these 153 changes still remains subject to considerable speculation. According to Dukes (1955) the principle sites of exchange in the monogastric animal are the small and large intestine. These same segments appear to be of major importance in the ruminant but are not the only parts of the tract in which absorption and secretion occur. The eXperiments of Hale (1959), Boyne g3 g1. (1956), Regerson (1958) and Balch (1958) indicate that, in many instances, the amounts of ash lost by absorption from the stomach seem to be exceeded by the amounts added from an endOgenous source. In other instances net ab- sorption appears to have taken place. Sperber and Hyden (1952) round that chloride was absorbed against a concentration gradient from a rumen pouch of a goat. Similar observations have been reported by Sperber g3 gl, (1955) and Parthasarathy and Phillipson (1955) for sheep. Dobson and Phillipson (1958), from a summation of the forces exerted by the concentration gradient and the potential dif- ference, have concluded that chloride is a passive ion and that absorption against a concentration gradient is due to the potential difference. This does not appear to be the case with sodium. The experiments of Parthasarathy and Phillipson (1953) indicate that sodium was absorbed from the rumen but no evi- dence was obtained of absorption against a concentration gradi- ent. In a later series of experiments Dobson (1955) found that sodium was actively absorbed in appreciable amounts. 154 Phillipson and Cuthbertson (1956) suggest that the rumen epithelium possesses a mechanism similar to that of the kidney tubule whereby sodium is transferred from the rumen to the plasma. There seems to be no evidence to indicate that potas- sium acts any differently than a passive ion. Sperber and Hyden (1952) observed that potassium was absorbed from a rumen pouch of a goat when its concentration exceeded that in the blood and that passage in the reverse direction occurred when its concentration was lower than that of the blood. This has been confirmed in sheep by Parthasarathy and Phillipson (1955). Sperber and Hyden (1952) were unable to detect the pas- sage of inorganic phOSphorus through the rumen epithelium by the usual chemical methods. By using P:52 however, Scarisbrick and Ewer (1951) and Parthasarathy gt gt. (1952) were able to demonstrate that the epithelial membrane is permeable to in- organic phosphorus. Garton (1951) found that concentrations of inorganic phosphorus in the rumen were five to ten times greater than they were in the plasma. According to Scarisbrick and Ewer (1951) and Singleton (1955) little, if any, phos- phorus absorption occurs from the rumen in spite of the con- centration gradient and potential difference favoring absorp- tion. Smith gt gt, (1955) were of the Opinion that the trans- port of inorganic phosphorus into the rumen via the rumen epithelium does occur in sheep. On the other hand Smith gt a1. (1956) concluded that most of the phosphorus entering the 155 bovine rumen seemed to enter in the saliva. Information on the secretion or absorption of other min- eral elements into or from the rumen appears to be even more limited. Neither cobalt (Keener gt g;., 1951; Comer and Davis, 1947) nor capper (Comar gt gt., 1948) has been found to be secreted to any large extent into the rumen. Hansard _t gt. (1952) observed that intravenously administered radio-calcium appeared in the rumen but attributed its source to saliva. Garton (1951) indicated that the calcium values for the rumen liquor of hay-fed sheep were higher than those reported for saliva but was able to account for the excess calcium by simple solution of this ion from the food. Results for mag- nesium similar to those for calcium have been reported by Garton (1951). Stewart and Meodie (1956) found that absorp- tion of magnesium took place from the rumen after administra- tion of heavy doses of magnesium sulphate into this organ. Whether absorption occurs at normal rumen magnesium levels is not known. Because of its inaccessible position and complicated structure less is known of ion exchange in the omasum than is known for other parts of the tract. Heretofore the primary method used to study this organ has been the slaughter tech- nique. More promising fistula techniques have been recently developed by Bouchaert and Oyaert (1954) and Best (1957). Ekman and Sperber (1952) have presented data which strongly 156 suggests that bicarbonate is absorbed to a considerable extent and that chloride is secreted into the omasum. Evidence that calcium, magnesium and inorganic phosphorus are concentrated in the omasum has been obtained by Garton (1951); concentra- tion of calcium has been substantiated by Hansard gt al- (1952) using isotopic Ca45. In two out of three sheep Parthasarathy and Phillipson (1955) showed a large decrease in the concentrations of sodium and potassium in the contents of the omasum as compared to the rumen contents. Regular losses of sodium in food passing through the omasum of sheep have been found by Oyaert (1955). If one considers the sim- ilarity of the epithelium of the omasum as compared to the rumen it seems likely that it has the same prOperties. There is very little information in the literature on the inorganic composition of gastric Juice in ruminants. It has been provisionally assumed to be similar in composition to that of simple—stomached animals. According to Babkin (1950) pure gastric Juice of the dog contains primarily chlorides with sodium, potassium, calcium, magnesium and phosphorus being present in small amounts. Hill (1955) found gastric secretion in goats and sheep to be continuous. Sperber gt_gt. (1956), assuming gastric Juice was not stronger than 0.1 N HCl calculated that 1.5 to 2 parts of gastric Juice would be re? quired to acidify one part of rumen or omasal.contents to pH 5.0. This ratio is similar to that proposed by Masson and J 157 Phillipson (1952) who calculated that 2 parts of gastric Juice would have to be added to 1 part of omasal contents to produce the chloride concentration present in the abomasum of sheep. If this is, in actuality, the case then a substantial addition of inorganic material would occur to the ingesta at this point. There seems little reason to believe that inorganic salts are ordinarily absorbed from the abomasum in significant quantities (Dukes,.1955). The role of the intestinal tract in the absorption of minerals has been amply demonstrated by Boyne gt gt. (1956) and Rogerson (1958) with sheep and by Balch (1959) with cattle. Evidence that the small intestine acts as a secretory site for calcium and phosphorus has been obtained by Hansard 21.21- (1952) and Smith gt gt. (1955, 1956), reapectively. In addi- tion, inorganic salts enter the intestinal tract in the bile and pancreatic secretions (Babkin, 1950). According to Dukes (1955) the elements of endOgenous origin are, for the most . part, reabsorbed by the time they reach the terminal colon. As a result of the continuous secretion and reabsorption of elements throughout the alimentary tract values for the digestibility of ash in the various segments are obviously only balances and give no reliable indication of the extent to which these processes occur. 158 Summary The stomach of the domestic ruminant does not differ in its early developmental form from the simple stomach of other mammals. At birth four compartments of the stomach are present; the abomasum is the largest but the reticulo-rumen and omasum rapidly develOp. This deveIOpment corresponds to the transition from a milk to a dry-feed diet. Bulk (roughage) appears to be responsible for increasing the capacity whereas chemical entities seem to serve as a stimulus for promoting papillary growth and tissue deposition. Final relative size and position may be attained as early as 3 months of age but actual maturity (capacity, etc.) may not be reached until approximately one year later. The pathway followed by various food materials as they pass through the stomach varies considerably and is influ- enced by the nature of the food material itself.' Water and dissolved substances pass from the reticulo-rumen at a faster rate than solid ingesta and meals leave more rapidly than do long forages. Rumination, by reducing particle size, may in- crease the surface of feeds to microbial attack and so hasten passage from the reticulo-rumen. The course followed by solids and liquids through the omasum still remains a matter of conJecture. The factors which effect separation in the abomasum and lower gut are much the same as those which Oper- ate more dramatically in the reticulo-rumen. 159 The delay in passage of food residues through the alimen- tary tract of ruminants is due primarily to retention in the reticulo-rumen. Passage is characteristically represented by a sigmoid—shaped excretion curve. Approximately 50 per cent of a ration of long hay disappears from the rumen of cattle in 24 hours while about 80 percent is cleared in 48 hours. Pas- sage in sheep and goats is slightly more rapid than in cattle. Food residues spend approximately 70 percent of their time in the reticulo-rumen and 30 percent in the remainder of the gut. The quantity5 quality and physical state of the food ingested markedly influences its rate of passage through the alimentary tract. Only limited evidence is available concerning the mechan- ics and regulation of the passage of ingesta through the rumi- nant stomach. It is generally agreed that the coordinated action of the first three stomach compartments is intimately involved in the transfer of ingesta between the rumen and reticulum and from the reticulum to the omasum. Activity of the reticulo-omasal orifice seems likely to be of consider— able importance in regulating passage. Forestomach motility is markedly increased during eating and during increased intra- ruminal pressure. Reticular activity is reduced during_rumin- ation and distension of the abomasum. Movements of the fore- stomach do not appear to be directly influenced by intestinal reflexes. The mechanisms regulating passage through the 160 abomasum and lower gut of ruminants are provisionally assumed to be the same as those which function in other species. Quantitation of digestion in the various segments of the alimentary tract of ruminants is considerably more difficult than estimation of the extent of digestion for the tract as a whole. A number of new methods have recently been devised for this purpose. Ingesta in the reticulo-rumen accounts for approximately two-thirds of the total contents in the alimen- tary tract. The weight and dry matter content of ingesta in the reticulo-rumen at any given time varies only slightly, despite large variations in the level of feeding. The quantity of water and dry matter decrease markedly with time after feed-‘ ing. Recent estimates of water balance indicate the amount of water entering and leaving the reticulo-rumen in 24 hours is rather appreciable. The amount of dry matter leaving the rumen each day is equivalent to the amount taken in, providing the animal is maintained on a constant ration for a suitable period of time. Some 25-75 percent of the dietary dry matter may be digested in the rumen. As the amount of concentrate in the diet increases the amount of dry matter digested in the rumen tends to increase. Ingesta in the omasum is more dehydrated than that found in either the reticulo-rumen or the abomasum. Approximately 50 percent of the water entering the omasum may be absorbed. hosses of dry matter in the omasum are due to the absorption 161 of soluble products resulting primarily from fermentation in the reticulo—rumen. Secretion of gastric juice in ruminants is relatively continuous. Omasal ingesta is diluted about 2 to l by gastric juice in the abomasum. Little, if any, absorption occurs from this organ. The dry matter may increase to some extent due to the addition of nitrogenous materials and soluble ash. Further additions of dry matter occur in the proximal part of the duodenum. By the time the cecum is reached, however, absorption of almost all of the digestible nutrients has taken place. The digestibility of dry matter in the intestinal tract may range from 0-55 percent and tends to increase as the digestibility decreases in the reticulo-rumen. Dry matter losses in the colon are negligible with the exception of sol- uble ash. Some degree of dehydration takes place throughout the intestinal tract but the bulk of the water is removed from the ingesta in the terminal section of the colon. Complex and simple carbohydrates are readily fermented to volatile and non-volatile fatty acids by the microorganisms in the reticulo—rumen. The total concentrations and quantities of individual acids present are dependent on the diet. Acetic acid predominates under most conditions, but substantial amounts of propionic and butyric acids are always formed. Higher volatile acids may be produced by condensation of the short-chain acids. High starch or sugar diets favor propionic acid production and, in general, foodstuffs which are rapidly .fermented in the rumen give rise to less acetic acid. 162 Cellulose is readily degraded to the short-chain fatty acids, succinic and lactic acid, and various rumen gases by cellulolytic bacteria in the rumen. Available evidence indi- cates that a multiple enzyme system is involved in the hydrol- ysis of native cellulose, and that the enzyme responsible for the initial attack on cellulose is more labile than those which hydrolyze partially degraded cellulose. The role of protozoa in cellulose digestion is less clear. Although some species do contribute to cellulose digestion, their activity is not essential for the adequate utilization of cellulose in the rumen. The extent of cellulose degradation in the rumen has been found to range from about 50 to 60 percent, depending on the type of forage fed. Extensive digestion of the dietary pentosans occurs in the rumen. Pentosanase activity is associated with the par- ticulate matter since bacteria-free rumen contents are devoid of activity. Acetic, propionic and butyric acids are the end products of fermentation, with acetic acid predominating. Fermentation of the pentosans does not appear to follow the same pathway as that followed in the fermentation of cellulose. Pectin and pectic acid is digested in sheep to the extent of about 75-90 percent. No information is available as to the end products or the mechanisms of breakdown involved. Lignin, which is a carbohydrate only by association, is degraded in the rumen to a variable extent depending upon the ..‘". 1;. a s- 'u 163 kind and stage of maturity of the forage with which it is associated. Most evidence indicates the digestibility of lignin in the rumen is negligible and suggests that any diges- tion which does occur takes place posterior to this part of the tract. Starch is readily fermented in the rumen with the produc- tion of both volatile and non—volatile fatty acids. There are numerous bacteria, as well as protozoa, which possess amylolytic activity. Several extracellular starch-splitting enzymes have been found in bacteria and protozoa-free rumen fluid. When rations high in starch are fed to ruminants, lactic acid accumulates in the rumen and the prOportion of prOpionic acid is higher than is usually found. The extent of starch degradation in the rumen may be as high as 90—100 percent of that ingested. Simple sugars and other intermediates in carbohydrate breakdown are actively fermented by a wide variety of both the bacteria and the protozoa of the rumen to yield substan— tial amounts of acetic, propionic and butyric acids. In- creased levels of prOpionic acid are observed when readily fermentable carbohydrate is added to the rumen. It is prob- able that most of the rumen propionate arises by lactate fer- mentation and/or decarboxylation of succinate. Polysaccharide storage within the cytoplasm is a charac- teristic of a large number of organisms associated with carbo- 164 hydrate fermentation in the rumen. The protozoa are particu- larly active in this respect. The reserve polysaccharide stored by the holotrich ciliates has been shown to be an amylo- pectin. Reserve starch storage does not seem to be a major mechanism by which carbohydrates are supplied to the host but it does assume a significant role as a reserve source of energy for the organisms during periods when carbohydrates are not readily available. Acetic, butyric and lactic acids are the principle products of endogenous fermentation. The relative prOportions and the quantities of volatile fatty acids produced in the rumen varies widely depending on the ration fed. The concentration of total volatile acids in the rumen increases after feeding for 9 to 6 hours. Rations high in concentrates promote the greatest range and most rapid change in concentration of the volatile fatty acids. The relative preportion of acids higher than butyric increases with the amount of concentrates and/or protein fed. The pro— portions of acetic and propionic acids appear to vary inverse- ly. High concentrate-low hay diets or mixed diets, in which the hay is finely ground, decrease the ratio of acetic to pro- pionic acid. Lactic acid is found in the rumen in appreciable amounts only when rations high in starchy concentrates are fed. Short-chain fatty acids are readily absorbed from the reticulo-rumen, omasum and intestine into the bloodstream. The rates at which volatile acids are absorbed from the rumen vary with the pH of the contents. Absorption rates at pH 165 values below 6.5 are considerably more rapid than those above 7.0-7.5. Absorption of the individual acids, like that of the total volatile acids, appears to be a reflection of their concentration in the rumen. Absorption from the reticulo- rumen and omasum is extensive for only limited amounts of the volatile acids are found in the abomasum. Estimates of digestibility of the carbohydrate fraction of diets of widely different types indicate that 40-80 percent of the N-free extract and 0-60 percent of the crude fiber may be broken down in the reticulo-rumen. Diets rich in concen- trates are digested to a greater extent in the rumen than those consisting mainly or entirely of roughage. Introduction of increasing amounts of concentrates in the diet tends to depress the digestibility of crude fiber in the rumen but the preportion of crude fiber digested elsewhere in the gut is raised. NitrOgen entering the reticulo-rumen is derived from the diet, from saliva and, under certain conditions, from its pas- sage through the rumen wall from the blood. The latter sources are important under conditions where the dietary in- take of nitrogen is low. Rumen contents are strongly pro- teolytic. The nature of the protein is an important factor in its rate of hydrolysis. Losses of nitrogen from the rumen are related to the rapidity with which the protein is hydro- lyzed. There is no evidence of any extracellular proteolytic 166 activity in rumen contents. Protein is degraded by the action of proteolytic enzymes of the microorganisms. Peptides and amino acids are produced and these in turn are either assim- ilated by the rumen organisms or deaminated with the produc- tion of ammonia, carbon dioxide and volatile fatty acids. The branched-chain fatty acids arise chiefly as end-products of amino acid metabolism. Other non-protein nitrogen’com— pounds such as urea, nitrate, nitrite, etc. are deaminated or reduced to form ammonia. Appreciable concentrations of ammonia may occur in the rumen after feeding. Inclusion of starch in the diet markedly reduces the concentration of ammonia. Under high rumen- ammonia production ammonia may pass in quantity from the rumen to the small intestine. Ammonia absorption from the rumen and small intestine is extremely rapid. The absorbed ammonia is metabolized by the liver to urea, which may be ex- creted in the urine or recycled to the rumen. It has been repeatedly demonstrated that rumen micro- organisms synthesize their body protein from simple nitrogen components and that synthesis is greatly enhanced by the presence of starch in the diet. To what extent these organisms use extracellular ammonia, free amino acids or peptides as their source of nitrogen is not well known. It has been shown that rumen organisms possess the ability to synthesize an ample supply of amino acids for the host with diets in which 167 urea is practically the sole source of nitrogen. Recent esti- mates indicate the conversion of food protein to microbial protein in the rumen is also appreciable, particularly with the more readily hydrolyzable proteins. Much of the protein‘ passed from the rumen and digested in the abomasum and small intestine is contributed by the bodies of the bacteria and protozoa. Both bacterial and protozoal proteins are of reason- ably high biological value. The concentration of nitrogen in the ingesta is increased at each successive level of the tract (reticulo-rumen, omasum, abomasum, duodenum). This is due in part to absorption of the non—nitrogenous constituents and in part to the addition of nitrogen from secretions and/or desquamated epithelium. A considerable addition of endogenous nitrogen occurs in the abomasum and the small intestine. Nitrogen concentrations are greatest in the proximal duodenum and diminish distally. Digestible nitrogen has been removed, for the most part, prior to reaching the cecum. The relative proportions of protein nitrOgen and ammonia nitrOgen to total nitrogen are greatest in the rumen and least in the small intestine. Primary hydrolysis of the pro- teins passing from the rumen result in increased polypeptide nitrOgen to total nitrogen ratios in the abomasum. Alpha- amino nitrogen concentrations are greatest in the proximal duodenum. The principle site of absorption of nitrogen is the 168 proximal small intestine. Although ruminants and non-ruminants may have the same dietary intake of lipids there are distinct differences in their metabolism of the lipids. These differences are attri- butable at least in part to differences in the anatomy and physiolOgy of their digestive tracts. Recent evidence indi- cates dietary glycerides can be hydrolyzed and unsaturated fatty acids can be hydrOgenated and otherwise modified by the formation of geometrical and pesitional isomers. Both lipo- lysis and hydrogenation appear to be due to microbial activity in the rumen. The glycerol, derived from glyceride hydrolysis, is fermented almost entirely to propionic acid in the rumen. There is no evidence available indicating the long-chain acids are absorbed from the reticulo-rumen, omasum or abo- masum. Dietary glycerides in the ruminant reach the small intestine largely in the form of free fatty acids. The prin- ciple site of absorption is the small intestine. The addition of a substantial amount of lipid material to the ingesta may take place in the rumen. From available evidence it does not seem likely that it is synthesized by the rumen organisms. Desquamation of the rumen epithelium (stratum corneum) may account for a major portion of the endo- genous lipid (mainly triglyceride). A substantial addition of ether extractive material likewise occurs in the lower gut, ‘however, this material is apparently non-fat in character. 169 The exchange of inorganic ions and water between the in- gesta and the blood must be considered in relation to the min~ eral balance of the whole animal. Ingested minerals, if solu- ble, are absorbed from the digestive tract and amounts in ex- cess of requirements are excreted. Natural feedstuffs con- sumed by ruminants contain most of the essential elements in quantity. Saliva of the ruminant is a major factor in the maintenance of both the fluid volume and the inorganic compo— sition of rumen contents. The ionic composition of saliva is controlled in relation to the electrolyte balance of the ani- mal. Reasonable constancy of ionic composition of rumen fluid is maintained by the rapid absorption of inorganic ions and by the passage of water from blood to rumen contents when the osmotic pressure of rumen fluid exceeds a certain value. The reverse process occurs if the osmotic pressure in the rumen is lower than this value. Chloride is passively absorbed from the rumen due to the potential difference between the blood and rumen fluid, and there is no evidence to indicate that potassium acts any dif- ferently than a passive ion. On the other hand, sodium is actively absorbed against a concentration gradient; the cellu- lar mechanisms involved are unknown. Permeability of the rumen epithelium to other inorganic ions (P, Ca, Mg, Co, Cu) appears to be rather limited. These ions are primarily of dietary or salivary origin. Exchange in the omasum appears to 170 be similar to that in the rumen. Further additions of the elements occur in the abomasum and small intestine. Both the elements of endOgenous origin and the soluble elements of dietary origin are absorbed, for the most part, by the time they reach the terminal colon. The literature pertaining to the role of the ruminant stomach in physiologic and metabolic processes is so extensive that this review is admittedly incomplete. Indulgence is begged for the fact that many papers have been either omitted from the review, inadequately discussed, or perhaps misinter- preted. 171 PRELIMINARY EXPERIMENT Experimental Procedure The objective of this preliminary study was 1) to develOp a technique for the establishment of a re-entrant duodenal fistula in the bovine, 2) to determine what effect, if any, the fistula might have on the functional processes of the animal and 3) to develop a satisfactory method for contin- uously and quantitatively sampling ingesta from the digestive tract of the animal without perceptibly upsetting normal physiOIOgic relationships. Establishment of re-entrant duodenal fistulg U-tube Plexiglass tubing (1/2 inch inside diameter, 9/16 inch outside diameter) was used in making the connecting U—tube. The procedure for bending the tubing consisted of (a) passing a short length of one-half inch woven clothesline rcpe through the center of the tubing to prevent collapse of the walls during the heating and bending process, (b) heating the tubing under infra-red heat lamps until rubbery in consis- tency and (c) bending the tubing on a previously constructed U-shaped form of the desired dimensions beforeallowing it to cool. Flexible plastic couplings (1/2 inch inside diameter, 9/16 inch outside diameter ”Tygon' tubing) were attached, fol- lowing removal of the rcpe, by sliding a short section of the 172 flexible tubing onto each arm of the U-tube and by wrapping each union tightly with 40 pound test nylon fishline. Cannulae Each cannula was constructed from surgical stainless steel. The stem (2 and 3/8 inches long, 3/8 inch inside diameter, 1/2 inch outside diameter) was threaded with standard machine threads (20 threads per inch) to within one inch of the flange. Approximately one-third of a 2-1/4 inch- section of tubing (1/2 inch inside diameter, 3/4 inch outside diameter) was milled Off to make the U-shaped flange. The resulting edges were spread, rounded and polished. A 1/2 inch hole was drilled medially to receive the stem. The flange and stem were subsequently silver-soldered to form the T-shaped cannula illustrated in Figure 3. The external collar, which was made from l/E inch plexi- glass, was 2-5/8 inches in diameter. It was drilled and tapped to fit the stem and knurled to facilitate manipulation. Surgery The subject for the re-entrant fistula was an eight-month old Holstein steer weighing approximately 500 pounds. NO special pre-Operative treatment was given but the steer was not fed on the morning of the Operation. The skin over the Operative area was prepared by clipping as closely as possible, washing thoroughly with bactericidal soap and water and sterilizing with 70 percent alcohol. Usual aseptic methods were used throughout the surgical procedure. The Operation was performed with the patient in lateral 1'73 Figure 3. Design of duodenal cannula and external collar 175 1 anesthesia. recumbency under the influence of Surital Sodium Each gram of Surital Sodium was dissolved in 30 ml. of sterile distilled water and given intravenously to desired effect. Maintenance injections were given as needed. A total of three grams of Surital Sodium were used throughout the course Of the three and one-half hour Operation. Operative technique was in part patterned after the method described by Crocker and Markowitz (1954) for the ass tablishment Of an intestinal fistula in the dOg.v Internally the fistula was placed five inches from the pylorus, orad to the sites where the bile and pancreatic ducts enter the duo- denum (Figure 4). All of the ingesta leaving the abomasum flowed to the upper segment of the duodenum through an ex- teriorized plastic U-tube which could be conveniently removed for making collections (Figure 5). Externally the fistula was located in the right abdominal wall between the eleventh and twelfth ribs at approximately the level Of the costo-chondral junction. It was necessary to resect the last rib and remove the lower half along with its corresponding costal cartilage in order to make the dc- sired portion of duodenum more accessible. Entrance to the _abdominal cavity was through the incision used in the rib re- section.» The two stab incisions for the cannulas were made 1Parke-Davis CO., Detroit, Michigan. 176 pomp» unannosdam ca maapmau ucmnpcotoa uo coapamom opapmaem .w madman 177 tau. «$0 5.3% (EQQV (4:356 2:4:kaut 52>wuwt ‘ . .. C l -i e in y ,. 1‘- ' . I I \ e i . I . ...( .II \ .// 2‘3:ch . ...... . QNQQVNQ .:<0 tbihfiObQ kan him “(NQUIVQ kubc ka (Nth? (Q 178 33 .3. enspub spas masumdu pcmapaoiea no codpmooa Hespepxm .o ensmda 180 through the abdominal wall about two inches cranial to this laparotomy incision. The duodenum was transected five inches from the pylorus. Both stumps were closed by the Parker-Kerr (1908) method of oversewing a clamp, followed by additional interrupted sutures (Lembert). A stainless steel cannula was placed into each duodenal stump by way of a three inch longitudinal incision made two inches from the blind end. Following insertion of the cannulas, the incised duodenum was closed with interrupted Lembert sutures. A purse string suture was used around the [protruding tubes to invert the edges of the exposed mucosa. Portions of adjacent omentum were then draped over each can- nulated stump and'sutured in place so as to cover suture lines. The cannulas were exteriorized by inserting a short, sharp trocar through the abdominal wall. This trocar had a bore slightly larger than the bore of either cannula with the exception of its base which just fitted into the lumen of each cannula. Small skin incisions were used to facilitate passage of the trocar and cannulas through the abdominal wall. Each cannula was held in place externally by a plexiglass collar. Daily adjustments of the collar were necessary until the local swelling, resulting from the Operative manipulations,had re- ceded. The eXposed ends of the cannulas which protruded one and one-half inches and which were four inches apart were connected 181 by a clear plexiglass U-tube with flexible plastic couplings. These couplings were slipped over the ends of the cannulas and secured there by radiator hose-type clamps. Post-operative care consisted of an immediate intravenous injection of one liter of 5 percent dextrose in physiolcgical saline. This injection was repeated in four hours. Daily intramuscular injections of penicillin and dihydrostreptomycin were given for five days. Ratipns and feeding procedure The steer received a ration consisting of 70 percent second-cutting alfalfa hay and 30 percent ground corn during the period in which pre- and post-surgical digestion trials were conducted. First-cutting alfalfa hay, which had been cut in the prebud stage and run through a field crusher, and a finely ground corn-mineral mix were fed in the same prOpor— tions during subsequent duodenal collection trials. The steer was fed the total ration of three pounds of corn and seven pounds of hay once daily. Nine a.m. was desig- nated as O-hour feeding time. Water was available in a drink- ing cup and was metered on those days when the animal was in the metabolism stall. Pre- and goat-surgical digestion trigla In an attempt to determine what effect the re-entrant duodenal fistula might have on the digestive functions of the 182 animal pre- and post-surgical digestion trials were conducted. Each trial consisted of a 14 day preliminary period followed by a seven day collection period.’ The pre-surgical trial was conducted during the 21 day period immediately preceding sur4 gery; the post-surgical trial was conducted one month follow- ing establishment Of the fistula. Samples of hay and corn were taken daily during the digestion trials and composited at the termination of the experiment. Feces and urine were collected separately by means of a metabolism stall. Daily samples Of each were composited and subsampled at the end of each trial. All daily samples were kept refrigerated; final samples were frozen and stored at -20° C. until they were processed for chemical analysis. Duodenal trials Mgtgboligg stgl; The metabolism stall described by Nelson and his associates (1954) was further modified to in- clude special apparatus for the continuous collection and re- introduction of ingesta from the stomach into the lower gut. Mbdifications of the stall include: 1) construction of a frame and channel in the right-rear center section of the stall for installation of a moveable carriage and 2) con- struction of a moveable counterweighted carriage for holding the collection and re-introduction apparatus. Construction details are shown in Figure 6; detail figures one through six 183 Figure 6. Construction modifications (right side elevation) of collection stall 184 g" 'i.‘ 5' zeaIEAdves ANQE IRON 4" CENTERS I" HOLE WEIGHTS 7. l4—a RIGHT SIDE ELEVATION 185 are shown in Figure 7. The frame, which was braced with pipe, was welded in place following removal of the right-rear, mid section of the stall. Channels for the carriage were secured to the frame with machine screws so that adjustments in clearance could be made if necessary. Sheave brackets were welded to the tOp of each frame at a 45° angle. The aluminum carriage was assembled with one-quarter inch socket-head cap screws, inserted into the channels and counter- balanced with lead weights. Allen screws were used to lock the brass motor-support rod in place. Stainless steel collec- tion-tube hangers were fastened to the carriage frame with hinges thus allowing some flexibility of movement to the col- lection tube. The design of the equipment permits rapid adjustments in the position of the carriage to be made in response to changes in position of the animal.) Collection andgre-introduction apparatgg Construction details of the plexiglass collection tube and re-introduction tube are shown in detail digures seven and eight, Figure 8. I Two collection tubes were made to provide for interchange between periods during the collection procedure. Each was calibrated in 100 ml. divisions, with 10 ml. sub-divisions, and fitted with ears for insertion into the collection-tube hanger of the carriage (Figure 9). 186 haneemmm Mooa owmanamo “my mamas ens» coapospoapcdaea cowcam “my sumac phoneme ens» :oaposooapcanem my ucOEpmSncm soapm>eae pop paoaasm none: an Hocnmno owwannmo “my poxowup one weanmon noHHom “Hy mco«pmoamaoos Hampm coapooaaoo no moaswau Haepon .b mazwah 187 A9 959.... ..n L _ RNL w 0. m Macon gab...“- a, a F .3. mm Ila: a .. _lm _ E 2.8.... _ E 7\)\ N\_ k -r 3 14:2,. r4 .2 $56.... a __ .3 manor. 4: £TI|| ..«m [H L N -TITTTMWIIL 4 h j _ITIL ..IL N\. w. .NV manor. .2. wmaoi L1 2 war ...... .. a... _ _ 5.1..th WM” _rn I IU. IIIIII L. Alrlr - T a he _ , v e... @2543“ _HeiL fl...— Ink: 33.46.. . .. ..- \ \FIII a.m.—IL \\ t , \ , 188 Figure 8. Construction details Of plexiglass collection tube and re-introduction tube (7; Collection tube (8 Re-introduction tube COLLECTION TUBE FIGURE ( 7) 189 24" FIGURE (8) I. [.5 4.1. ;.+-«“.------—.;----1 I II 'I I I n —————— .u I I II II I | —————— —H I I :: II I I ;+ ------ II I I I: II : I n —————— f: I I II II I I II II I I rr ------ .-. I I II n I I II —————— ~ : I II H : ------- «:4 I : II .: : 0' fi— ————— 44‘ ”I I z: I: I I IT ““““ I I I I II II : I n ——————— II I I II II I I II ------- II ' I u___-__-.II I : .. I: . I II ________ u ' I II II : I II _______ .I.‘ I ' II II I I II II I I H _______ H I : II .. , I II _______ I: I I II M I I II ....... LI I I II II I U _______ II I II I! I Imf-II : _1— |_ {.r..-u- ,J 2: Lat—I ~—-5"D. II RE - INTRODUCTION TUBE 190 Figure 9. Collection tube mounted in hangar Of carriage 192 The re-introduction tube consists of two units: 1) an inner cylinder for re-introducing ingesta into the lower gut and 2) an outer water jacket for maintaining the ingesta at constant temperature. The inner cylinder was calibrated in 50 ml. divisions prior to its assemblage within the water jacket. A restricted Outlet was provided in the bottom of the cylinder and a short length of "Tygon" tubing of the same inner diameter was secured to this outlet. The length of the flexible tubing was subsequently adjusted to the desired length with the animal i3 gitg. Complete assembly of the re-introduction and collection apparatus is shown in Figure 10. Introduction of ingesta into the inner cylinder was facilitated by use of a funnel and tubing clamped to the car- riage frame (Figure 11). Agitation of ingesta within the inner cylinder was accomplished by means of a small electric stirring motor fastened to the motor support rod. Outflow from the cylinder to the lower gut was manually regulated by spring blade forceps. Union of the flexible tubing from the re-introduction tube to the lower gut cannula and from the stomach cannula to the collection tube was accomplished with radiator—hose clamps (Figures 12, 15). Rubber tubing was used to attach the inlet of the water jacket to a centrifugal immersion pump and to provide for re- turn flow from the water jacket to a constant temperature water bath. In addition to the water bath used as a source of 195 Figure 10. Complete assembly of collection and re-introduction ' apparatus 195 Figure 11. Re-introduction tube mounted in carriage with funnel and stirring motor 15 situ 197 Figure 12. Collection and re-introduction apparatus connected to duodenal cannulas \ I I I I I I I I 199 Figure 1:5. Position Of apparatus with animal at rest 201 heat to the water jacket of the re-introduction tube a second water bath was utilized as a heat source for an ingesta hold- ing vat. This vat was employed to maintain the ingesta, after collection and sampling, at constant temperature for subse- quent re-introduction into the lower gut. COllection and sampling procedure Three methods of collection were employed in an attempt to establish a tech- nique physiologically suitable for continuously measuring and sampling ingesta passing from the stomach. Method I. - none Of the collected ingesta was re-introduced into the lower digestive tract. Method II. - all of the ingesta Obtained dur- ing each fifteen minute period was re-introduced into the lower tract at the end of the period. Method III. - ingesta was continuously re-introduced into the lower tract at approxi- mately the same rate as it was collected. The collections were conducted in sequence with a minimum interval between trials of one week and were subsequently repeated in the same order. No collections were made on the animal if the U-tube became plugged within two days preceding the day of collection. The fistula animal was placed in the collection stall approximately one hour preceding the initiation of each col- lection to allow the animal to become accustomed to the equip- ment. All collections commenced with feeding, designated as O-hour, and were of six hours duration. Fifteen minutes before O-hour the U-tube was removed and connection Of the cannulas to 202 to the collection and re-introduction apparatus was estab- lished. The quantity of ingesta collected during this pre- liminary period_was recorded but the ingesta was not included in the first hourly composite sample. Sampling periods were arbitrarily established at 15 min- ute intervals and small samples were taken for each 15 minute collection period. The remaining ingesta for each four con— secutive periods was then composited to form an hourly sample from which a one liter subsample was obtained. All samples were immediately frozen and stored at -20° C. until they were processed for chemical analysis. The ingesta which was not taken as sample was maintained at body temperature for re-introduction into the lower diges- tive tract. All ingesta taken as sample was replaced with an equal volume of warm Ringer's solution acidified to pH 2.0. In addition to the samples of duodenal ingesta, samples of hay, corn-mineral mix, feces and urine were taken for each collection. These samples were likewise frozen and stored at ~20°C. until they were processed for chemical analysis. Data recorded during each collection consisted of the change in weight of the animal, the volume and pH of the in- gesta, the time and duration of eating, the time spent rumin- ating and the periods in which rumination occurred, water intake, the weight of feces excreted and the volume of urine voided. Ingesta volume and pH data were obtained for each 15 minute collection period. All other data were recorded for 205 the respective period of occurence or for the entire 6-hour collection. Chemicalganalyseg Preceding analysis the frozen samples were allowed to thaw at room temperature. Analyses for moisture, dry matter, organic matter and ash were made on the freshly thawed mate- rial. The hourly ingesta samples and the feces samples then were dried in pyrex pie plates in a forced hot-air oven at 60° C. The dried samples were ground in a Wiley mill to pass a 20-mesh sieve and stored in brown glass bottles until ana- lyzed. Standard A.O.A.C. methods of analysis (1957) were used to determine moisture, dry matter, organic matter and ash for the feed, feces, lS-minute and hourly ingesta samples. In addition, analyses for protein, crude fiber, ether extract and nitrogen free extract were made on the feed, hourly in- gesta samples and feces. The pH of the duodenal ingesta.was determined at the time of collection by means of a Beckman pH meter. NO analyses were made on the urine samples. Results The eXpegimental animal Surgical establishment of the re-entrant duodenal fistula proceeded without difficulty and post-surgical recovery of the 204 animal was uneventful. Flow of ingesta through the exterior- ized U-tube became evident soon after the steer recovered from the general anesthetic. Initially the cannulas were connected by a U-shaped piece of glass tubing. Because of breakage and difficulty in getting the rubber couplings to stay on, the glass tube was later replaced by a clear plexiglass tube with flexible plastic couplings. Blockage of the U-tube was occa- sionally experienced, especially if whole corn was present in the ration. In several instances large amounts of sand which passed from the stomach completely blocked the U-tube. Sand was invariably present to some extent in the ingesta. Block- age was readily alleviated by removing the U-tube and flushing it out with water. NO apparent deleterious effects resulted if relatively frequent checks were made on the animal so that the U-tube did not remain blocked for any prolonged period of time. The animal remained in excellent health throughout the experiment (Figure 14) and made a weight gain of over 500 pounds during the span Of a year and one-half even though the ration was fed at approximately the maintenance level. Effect Of fistulation on total digestion Analyses Of the feed and feces for the pre- and post- surgical digestion trials are given in Table l. The coeffi- cients of total digestion for the pre- and post-surgical digestion trials are presented in Table 2. 205 mazamam on» go pcoezmaancpme gouge new» mac zaoumsaxoaaam stacm HcpceEaaonxm .wa ouswah 207 Table 1. Chemical composition of feed and feces for pre- and post-surgical digestion trials Dry Organic Protein Ether Crude N—free matter matter (Nx6.25) extract fiber extract Ash 5 % % % z % % Alfalfa hay 87.6 92.9 19.8 1.8 31.0 40.3 7.1 Ground corn 87.8 97.9 11.3 4.6 2.3 79.8 2.0 Pro—surgical feces 20.1 93.3 13.9 2.8 40.3 36.2 6.8 Post-surgical feces 19.8 90.6 15.4 3. 0" 34.4 37.3 9.4 Table 2. Coefficients of digestion for pre- and post-surgical digestion trials Dry Organic Protein Ether Crude N-free matter matter (Nx6.25) extract fiber extract Ash % £5 75 z 5% z z Pre-surgical coefficients 68.2 68.6 74.3 66.7 49.7 77.9 61.3 Post-surgical coefficients 69.3 70.5 72.5 59.3 52.8 78.1 48.1 Establishment of the re-entrant duodenal fistula appeared to have no marked influence on the total digestive ability of the animal. Coefficients of digestion for dry matter, organic matter, protein and N-free extract were in relatively close agreement whereas the differences between the values for ether 208 extract, crude fiber and ash were somewhat greater. The coefficients Of digestion for those components which are known to be complicated by the excretion of endogenous materials (protein, ether extract, ash) in the feces were lower after establishment of the fistula. This suggests that the excre- tion of substances of endogenous origin was increased as a result of fistulation. On the other hand, digestibility of the carbohydrate fractions (crude fiber, N—free extract) was greater in the fistulated animal. Changes in weight, urinary excretion and water intake were essentially the same for both digestion trials. Although these data are limited, they do offer a measureable degree of confidence for assuming that the functional activities (digestion, etc.) of the animal were not disturbed to any great extent by fistulation. Establishment of method of collection Analyses of the alfalfa hay and the corn—mineral mix fed during the duodenal trials are shown in Table 3. Table 3. Chemical composition of feed for duodenal trials Dry Organic Protein Ether Crude N-free matter matter (Nx6.25) extract fiber extract Ash % % % % fl % % Alfalfa hay 86.7 91.7 20.8 9.9 23.1 44.8 8.3 Corn-mineral mix 87.6 95.9 10.5 4.7 2.1 78.7 4.1 209 Physiological effects of method of collection Table 4 summarizes some of the physiological effects of the methods of collection on the animal. The average increases in body weight obtained as a.result of feed and water intake with method I was minor when compared to the average increases Obtained with Table 4. PhysiOlOgical effects of method of collection I II III NO 15 minute Continuous return return return Wt. change (lb.) 5.5 24.5 52.0 Feed intake (1b.) 10.0 10.0 10.0 water intake (lb.) 29.6 50.4 51.2 Feces excreted (15.) 1.1 4.5 3.6 Urine voided (1b.) 6.7 6.6 4.6 Time eating (min.) 86.0 85.0 69.0 Duration eating (min.) 150.0 101.0 87.0 Time ruminating (min.) 50.0 62.0 75.0 methods II and III. This was not unexpected for no ingesta was re-introduced into the lower gut with method I. The dif- ferences in weight change observed between methods II and III could be accounted for by the differences in water intake and feces and urine excretion. Water intake was not markedly in- fluenced by the method of collection but it was somewhat 210 higher when ingesta was re-introduced. Feces excretion, as might be eXpected, was greater when ingesta was returned to the lower gut. Urinary excretion was markedly higher when methods I and II were employed despite the fact that water intakes were lower and water losses, other than as urinary losses, were higher during these collections. It is specu- lated that a decrease in the electrolyte content of the plasma may have been involved, thus leading to water diuresis. Effegt of method of collection on eating and rumination The patterns of eating and rumination (Figures 15a,b; 16a,b; l7a,b) for each method of collection are also summarized in Table 4. The time spent eating during continuous re-introduc- tion was less and was confined within a shorter span of time than when the other methods were employed. There did not appear to be any obvious changes in the general behavior of the animal which would account for the differences in eating behavior. On the other hand, when no ingesta was returned to the lower gut or when ingesta was re-introduced at the end of each sampling period the animal's behaviour was manifested by an unusual amount of treading and restlessness which appeared to influence the amount of time spent ruminating. This was particularly noticeable when no ingesta was re-introduced. In addition, behaviour during collections involving method I was further characterized by excessive licking and chewing on the bars of the collection stall and, at times, by intense shiver- ing. These reactions, which did not commence until approxi- 211 Figure 15a. Effect of no re—introduction on the flow of ingesta from the duodenum. Collection I. R, rumination. E, eating. Figure 15b. Effect of no re-introduction on the flow of ingesta from the duodenum. Collection II. R, rumination. E, eating. 212 R ___‘___JU—"" UJLHJ _JIJTJT: m L m O O 1 VOLUME (M (I) o o l 400 3 4 5 6 TIME (HR) m1) 2 3 - 21200 LlJ 2 D _ _J 800 O > 3 TIME (HR) 213 Figure 16a. Effect of lS-minute re-introduction on the flow of ingesta from the duodenum. Collection I. R, rumination. E, eating. Figure 16b. Effect of l5-minute re-introduction on the flow of ingesta from the duodenum. Collection II. R, rumination. E, eating. VOLUME(ML) VOLUME (ML) 214 EdwT-LIM_ IZOO‘ on O O 1 b O O 2 3 4 5 6 TIME (HR) E I200- 800- 400 3 TIME (HR) 215 Figure 17a. Effect of continuous re-introduction on the flow of ingesta from the duodenum. Collection I. R, rumination. E, eating. Figure 17b. Effect of continuous re—introduction on the flow of ingesta from the duodenum. Collection II. R, rumination. E, eating. 85 TIME (HR) _ O O O O Q 8 J§vm2340> IZOO‘ Is: mszjo> A 400 4 3 HME(HR) 217 mately three hours after the collections were initiated, were presumably due to the extensive loss of ingesta. Symptoms of hunger and of a considerable loss of body heat were evident. Eggect of method of collection onppattern of flow of ingesta Ingesta.passed from the proximal duodenum in gushes and trickles at irregular but relatively frequent in- tervals throughout the collection periods. Flow of ingesta, though variable in amount, occurred in every sampling period regardless of the method of collection. The patterns of flow for each method of collection are shown in Figures 15a,b, 16a,b and l7a,b. These patterns are to some extent misleading for they indicate that the passage of ingesta was relatively continuous for all methods of collection. This was not the case and was primarily the result of arbitrarily setting sampling period limits of 15 minutes. In many instances the passage of ingesta occupied only a comparatively minor por- tion of the total time within a given sampling period. From this standpoint the continuous recording of passage would offer a much more accurate method for obtaining an actual flow pattern. The patterns also tend to indicate some rhythmicity of flow but again it is difficult to draw any definite con- clusions due to the arbitrary boundaries established for the sampling periods. Flow, when no ingesta was re-introduced into the lower gut, was characterized by an almost continuous passage of in- 218 gesta from the duodenum with few intervals between gushes that exceeded 2-3 minutes. Again, in many of these instances some ingesta continuously trickled into the collection tube. This was in sharp contrast to the pattern of flow observed when ingesta was re-introduced at lS-minute intervals for with this method there were frequently periods of 10-12 minutes in which no ingesta was passed at all. The continuous return of mate- rial into the lower gut resulted in a pattern of passage some- what intermediate to that observed with the other methods. Prolonged intervals (5—8 minutes) between rushes of ingesta were experienced only when large quantities of ingesta were passed from the duodenum in a single gush. The rapid re-introduction of large amounts (approximately 200 ml. or more) of ingesta into the duodenum at one time in- variably reduced or st0pped flow for a subsequent period of time. Duration of the inhibitory effect appeared to be re- lated to the quantity of ingesta re-introduced although this was not always the case. Response to the re-introduction of comparatively smaller amounts (less than 200 ml.) of ingesta was more variable; at times flow was reduced and in other in- stances it was increased. Visual observation of flow with the U-tube in gitg indi- cated it was similar to that with the U-tube removed. It dif- fered, however, in one important aspect. A certain amount of back-flushing through the U-tube always occurred following 219 each forward rush of ingesta. This was obviously not possible with the U-tube removed as no provision had been made for out- flow from.the proximal duodenum to occur against a hydrostatip pressure such as exists intraduodenally. The influence of this factor upon flow was not determined. Effect of methodZQf collection on pH of ingesta Changes in duodenal flow resulting from the different methods of col— 1ection were reflected by changes in pH of the ingesta. The pH of ingesta passing from the duodenum for each collection (Appendix Tables la,b; 2a,b; 3a,b) is summarized for each method of collection in Figure 18a,b,c. The relationship be- tween pH and flow did not appear to be absolute, but the data do suggest that high flow volumes were acc0mpanied by a de— crease in pH. The average pH of the ingesta when there was no re-introduction was slightly higher (2.04) than that of ingesta collected by either of the other methods (15-minute, 1.86; continuous, 1.98). The pH remained relatively constant (when no ingesta or when ingesta was continuously re-introduced into the lower gut. 0n the other hand, re-introduction at 15-minute intervals eaused marked fluctuations in pH. One might speculate that such would be the case for this method of collection also resulted in the greatest fluctuations in flow. Effect of method of collection on the passagg of ingesta The volume and composition of the ingesta passed from the duodenum during successive 15~minute sampling periods are 220 Figure 18a. Effect of no re-introduction on the pH of ingesta passed from the duodenum Figure 18b. Effect of lfi-minute re-introduction on the pH of ingesta passed from the duodenum Figure 18c. Effect of continuous re-introduction on the pH of ingesta passed from the duodenum 2.. 221 T ‘ r T I '2 3 4 5 TIME (I IR.) 222 shown in Appendix Tables 1a,b, 2a,b and 3a,b. Passage values calculated from these tables are summarized for each method of collection in Tables 5, 6 and 7. Considerable variation was observed between collections using the same method and between Table 5. Effect of no re-introduction on the passage of total ingesta, dry matter, organic matter and ash from the duodenum Time Volume Dry matter Organic matter Ash (min.) (1111.) (g.) (g.) (g.) 15 593 19.8 15.5 4.4 30 1177 50.8 42.0 8.6 45 755 39.1 31.7 7.3 1 hr. 1783 124.4 110.9 3.2 15 590 35.1 30.3 4.8 30 422 23.6 20.2 3.3 45 648 27.4 22.6 4.8 2 hr. 692 38.6 32.3 6.3 15 640 33.5 27.9 5.6 30 775 36.9 29.9 6.9 45 538 22.7 18.2 4.5 3 hr 805 35.6 28.9 6.6 15 490 19.8 15.7 4.1 30 600 24.0 19.1 4.9 45 627 24.8 19.5 5.4 4 hr. 715 29.1 23.1 6.0 15 535 20.1 15.9 4.2 30 538 19.1 14.9 4.3 45 640 23.6 18.6 5.0 5 hr. 585 22.4 17.8 4.6 15 405 15.2 12.0 3.2 30 437 15.7 12.3 3.4 45 578 22. 17.7 4.6 6 hr. 607 24.4 19.3 5.0 223 Table 6. Effect of l5-minute re~introduction on the passage of total ingesta, dry matter, organic matter and ash from the duodenum Time Volume Dry matter Organic matter Ash (min.) (ml.) (g.) (g.) (go) 15 510 19.0 15.2 3.7 30 765 26.6 21.6 5.0 45 680 23.5 19.0 4.6 1 hr. 1043 40.0 32.4 7.5 15 1240 55.0 44.6 9.7 30 485 19.9 15.8 4.0 45 955 62.4 34.5 8.0 2 hr. 590 17.9 14.3 3.6 15 150 3.8 2.7 1.1 30 230 7.3 5.5 1.8 45 585 20 4 15.5 4.8 3 hr. 877 26.7 21.0 5.7 15 658 18.4 14.8 3.6 30 767 ‘ 32.7 26.2 6.4 45 775 31.5 24.9 6.5 4 hr. 465 17.7 14.2 3.5 15 935 34.7 27.2 7.5 30 850 34.1 25.5 8.7 45 308 8.2 6.0 2.2 5 hr. 1022 29.3 22.1 7.2 15 948 32.8 25.2 7.7 30 907 42.5 35.3 6.6 45 295 10.1 7.9 2.2 6 hr. 685 23.8 17.7 5.3 sampling periods within collections in the amount of ingesta passed from the duodenum. Oscillations in flow were most marked when all of the ingesta for a given sampling period was re-introduced at the end of that period and least marked 224 Table 7. Effect of continuous re-introduction 0n the passage of total ingesta, dry matter, organic matter and ash from the duodenum Time Volume Dry matter Organic matter Ash (min.) (mlo) go) (8.) (g.) 15 613 23.2 18.6 4.6 30 802 25.7 20.3 5.3 45 700 28.6 23.8 4.7 1 hr. 1050 48.8 40.2 8.7 15 938 42.7 34.5 8.2 30 377 14.5 11.6 2.8 45 618 23.3 19.0 4.2 2 hr. 890 33.6 27.0 6.6 15 857 30.0 23.8 6.2 30 473 14.7 11.5 3.1 45 477 15.9 12.7 3.2 3 hr. 765 27.9 22.2 5.6 15 680 24.1 19.5 4.8 30 588 18.9 15.3 4.0 45 677 21.7 18.2 4.6 4 hr. 720 22.9 16.7 4.8 15 503 17.0 13.5 3.2 30 567 16.3 13.2 3.6 45 775 23u0 19.2 5.1 5 hr. 793 26.6 22.0 5.1 15 622 21.1 17.9 4.0 30 723 25.1 19.4 4.8 45 622 19.4 15.9 4.2 6 hr. 740 24.2 21.4 5.1 when ingesta was re-introduced continuously or not at all. The volume of ingesta.passed from the duodenum ranged from 140-2840 ml./15 min. for method 1, 50-1520 m1./15 min. for methOd II and 170-1180 ml./15 min. for method III. The mean 225 passage was 674, 697 and 690 ml./l5 min. for methods I, II and III, respectively. Because the amplitude and frequency of the oscillations make it difficult to compare the differ- ences in passage between methods, regressions of passage on time (Snedecor, 1956) were computed to give values for each method which would depict the passage curve in its entirety. These values are presented in Table 8. Rate of passage was calculated from the accumulated data and represents the quan- tity passed per unit of time. Rate of increase or decline was computed from the raw data and is indicative of the general trend of the data and its rate of occurrence. Passage was initially high for all methods of collection and‘thereafter Table 8. Effect of method of collection on rate of passage and rate of decline of ingesta from the duodenum Rate of pasgage Rate of decline Method Method Method Method Method Method I II III I II III Volumea 646.3 686.1 675.2 -15.76 -O.66 -3.67 Dry matterb '29.4 25.2 25.6 -1.45 -0.09 -0.45 Organic matterb 24.2 19.9 19.1 -l.4O -0.12 -O.36 Aehb 5.5 5.5 4.7 -0.06 0.02 -0.06 8Expressed in ml. per 15 minutes. bExpressed in g. per 15 minutes. 226 gradually declined. The initial passage of contents when no ingesta was returned to the lower gut was noticeably higher than that observed when the other methods of collection were used though the calculated rate of passage over the entire collection was somewhat slower. The combined effect of this high initial passage and the passage of considerably less in- gesta during the terminal stages of the collection accounts for the very rapid rate of decline and the apparent slow rate of passage obtained for this method. The reverse appears to have been the case when ingesta was re-introduced at the end of each sampling period. Trends in passage for this method were much less repeatable than for the other methods and, in fact, where one collection showed a decline in passage with time, the other exhibited a general increase. As a result the average rate of passage over the entire collection was comparatively high whereas the average rate of decline was negligible. Continuous ingesta return resulted in rates of passage and decline intermediate to the extremes obtained with methods I and II. Close agreement between collections for these calculated rates was obtained with method III and the trends in passage of total ingesta for both collections were remarkably linear. In contrast to the passage of less total ingesta obtained ‘when the contents were not returned to the lower gut, the pas- sage of dry matter was substantially greater. The mean passage 227 of dry matter from the duodenum per 15 minutes was 31 g. (range, 15-124 g.) for method I, 26 g. (range, 4-54 g.) for method II and 25 g. (range, 14-49 g.) for method III. The differences in dry matter passage were due essentially to passage of the organic constituents for only minor differ- ences were found between methods with respect to the passage of ash. The mean quantity of organic matter passed from the duodenum per 15 minutes was 26 g. (range, 12-111 g.), 20 g. (range, 3-45 g.) and 20 g. (range, 12-40 g.) for methods I, II and III, respectively. The mean quantity of ash passed per 15 minutes for methods I, II and III was 5 g. (range, 3-13 g.), 5 g. (range, 1-10 g.) and 5 g. (range, 3-9 g.), respec- tively. ' The rates of passage of dry matter and organic matter were substantially more rapid with method I than with methods II and III. Decline rates for these fractions were likewise higher for method I and were reflections of their rapid initial passage. Continuous re-introduction resulted in the slowest rate of passage of solids. The rate of decline was consider- ably slower than that calculated for method I but was more rapid than that for method II. Again, as with total ingesta, trend repeatability between collections was good for methods I and III, but was poor for method II, which probably accounts for the slow rate of decline obtained by this latter method. The passage of ash was only slightly influenced by the method 228 of collection. Inorganic material passed less rapidly when ingesta was continuously re-introduced into the lower gut. Fifteen-minute return resulted in an increase in the amount of inorganic constituents passed as the collection progressed. Conversely, a decline in ash was observed when methods I and III were used. As the average total volumes of ingesta passed from the duodenum and their rates of passage were not indicativeof, any major differences between methods, the differences observed with regard to the solid constituents, both in the amounts ' passed and their rates of passage, were due to changes in the percentage composition of the ingesta. The average initial dry matter content of the ingesta for each method of collection was approximately 3.5 percent. Where no ingesta was re—intro- duced into the lower gut, this increased rapidly to a peak of 5.8 percent at one hour and thereafter tailed off butdid not reach its initial level within the six hour collection. Fifteen-minute re-introduction resulted in an initial fall in dry matter content to about 3.0 percent in 30 minutes followed by an increase to a peak of 4.2 percent at 75 minutes. Sub- sequent low levels were observed between 2 to 3 and 4 to 5 hours and subsequent peak levels occurred between 3 to 4 and 5 to 6 hours. >Again, as with passage of total ingesta and changes in pH, this method resulted in marked fluctuations in concentration of the various components. When continuous 229 re-introduction was used changes in dry matter content fol— lowed a pattern similar to that obtained with no re-introduc- tion. Peak concentrations (5.0 percent) were reached in one hour and thereafter declined to slightly sub-initial levels. The average dry matter contents of the ingesta collected by no, 15—minute and continuous return were 4.3, 3.4 and 3.5 percent, reapectively. The concentration of organic matter (no return, 3.5 percent; 15-minute return, 2.7 percent; con- tinuous return, 2.8 percent) was a reflection of the dry matter content and followed a similar pattern of change. Ash content remained relatively constant between sampling periods within a given method and was only slightly different between methods of collection (no return, 0.81 percent; lS-minute return, 0.77 percent; continuous return, 0.73 percent). EffectWQLZmethod of collection on the composition of ingesta The volume and composition of the ingesta passed from the duodenum during hourly intervals after feeding are shown in Appendix Tables 4a,b, 5a,b and 6a,b. Quantitative data for the ingesta components calculated from these tables are summarized for each method of collection in Tables 9, 10 and 11. The values for volume were derived by totaling the amount of ingesta for each four successive 15-minute sampling periods. Values for the ingesta components were calculated from analyses of the hourly composite samples. Passage pat- tern oscillations were naturally eliminated to a large extent 230 Table 9. Effect of no re-introduction on the quantity of ingesta components passed from the duodenum Dry Organic Protein Ether Crude N-free Time Volume matter matter (Nx6.25) extract fiber extract Ash (hr.) (ml.) (g.) (g.) (g.) (g.) (g.) (g.) (g.) 1 4308 247.0 212.2 51.8 12.6 43.5 104.3 34.8 2 2353 130.9 109.8 27.9 6.6 21.4 53.9 21.1 3 2758 131.9 107.2 31.2 7.6 24.6 43.9 24.7 4 2433 115.6 91.3 28.9 6.8 21.9 33.7 24.3 5 2298 89.6 69.9 22.8 5.4 16.4 25.4 19.6 6 2028 83.0 65.6 21.3 4.9 15.0 24.4 17.4 Table 10. Effect of l5—minute re-introduction on the quantity of ingesta components passed from the duodenum Dry Organic Protein Ether Crude N-free Time Volume matter matter (Nx6.25) extract fiber extract Ash (hr.) (ml.) (g.) (g.) (g-) (g-) (go) (go) (g.) 1 2998 116.1 93.8 26.2 7.1 25.3 35.1 22.2 2 3270 143.4 115.1 31.8 7.8 27.2 48.4 28.2 3 1843 65.9 50.1 16.6 4.0 10.8 18.8 15.8 4 2665 109.5 85.8 23.3 5.6 20.5 36.4 23.7 5 3115 119.4 90.2 27.7 7.0 20.9 34.9 29.2 6 2835 117.4 92.2 27.4 6.5 23.3 35.4 25.2 231 Table 11. Effect of continuous re-introduction on the quantity of ingesta components passed from the duodenum Dry Organic Protein Ether Crude N-free Time Volume matter matter (Nx6.25) extract fiber extract Ash (hr.) (ml.) (g.) (g.) (g-) (g.) (g.) (g.) (g.) 1 3165 128.8 101.8 28.7 9.2 23.7 40.2 27.0 2 2823 113.4 88.6 25.1 7.7 20.9 34.9 24.8 3 2573 92.4 71.4 20.6 6.6 17.9 26.3 21.0 4 2665 92.8 70.4 21.2 6.1 16.7 26.4 22.4 5 2638 87.7 66.2 20.3 5.6 15.8 24.6 21.3 6 2708 95.4 73.0 21.3 6.2 17.7 27.8 22.4 by computing the data on an hourly basis, however, passage trends were not appreciably influenced by this procedure. The mean volume of ingesta passed from the duodenum per hour was 2696 m1. (range, 2026-4506 m1.) for method I, 2766 m1. (range, 1843-3270 ml.) for method II and 2762 ml. (range, 2573-3165 ml.) for method III. The mean and range of ingesta components passed per hour for methods I, II and III, respec- tively, were as follows: dry matter, 133 g. (83-247 g.), 112 g. (66-145 g.), 102 g. (87-129 g.); organic matter, 109 g. (66-212 g.), 66 g. (50-115 g.), 79 g. (66-102 g.); ash, 24 g. (17-35 g.), 24 g. (16-29 g.), 25 g. (21-27 g.); protein, 51 g. (21-52 g.), 26 g. (17-52 g.), 25 g. (20-29 g.); ether extract, 232 7.5 g. (4.9-12.6 g.), 6.3 g. (4.0-7.8 g.), 6.9 g. (5.6-9.2 g.); crude fiber, 24 g. (15-44 g.), 21 g. (11-27 g.), 19 g. (16-24 g.); N-free extract, 48 g. (24-104 g.), 35 g. (19—48 8’): 50 g. (25.40 g.). The rates of passage and decline of dry matter organic matter and ash (Table 12) followed essen- tially the same trends as they did when calculated from the 15-minute data and thus will not be discussed further here. Table 12. Effect of method of collection on rate of passage and rate of decline of ingesta components from the duodenum Rate of passage Rate of decline Method Method Method Method Method Method I II III I II III Vqumea 2407.14 2690.69 2666.51 -559.71 ~15.09 -78.51 Dry matterb 110.66 107.76 94.66 -27.45 -O.63 -6.96 Organic matterb 69.01 65.74 72.64 -24.61 -1.54 -6.06 Proteinb 26.78 24.56 21.41 -4.86 0.01 -1.45 Ether b extract 6.35 6.00 6.34 -1.23 -0.11 -0.62 Crude riberb 20.21 19.69 17.51 -4.58 -0.55 -1.52 N-free b extract 55.67 55.57 27.56 -14.15 -O.61 -2.65 Ashb 21.67 24.00 22.17 -2.63 0.74 -o.92 8Expressed in ml. per hour. bExpressed in g. per hour. 233 Passage of each organic component from the upper gut within a given method followed the same general pattern with time after feeding. Output during the hour immediately pggt ggggm was markedly accelerated when ingesta was not re-intro- duced into the lower gut. Accelerated passage during this period likewise occurred with continuous re-introduction but to a more limited extent. Both methods were characterized by a decreased output of organic components during the second hour. Thereafter, the output progressively declined with method I while a relatively constant output occurred with method III. Passage of the organic components with 15-minute return was more variable and did not follow a trend as dis- tinct as those obtained by methods I or III. The output of protein from the duodenum varied widely both within and between methods of collection. It was inter- eating to note, however, that despite these differences the protein content of the ingesta dry matter varied within rela- tively narrow confines (20-27%). The range of variation within collections was equally as great as that encountered between collections and methods. The rate of passage-of protein (Table 12) was most rapid when no ingesta was re-introduced into the lower gut and least rapid when ingesta was continuously returned to the duodenum. Trends in passage for both of these methods, however, were similar. The rapid rates of decline, particularly for method 234 I, are again indicative of rapid passage during the initial stages of collection. In contrast, 15-minute return resulted in a very slight increase rather than a decline in passage of protein due to the increased quantities of protein passed dur- ing the terminal stages of collection. Ether extract passage, other than being more rapid during the first hour of collection for methods I and III, did not seem to be influenced to any appreciable extent by the method of collection. Again, as with protein percentage, the ether extract content of the ingesta varied within a relatively narrow range (5-8%). The higher average ether extract content resulting from continuous return (6.8% as compared to 5.7%:for methods I and II) of ingesta to the lower gut is of interest. The rates of passage (Table 12) were comparable despite the method of collection. 0n the other hand, the rates of decline differed between methods and were primarily a reflection of the amount of ether extract passed during the first hour. The amount of crude fiber passed initially was consider- ably higher with method I than with either of the other methods. Passage rapidly fell during the second hour and subsequently declined to a terminal level which was less than that obtained with either method II or III. With the excep- tion of the very low value obtained at three hours for method II, the passage of crude fiber for methods II and III remained relatively constant following the second hour post cenam. 235 Excluding the results for method II, the crude fiber content of the ingesta assumed a constancy (15-20%) similar to that found for the protein and ether extract fractions. Re-intro- duction of the ingesta at the end of each sampling period resulted in much wider variations in the percentage of ingesta crude fiber. The rates of passage of crude fiber (Table 12) for methods I and II were similar although the rate for method I was slightly more rapid. Both methods resulted in a faster rate of passage than was obtained with continuous re-introduction. Methods I and III resulted in more rapid rates of decline than method II, again reflecting a high initial passage; how- ever, the differences in rate of decline between methods were not as great with this fraction as were encountered with pro- tein, ether extract or N-free extract. Method of collection had a marked influence upon the passage of N-free extract. The amount of N-free extract passed from the duodenum with method I was initially quite high. Passage rapidly declined during the second hour and then gradually decreased throughout the remainder of the col- lection but did not reach levels of output similar to those obtained with methods II and III until the fourth hour. The quantity of N-free extract passed with method II remained relatively constant with the exception of a high value at two hours and a low value at three hours. Passage with method III 236 initially was elevated but by three hours after feeding it had decreased and attained a comparatively constant level. This level was in the same range as that for method I but levels for both methods I and III were considerably below that for method II. Greater variability within collections, between collec- tions within methods and between methods was found with the N-free extract content of the ingesta than was observed with the other organic fractions. The average N-free extract con- _tent for methods I, II and III was 31.6%, 30.3% and 29.2%, reapectively. The rate of passage of N-free extract (Table 12) was most rapid with method I and least rapid with method III. The exceedingly high initial passage of N-free extract which occurred with method I and to a lesser extent with method III is reflected in the rapid rates of decline. The rate of decline was particularly noticeable for method I for it was 20 and 7 times more rapid than that obtained for methods 11 and III, respectively. The effect of method of collection on the total quantity of ingesta components passed from the duodenum is summarized in Table 13. Method of collection had little effect on the passage of total ingesta, ether extract or ash. There was considerable difference between methods with regard to the quantity of dry matter but-this was due almost entirely to the organic fraction. Of the organic components N-free 237 Table 13. Summary of effect of method of collection on passage of ingesta from the duodenum I II III No lS-minute Continuous f re-introduction re-introduction re-introduction 1 Volume (ml.) 16176 16726 16572 Dry matter (g.) 797.6 671.7 610.5 Organic matter (g.) 656.0 527.2 471.4 Crude protein (g.) 165.6 155.0 157.2 Ether , extract (g.) 43.9 38.0 41.4 Crude fiber (g.) 142.9 127.6 112.7 N-free extract (g.) 265.5 208.9 160.2 Ash (g.) ' 141.9 144.5 138.9 extract was influenced to the greatest extent. The amount passed as a result of method I was 27 and 37 percent greater than with methods 11 and III, respectively. The quantities of protein and of crude fiber passed from the upper gut were likewise substantially higher with method I than with the other_two methods. The differences between methods, however, were not as great as those encountered with the N-free extract fraction. If it is assumed that the amount of a given component 238 entering the upper gut per day is equivalent to the amount of the same component leaving the upper gut per day by absorption and passage to the lower gut then an "input-output" balance can be determined directly by measuring the component leaving the upper gut with time and by eXpressing its passage as a percentage of its intake. If no addition or removal of the component has occurred the eXpected mean passage would be about 4.2 percent of intake per hour. A comparison of the output values in Table 13 with the input values in Table 3 indicates that protein, crude fiber and N-free extract were removed from the ingesta. This was particularly the case with N-free extract which had a mean rate of removal of 2.0-2.8 percent per hour. On the other hand, both ash and ether ex- tract were accumulated in substantial amounts. The addition of material to or the removal of material from a given com- ponent was independent of the method. Method of collection influenced only the extent to which the process took place. Discussion The deveIOpment of fistula techniques for studying diges- tive physiolOgy in ruminants has prOgressed rapidly in spite of repeated criticisms of the validity of results obtained by such techniques. In this study the effectscf placing a re— entrant fistula in the duodenum were estimated by comparing the coefficients of digestion obtained before surgery with 239 those obtained after surgery. Similar procedures have been employed for validating the results obtained with other types of fistulas. The pre- and post-surgical digestion coeffi- cients indicate that establishment of the re—entrant fistula had little effect upon the digestive ability of the animal although there was some suggestion that the excretion of sub- stances of endOgenous origin (protein, ether extract, ash) was increased. Other criteria such as weight change, urinary ex- cretion, water intake and general behaviour during the trials were similar. Thus, it would appear that the functional activities of the animal were not measurably disturbed by fistulation. It is difficult to say what the normal should be for some of the physiolcgical phenomena measured, however, certain dif- ferences in reaponse between methods occurred which appear worthy of mention. The water intakes were slightly lower with no and 15—minute re-introduction than with continuous re-introduction of ingesta into the lower gut but they were not great enough to be significant. Similarly, the average number of drinking periods was about the same for each method. The relative times during the collections in which the drink- ing periods were distributed were quite different. With 15- minute and continuous reéintroduction the number of periods of drinking was approximately the same in the first 2 hours after feeding as it was in the last 4 hours whereas with no 940 re—introduction most of the periods of drinking occurred after the first 2 hours. Again, considerably more of the drinking periods occurred in the last 5 hours of the collections with no and l5-minute return than occurred during this same period of time with continuous return. Although the water intake for each period of drinking is not known, the distribution of periods suggest that water was consumed for the most part dur- ing the latter part of the collections when ingesta was not re-introduoed, throughout the collections when ingesta was returned at lS—minute intervals and primarily during the initial stages of the collections when ingesta was continuous— ly returned to the lower gut. If there was a relationship between water intake and the passage of ingesta at any given time, it was not reflected by any of the parameters of the experiment. Urinary excretion, which was higher with no and l5-minute re-introduction than with continuous re-introduction, was also of considerable interest. This elevated excretion occurred in spite of the fact that water intakes were lower and water' losses, other than as urinary losses, were higher during these collections. According to Dukes (1955), a slight decrease in the electrolyte content of the plasma may suppress the produc- tion of the antidiuretic hormone and thus lead to water diuresis. Since the data are much too limited to draw any definite conclusions, it is mere supposition that this might 241 have been the mechanism involved. Differences between methods with respect to the amount of time Spent eating and the duration of eating were unexpected. There did not appear to be any visible alteration in the be- haviour of the animal which would account for these differ- ences. The eating behaviour did not seem to be unusual with any of the methods for the animal ate steadily until a large portion of the meal was consumed. Towards the end of the meal eating always became Spasmodic and was interspersed with periods of drinking or idleness. Balch (1958) has reported similar eating behaviour for cows which received a wide vari- ety of rations. The patterns of eating obtained in this study suggest that the method of collection exerted an almost imme- diate effect, for the initial period of eating was more pro- longed and the lapses of time between subsequent periods of eating were greater with no and lE-minute re—introduction than with continuous re-introduction. This was particularly true where ingesta was not returned to the lower gut. According to available evidence, it is difficult to alter the pattern and amount of time spent ruminating other than by an alteration of the physical makeup of the ration (Dukes, 1955; Gordon, 1958a, 1958b, 1958c). Estimates of the daily rumination times in cattle range from 5.9 to 8.9 hours (Gordon, 1958a). If the amount of time spent ruminating is calculated on a 24—hour basis for the collections in which continuous 949 re-introduction was employed, it is seen that about 5 hours would have been Spent in rumination. Neither the time at which rumination was initiated after feeding nor the average number of periods spent ruminating were markedly changed by the method of collection. On the other hand, the average amount of time spent ruminating in a given period was shorten- ed and consequently, the total rumination time was reduced with no and lS-minute return. It is speculated that the irregular behaviour of the animal, which commenced about 5 hours after these collections were initiated, was responsible for the reduction in rumination time. The fact that the most irregular behaviour resulted in the greatest reduction in rumination time lends support to this premise. That the stomach of the dog empties at a rate which is far slower than it is physically and physiologically capable of achieving has been known for a long time. This is substan- tiated by the fact that if ingesta leaving the stomach of the dog are allowed to flow from the proximal duodenum through an open fistula the stomach empties more rapidly than normally. Re-introduction of the ingesta so obtained into the intestine beyond the fistula produces a normal emptying time of the stomach (Alvarez, 1940). Phillipson (1959) showed that the same principle was true for the sheep. The eXperiments_re- corded here indicate that this principle is also applicable to the bovine. Flow from an Open fistula was almost continu- 245 ous. This was in sharp contrast to the intermittant flow ob- tained when ingesta was re—introduced into the gut, and par- ticularly when it was re-introduced at l5-minute intervals. Nevertheless re-introduction of the ingesta resulted in a higher mean flow (continuous, 690 ml./l5 min.; l5-minute, 697 ml./15 min.) over a 6-hour period than when the ingesta was not re-introduced (674 ml./15 min.). If only the first hour and one half of each collection are considered however, then the results agree with those obtained by Phillipson (195°) for the sheep. The mean flow with no re-introduction during this period was 887 ml./15 min. whereas it was 787 and 747 ml./ 15 min. with lS-minute and continuous re-introduction, reSpec— tively. Thus, it would seem that the initial rapid outflow was at least in part an emptying of the abomasum in reaponse to the Open duodenal fistula and that the subsequent, less rapid outflow was dependent upon the inflow of ingesta from the reticulo-rumen and omasum. Mechanical distention of the duodenum or small intestine of the dOg inhibits gastric emptying (Alvarez, 1940; Thomas, 1957). Phillipson (1959) found this was also true with sheep, for the presence of a small balloon in the duodenum reduced the outflow of ingesta from the abomasum. The rapid re-intro- duction of large amounts of ingesta into the lower duodenum Tfiflears to exert a similar effect. Flow was usually reduced oI'cOmpletely inhibited for a period of time. Duration of the 944 inhibitory effect appeared to be related to the quantity of ingesta re-introduced although this was not always the case. This was particularly evident when ingesta was re-introduced at lS-minute intervals. The short periods of time in which outflow was reduced or completely abolished did not seem to markedly influence the total quantity of ingesta passed over a 6-hour period. The initial passage of ingesta was rapid for each method of collection. Balch (1958) found that outflow from the reticulo-rumen was accelerated during eating. This in turn would tend to increase the volume of ingesta in the abomasum and, according to Thomas (1957), gastric emptying is a function of the volume of gastric contents. Wasteneys gt gl. (1941) observed that normal emptying of the stomach of the dog takes place when provisions were made for outflow to occur against the hydrostatic pressure which exists in the intestine. Under conditions where flow was not against a hydrostatic pressure, alterations in consistency of the ingesta were noted and the rate of gastric emptying was increased. Flow of ingesta.with each method of collection was subject to the effects of eating and the rapid initial flow was probably due in part to this factor. To what extent hydrostatic pressure participated in the rapid initial passage or passage at any other time is dif— ficult to say for although a hydrostatic pressure was maintain- ed in the segment of duodenum into which the ingesta was 1 Q l C I ‘ ‘ 'l\ a» O 0"“ no +L 2 r a: n.“ «Va 6 o . .1. O 1 i :C H» Rd 1 . . . a... o 3. o u C. Cy O Fab - J Q- U _ III Pv. on.» .1. :- . .. .su. I O ‘ Qafl ..s fr: ‘0' me 011 Has ..,, 9‘: In. .i-iP ~-.. ('0 \4 'u yer. 245 re—introduced, there was none in the short segment of duodenum immediately posterior to the pylorus and anterior to exterior- ization of the flow. It is presumed that all methods were equally influenced by this factor and that any differences in passage, as well as other physiological reSponses, were pri- marily reflections of the method of re-introduction (or no re- introduction). The rate of passage of total ingesta over a 6-hour period ranged from a low of 646 ml./l5 min. when ingesta was not re- introduced into the lower gut through an intermediate value of 675 ml./15 min. when ingesta was returned at the same rate as collected to a high of 686 ml./15 min. when ingesta was re- introduced at l5-minute intervals. This amounts to a maximum difference between methods of only 960 ml. in 6 hours and can not be regarded as significant in view of the variations be- tween collections within methods. On the other hand, differ- ences in the time-flow relationships between methods were sig- nificant. The rate of ingesta decline with no return (—16 ml./ 15 min.) was four times more rapid than it was for continuous re-introduction (-4 ml./15 min.) and P4 times more rapid than it was with 15-minute return (-O.7 ml./l5 min.). Passage of dry matter from the upper gut was markedly in- fluenced by the method of collection. Wasteneys gt al. (1941) found in dOgs that the consistency of ingesta discharged from an open fistula was at first quite fluid but it became pro- l. - “33C 2 “at I s «L .l ‘3' \ ‘v.:sca a V ~§ fl ‘ v ‘\ H 4‘ /7 ~ p.‘ H I 4. 'H us “ a. :S ‘ Qh~fi "“2“: .“ Sm ‘ fl: ‘Q‘;n£ ' ~ 01') + L Q Q‘P‘mnh “'v... x u) .w ?46 gressively less fluid with time until it finally flowed with difficulty. If provisions were made for the flow of ingesta to occur under the hydrostatic pressure (about 5 inches of water) which exists in the intestine, the consistency of the ingesta appeared to remain unchanged throughout the eXperi- ment. A similar effect was noted in this study for, when in— gesta was not returned to the lover gut, the concentration of dry matter in the ingesta increased and remained higher (mean, 4.5%) than when ingesta was re-introduced (mean, 3.4-3.5%). If the ingesta entering the abomasum was of the same dry mat- ter concentration regardless of the method of collection then it might be logically concluded that the differences between methods in the concentration of ingesta leaving the abomasum were merely an effect of the extent of dilution by gastric Juice. It appears that this was not the only factor involved, however, for there was also quantitatively more dry matter passed from the upper gut with no re-introduction (mean, 31 g./l5 min.; rate, as g./l5 min.) of ingesta then with re- introduction (mean, O5-?6 g./15 min.; rate, 04-”5 g./15 min.). This suggests the existence of an intestinal or abomasal mechanism which either directly or indirectly has a regulatory effect on the passage of ingesta from the omasum and/or reticu— lo-rumen. Phillipson (1959) observed that distention of the abomasum inhibited the force and frequency of reticulum contractions a ‘1 ‘, fin“ 1"“ 5.3;. quL' vow-291 m I‘Js‘w ... r 1‘ in «necer fturxi 2:1 bizior. o: CSE'SVQI" 35.1",07 ‘ ‘o . h N 1301‘s: 1! “it“: ‘ v 'Q J buvp‘ L .17 ‘4 1 $\ ‘V‘ H. .. 8::ihs a). F rf‘fl u. .‘ 1‘3’; L ~e t‘r kl ‘L "-p fit; U . Lust. 947 and that partial or complete evacuation of the abomasum caused normal motility to resume. These observations were confirmed in decerebrate sheep and goats by Titchen (1958), who also found that manipulation of the pylorus caused profound inhi- bition of reticulum contractions. He was of the opinion, however, that this mechanism was similar in nature to disten- tion of the abomasum. Emptying of the abomasum in decerebrate preparations caused the reticulum contractions to occur at a markedly increased frequency. A reduction in the pH of the abomasum to between 0.9 and 1.0 also stimulated reticulum contractions but it should be pointed out that this pH is lower than that of the abomasal ingesta of the conscious, fed animal. Intrareticulo-rumenal factors which have been found to increase the frequency of reticulum contractions are stretching of the reticulum walls (Titchen, 1958) and increas— ing the consistency of the ingesta (Phillipson, 1959: Balch, 1958). Balch at al. (1951) have shown that movements of the reticulo-omasal orifice and the omasum bear a constant and characteristic relationship to motility changes of the reticu- lum. It is known that the frequency of the cycles of contrac- tion of the reticulum and omasum are greatly increased during eating and it appears reasonable to assume that this would also be the case if the abomasum were rapidly emptied. On the other hand, rumination is known to reduce this frequency a: distant “ESE-3.158. ‘l"‘*y ‘_ .v‘ is“? “he 248 and distention of the abomasum would seem to evoke a similar reaponse. Available evidence indicates that the transfer of ingesta through the reticulo-omasal orifice occurs at a defi— nite stage in each cycle of contraction. Thus, factors which alter the frequency, as well as the extent to which the ori- fice Opens and closes, will likely be of considerable impor- tance in ingesta transfer. Stevens gt al, (1960) obtained evidence which suggests that the omasum acts as a two-stage pump, aSpirating reticular contents into the omasal canal, pumping the more fluid ingesta from the canal into the omasal body and finally eXpressing the omasal body contents into the abomasum. The rate at which the canal pumped ingesta seemed to be related to the rate of contraction of the reticulo-rumen. The amplitude of the omasal canal contractions appeared to be controlled at least in part by the degree of abomasal filling: mmflwing of the abomasum enhanced and distention inhibited the amplitude of omasal canal contractions. Contraction of the Omasal body occurred irregularly and appeared to be trig- gored by distention of the omasal body. The evidence from these studies, as well as that from the present study, indicate that a coordinated intestinal-abomasal-reticulo-0masal mechan- ism is involved in ingesta transfer, that the transfer of in- gesta fPOm the reticulo-rumen is subject, for the most part, to quantitative rather than qualitative regulation and that alteration of the ingesta in the abomasum is due to the extent ’“ (no “HQ- 44* , 15158 r: 213,? “2‘ : ‘“;lelg Zia Tstno ‘2. 3'; I"! P7352; ?49 of dilution by gastric Juice. Progressively less dry matter was passed down the tract from the upper gut with time after feeding. Similar declines in dry matter passage have been observed in sheep with duodenal fistulas (Masson and Phillipson, 1959; Hogan and Phillipson, 1960) and in cows and steers with rumen fistulas (Balch, 1958). In this study the rapidity with which the dry matter was initially passed is projected by the rates of dry matter de- cline (no, -l.5 g./l5 min.; lS—minute, -O.1 g./15 min.; con— tinuous, -O.4 g./l5 min.). The initial decline appeared to be associated with eating and with the method of re-introduc- ing ingesta into the lower gut whereas the decline during the latter part of the collections suggested a progressive reduction in the amount of dry matter passed from the reticulo— rumen. Balch (1958) found, in fact, that this was the case. In cows fed once-a-day the amount of dry matter in the reticulo- rumen progressively and linearly declined after eating. The rate of dry matter loss during eating was 9—3 times as great as the rate of loss between meals. As a result, the passage of dry matter over the entire cycle was curvilinear. Passage of organic matter from the upper gut essentially paralleled that of dry matter and was similarly influenced by the methods of collection. When ingesta was not returned to the lower gut, the concentration of organic matter increased and remained higher (mean, 5.5%) than when ingesta was H O .51: ..‘". v ( or’flf‘g" .oc'to J“ 'n'hi ‘0: ‘Ls -w. !i 'i _-A‘ . ~ .2 .31" 02‘ V n «ci .1?! a:— .V s ', as ‘1‘- . ~o.‘ 950 re-introduced (mean, ?.7-?.8%). There was also quantitatively more organic matter passed from the upper gut with no re- introduction (mean, as g./15 min.; rate, 04 g./15 min.) of ingesta than with re-introduction (mean, PO g./l5 min.; rate, 19-90 g./l5 min.). PrOgressively less organic matter was passed down the tract with time after feeding. The rapidity with which the organic matter decreased is illustrated by the rates of decline (no, -l.4 g./l5 min.; lS-minute, -O.l g./ 15 min.; continuous, -o.3 g./l5 min.). The rate of decline for organic matter with l5-minute return was relatively more rapid than it was for dry matter. With this method the in— organic fraction showed a correSponding increase rather than a decline with time. Passage of the inorganic constituents was of consider- able interest for it was least influenced by the method of collection. The concentration of ash was exceedingly constant for a given method and differed only slightly between methods (no, 0.81%; l5-minute, 0.77%; continuous, 0.73%). The mean quantity (5 g./15 min.) and rate of passage (5 g./l5 min.) of ash were about the same irreSpective of the method. The rela- tive constancy of ash passage for each method is illustrated by its almost zero rate of increase or decline. Changes in duodenal flow as a result of the different methods of collection were accompanied by changes in the pH of the ingesta. Hill (1955) found that gastric secretion in . w r? minant n 5‘! ,7. H . "H‘wn fvu_ 'Su’? ‘1 251 ruminants was not continuous in the absence of secretory stimuli. Secretion was due to specific stimuli, the most im- portant of which was the passage of ingesta from the reticulo- rumen to the abomasum. Since ingesta moves more or less con- tinuously from the reticulo-rumen through the omasum to the abomasum (Balch at a;., 1951) it follows that gastric secre- tion is probably more or less continuous. According to Masson and Phillipson (1959) approximately two parts of.gastric Juice are added to each part of ingesta entering the abomasum. Ingesta passes from the abomasum into the duodenum throughout the day at a fairly steady rate and with only minor changes in composition (Phillipson, 1959; Masson and Phillip- son, 195a; Hogan, 1957; Hogan and Phillipson, 1960). Ash (1959a, 1959b) found that the acidity of the abomasal contents flowing into the duodenum fluctuated only within narrow limits in individual sheep under extremes of fasting and feeding. These studies infer that inflow, abomasal secretion and out— flow are coordinated. The pH data obtained in this study appear essentially to support this contention. The pH values for a given method of collection remained relatively constant, with the widest fluctuations in pH accompanying the widest fluctuations in flow (ls-minute re-introduction). The most rapid outflow of ingesta from the abomasum was accompanied by the most acid pH while the least rapid outflow was accompanied by the least acid pH. Ash (1959a) suggests that acid controlli 355 ~~§L‘ r m, s .- .f in “.8: ?5? that acidity of the abomasal ingesta may be one of the factors controlling outflow. According to Thomas (1957), however, the regulatory function of gastric acidity at the usual concentra- tions is probably not very important, at least in simple— stomach animals. Whether there is a difference in this regard between ruminants and non-ruminants is not known. If the present data are considered in light of the passage of solids rather than total ingesta, it would seem Justifiable to con- clude that solids were passed through the abomasum more rapid- ly when ingesta was not re-introduced into the lower gut and consequently were diluted to a lesser extent by gastric Juice. As a result there was less total outflow and the pH of the ingesta was less acid. Conversely, when ingesta was re~ introduced, the passage of solids was less rapid, the solids were diluted to a greater extent, there was greater total outflow and the pH of the ingesta was more acid. Thus, it would seem reasonable to assume that acidity of the abomasal contents was only coincidental with dilution of the solids entering the abomasum and played no part in gastric emptying DEE §§~ Passage from the upper gut was estimated on the basis of hourly data in addition to its estimation on the basis of lS-minute data for two reasons: 1) composite samples of in- gesta from at least a one-hour sampling period were required to insure sufficient ingesta for detailed analysis and 9) it '1 ‘ ' AMI“ 4.1.; C! i.::erval ‘ )5 1 «11 l I $1) < 1- r1 :'=’ fliz co-‘ - ‘§ m: “u n: 3" 5889:: fit h.v o,‘ e bQ \ a £57“ 955 seemed desirable from the standpoint of future studies to determine whether the passage data obtained by this procedure would be different from the passage data obtained at 15—minute intervals. If graphic portrayals of the values for volume, dry matter, organic matter and ash are compared, it is seen that fluctuations in the passage patterns were largely elim- inated in the hourly data but the general trends in passage were not appreciably altered. Thus, aside from a considera— tion of sample size, it appears the hourly data are equally as valuable as the l5-minute data for estimating the rates and trends of passage. Again, if detailed analyses are to be per- formed, sample size is a primary consideration. On the other hand, l5-minute data would seem more desirable if precise time-passage relationships were desired. Even in this regard the data are somewhat difficult to interpret due to the irregu- larity of flow within a given sampling period. The accuracy, as well as the validity of the data, would be increased con- siderably by a simultaneous and continuous recording of the phenomena being evaluated. The salient differences between methods with respect to the passage of total ingesta, dry matter, organic matter and ash have been discussed previously with respect to the 15— minute data and consequently will not be discussed further at this point. .Because the primary difference between methods occurred in the passage of organic matter, method effects on tic-3 ind iv ..' V . -. (tie 8:3 ; c .1393: w: ‘:':::u: a .A ‘ ”firm 9.? ' ‘ t“ 9!": .\ 'Is b “ s1 EH! Lt: q..h‘ .‘vvu'c I h . "A‘ ( 1"... 0 v - ‘~ - ‘10. *UI ‘- \ ‘4‘. \. ~‘i: “n‘ ‘I ~ .1, . 4 0: x at “.“Erh‘ ‘ ‘10. “ \ fie . ‘V 'r N»! s ..‘ 'iz‘ 954 the individual organic components were of considerable inter— est. The data indicate that the concentration of organic components in the ingesta leaving the abomasum was influenced very little by the method of collection, and that the differ— ences which did exist were due, for the most part, to dilution in the abomasum. There seemed to be Specific differences, though, that could not be attributed entirely to this factor. Examples of this were the relatively higher concentration of ether extract with continuous re—introduction and the greater differences, relative to the other fractions, between methods for the concentration of N-free extract. There does not appear to be any ready eXplanation to account for the behaviour of the ether extract fraction. The concentration of N-free extract was highest with no return (51.6%), intermediate with lS-minute return (50.5%) and lowest with continuous return (a9.2%) of ingesta to the lower gut. Smith _e_g g1. (1956b) ob- served that hay and grain particles follow distinctly differ- ‘ent pathways in passing through the rumen. Paloheimo and Makela (1959) found that the constituents of grain pass from the reticulo-rumen much faster than the constituents of hay. Both Phillipson (1959) and Balch (1958) reported that the con- sistency of ingesta in close proximity of the reticulo-omasal orifice was increased appreciably, particularly immediately post cenam, when grain was fed singly or in combination with hay but not when hay alone was fed. It appears reasonable to fzr rapid se tration of N we: to a g 955 assume that this was also the case in the present experiment for rapid sedimentation of the corn would influence the concen- tration of N-free extract in the bottom strata of the reticulo- rumen to a greater extent than the other organic constituents. Visual observation of the amount of corn which settled out in the‘samples taken for analysis tended to support this conten- tion. The concentration of protein in the ingesta reacted to method effect in much the same fashion as N-free extract but to a lesser extent. According to Gray (1950) the nitrOgen components of the ingesta tend to travel primarily with the solid rather than the liquid fraction, which may account for this finding. The mean output per hour of protein, ether extract, crude fiber and N-free extract with no re-introduction was 16, 14, 1? and 27 percent greater, respectively, than the output with lS—minute return. The mean output for for these same reapec- tive components with l5-minute return was 1?, 9 (less), 10 and 14 percent greater than the output with continuous re-intro— duction. On this basis the relative differences between methods indicate that each component reaponded similarly to a given method of collection with the exception of N—free extract which was passed in substantially greater amounts as a result of no re-introduction. Method of collection appeared to have little influence on the rate of passage of ether extract and only a slight effect ‘Q 0."; £18 I"? ‘ ‘ nfif‘ D V] l ' ' t : Hod'h- 5 295:9. C 12,? 1mm: hustg g - in a .5“ ‘*5 P99: 9,!" f‘DSQNQ “iv 0 :‘fi': 1 ‘t'uiC c , I “?3Tidr A «‘5. D i.‘ D ::‘,.l ‘s H . _ (19 ?56 on the rate of passage of crude fiber. On the other hand, protein and N-free extract were passed considerably more rapidly as a result of no return or return at l5-minute inter- vals than as a result of the continuous re-introduction of in- gesta. Output of the various organic components during the hour immediately pp§t_gggam was markedly accelerated when ingesta was not returned to the lower gut. Again the effect of this method on the N-free extract fraction was noteworthy. Accelerated passage during this initial period also occurred with continuous and lS-minute return but to a more limited extent, respectively. In general, the effects a given method had on the mechan- isms regulating the passage of solids, and more Specifically passage of the organic fraction, were exerted on the individual organic components as well. Reaponse of the N-free extract fraction to the non-return of ingesta to the lower gut sug- gests an additional mechanism whereby the passage of corn from the upper gut was accelerated. Smith _3 al- (1956b) observed that, although the grain particles of a mixed diet were ini- tially distributed throughout the rumen ingesta after eating, they rapidly settled to the floor of the reticulo-rumen and then passed on to the omasum. This has been substantiated by Balch (1958) who found that the consistency of ingesta in close proximity of the reticulo-omasal orifice was increased appreciably, particularly right after feeding, when grain was .fid av AVI- ah» A44 1 f‘ -;L ~E"~< V.g.“C!‘ § n ‘3 t O 2. S .~-L .. c‘ .l‘. .‘dL. 957 fed singly or in combination with hay but not when hay alone was fed. According to Balch gt gl. (1951) and Stevem3§t_gl. (1960) transfer of ingesta through the reticulo-omasal orifice occurs at a definite stage in each cycle of contraction. As a result, factors which alter the frequency, as well as the extent to which the orifice Opens and closes, will probably alter the transfer of ingesta. Thus, even under normal con- ditions, there is a tendency for grain to pass more rapidly from the upper gut than hay, and there is, in fact, ample evi— dence in support of this point (Schalk and Amadon, 1998; Balch, 1950; Balch, 1958; Paloheimo and Makela, 1959). If normal passage is influenced further by the effects of abomaso-intestinal emptying, it seems reasonable to assume that passage of the N-free extract fraction would be markedly accelerated as it was in the present eXperiment when ingesta was not returned to the lower gut. If valid estimates of quantitative digestion in the upper gut are to be obtained using a re—entrant duodenal fistula technique, the method of collection should satisfy, as nearly as possible, the following criteria: 1) the behaviour and functional activities of the animal should remain physiolOgic- ally normal throughout each given collection period (94 hours) and 2) on a constant ration and intake, the output of ingesta components should be reasonably repeatable from collection to collection. Within and between collection variations should :e tiniral. . '. ‘1 V isms-me. o. .‘ ‘ 2:: mrepeai Pl .l-hsc v‘-» eof1 « 1!!) “3.1, “tn ‘V .ui.‘:duc1 D!- a A ‘ . “h ‘1‘ Fr‘ [4 q " g ‘—‘ 3‘ ,‘ ".‘a‘h~ . w? :e J. H \w. s ’0 ‘ J‘v 3‘)ch t I‘, UDQ * .vrabi I ;. :1 W 1°19 :‘29 .h‘. "1“ «4e 3:» ... P:‘{ :'.‘a\ ?58 be minimal. Obviously no re-introduction and lS-minute re- introduction failed these criteria on several counts, the most important of which were the anomalous behaviour of the animal, the irrepeatability between collections and the accelerated passage of the organic fraction. On the other hand, continuous re-introduction appeared to satisfy the criteria reasonably well. The difference between collections for the organic fraction with this method was about 5 percent plus or minus 3 percent for the individual organic components. Passage trends for both collections were quite similar. Behaviour of the animal during the collections was not noticeably affected. Whether-the output of ingesta and its corresponding fractions from the upper gut with this method is typical of the output in an intact animal is not known, for there is no basis for comparison. However, from the limited evidence obtained in this preliminary experiment, it seems Justifiable to conclude that continuous re-introduction of ingesta is Dhy81010910811y more sound than either of the other methods. Summary Operative technique for establishment of a re-entrant duodenal fistula in the bovine has been described and illus- trated. The animal was fed a 70% alfalfa hay ~ 50% ground corn ration at constant intake (10 lb./day) once daily throughout the experiment. The effect of fistulation was 98! Ch Cu 9 v \— "9- K . ..‘- in; to lower aqical V I . tion D ‘ l -. S (as \ .5085 F mi, r“ H u ‘s ..‘U 3 s \. e ‘\ uEZEVio K . 959 assessed by means of pre- and post-surgical digestion trials. Special equipment was designed for the collection of ingesta from the proximal duodenum and its subsequent return to the lower gut. To establish a satisfactory procedure for obtain- ing total ingesta two 6-hour collections were made with each of the following three methods: MI - no re-introduction, MII — lS-minute re-introduction and MIII — continuous re- introduction. The effect method of collection had on physio- IOgical activity, total ingesta output, pH of ingesta, compo— sition of ingesta and rate and trend of passage with time after feeding was determined. Establishment of the fistula appeared to have no marked influence on the total digestive ability of the animal al- though there was some suggestion that the excretion of sub— stances of endOgenous origin was increased. The time Spent eating with MIII was less and was confined within a shorter span of time than with MI and M11. Anomalous behaviour after 5 hours with MI and MII resulted in a reduction of the time Spent ruminating. Rumination time was normal with XIII. Ingesta passed from the proximal duodenum in gushes and trickles at irregular but relatively frequent intervals through- out the collections. Flow was essentially continuous with NI, spasmodic with MII and intermittent with MIII. The rapid re- introduction of large amounts of ingesta into the lower gut teroraril: Eire- u't‘. v r r U, .h‘ .I‘- £21 I \«v 1'79. .‘A n: a ;' Ya“. “ - n-an U“. y. .‘i 3 :‘ ‘qisfl it“; ‘{~ .‘ c ?60 temporarily reduced or stOpped flow for a subsequent period of time. The mean quantity of ingesta passed from the upper gut per 15 minutes was 674 ml. with M1, 697 ml. with MII and 690 ml. with MIII. Considering all methods, the output of ingesta varied from 50-9840 ml./l5 minutes. Variations in flow were greatest with MII. During the initial hour and one—half the flow of ingesta was 52% (MI), 15% (MH) and 10% (MIII) greater than it was during the remainder of each collection, respec— tively. The rate of passage of ingesta was 646 ml./15 min. with MI, 686 ml./l5 min. with MII and 675 m1./l5 min. with MIII. Passage of ingesta progressively declined with time after feeding at the rate of ~16 ml./15 min. with NI, —O.7 ml./l5 min. with MII and —4 ml./15 min. with MIII. Differences in dry matter passage were due essentially to passage of the organic constituents for little difference was found between methods for the passage of ash. The mean passage of organic matter per 15 minutes was ?6 g. (rate, 94 g.) with MI, 90 g. (rate, .90 g.) with MII and 0o g. (rate, 19 g.) with MIII. Passage of organic matter declined with time after feeding at the rate of -l.4 g./15 min. with MI, -O.l g./l5 min. with.NEI and -O.3 g./15 min. with MIII. The mean quantity and rate of passage of ash with each method was about 5 g. per 15 minutes and remained relatively constant with time after feeding. The ex lf‘ .3;- with ccncentrati tions were l‘rl 961 The average dry matter concentration of the ingesta was 4.5% with MI, 5.4%~with MII and 5.5% with MIII. Organic matter concentrations were 3.5%, 9.7% and 9.8%, and ash concentra~ tions were 0.81%, 0.77% and 0.75%, respectively. In general, the passage of large volumes of ingesta was associated with a decrease in pH. The average pH of the in- gesta was 2.04 with MI, 1.86 with MII and 1.98 with MIII. pH was relatively more constant with MI and MIII than it was with MII. The concentration of solids, rate of passage of solids and pH of the ingesta appeared to be inversely related to the extent of dilution of ingesta leaving the reticulo-rumen and omasum by gastric Juice in the abomasum. The mean output and rate of passage of the organic com- ponents from the duodenum per hour for MI, MII and MIII, re- spectively, were as follows: protein, 31 g. (rate, 97 g.), 26 g. (rate, 25 g.), 03 g. (rate, 91 g.); ether extract, 7-3 g. (rate, 6.5 g.), 6.5 g. (rate, 6.0 g.), 6.9 g. (rate, 6.5 g.); crude fiber, 94 g. (rate, 00 g.), ?l g. (rate, 90 g.), 19 g. (rate, 18 g.); N-free extract, 48 g. (rate, 56 g.), 55 g. (rate, 54 g.), so g- (rate, 97 g.). Output of the organic components prOgressively declined with time after feeding, with the rates of decline being most rapid with MI and least rapid with M11. The average concentration of fractions other than N-free :jract we There h“ “ act .“-¢$' V 31‘ 2‘80: f‘p 26? extract were only slightly influenced by method of collection. The N-free extract content of the ingesta was 51.6%'Wlth MI, 30.3% with 1.111 and 99.07; with MIII. Differences in mean output, rate of passage, rate of decline and average concentration between methods were most notable for the N-free extract fraction. Protein reacted to method effect in much the same fashion but to a lesser extent. There is evidence to indicate that passage is accelerated during eating, that protein travels primarily with the N-free extract fraction and that the passage of corn from the upper gut is accelerated under certain conditions. Due to minimum variation within collections, maximum repeatability between collections and behaviour of the animal during collections the continuous re~introduction of ingesta into the lower gut is physiOIOgically more suitable for use in estimating digestibility in the upper gut than either of the other methods. he were (1) lee-tions 21281;; p5 3583 in "T. za‘ieup of Passe. ‘0 . ”A“ F: a» m0 1. u ‘- 265 EXPERIMENT I Experimental Procedure The major objectives of this part of the investigation were (1) to determine the feasability of making duodenal col— lections over a prolonged (24-hour) period, (2) to quantita— tively partition digestion in the upper alimentary tract from that in the lower gut and (5) to study the effect of physical makeup of the ration and various physiological phenomena on the passage of ingesta through the alimentary tract. The experimental animal The Holstein steer used in the preliminary investigation was likewise used for this study. The animal was in excellent condition and on the initial day of the experiment weighed approximately 750 pounds. Flow of ingesta through the U-tube, for the most part, was normal although occasional blockages of the U-tube continued to occur. Blockage was most noticeable immediately following ration changes. Since the U-tube was not allowed to remain blocked for any prolonged period of time, this was not a serious problem. Rations and feeding procedure Four different rations consisting of varying ratios of first-cutting alfalfa hay to finely ground corn were studied. +1 .28 PE. M 1.31.? ‘r. 81 a “I rrq ' Lu 526, an r . an- A ’1‘: ”P“ 'iotv .C‘U‘ ‘-‘-‘ '17‘” “ 41.1. s t. Q. “ "“vi- U H. | " ‘c. ‘Q -\ . in); J‘r ‘3 . ‘ C "., Q "5 n . ‘ . Q ‘;I\\ 3‘ A, «4“ 264 The rations and their sequence of feeding during the experi- ment were as follows: R51 and R52, 50m corn - 70% hay; R41 and R42, 100% hay; R21 and R22, 70% corn - 50% hay; R11, 100% corn. The first number in the ration designations refers to the ration; the second number refers to the number of times fed per day. In addition, the animal received chromic oxide and a mineral mix. The steer was fed a total of 10 pounds of hay and/or corn per day. The entire amount was fed at the 0-hour feeding if fed only once a day or, if fed twice daily, each component was divided equally with half being fed in the morning and the other half in the afternoon. Nine a.m. was designated as O-hour feeding time. When fed twice daily, the second portion of the ration was given at two p.m. Forty—one grams of the mineral mix were fed at the 0—hour feeding each day. Ten grams of chromic oxide were administered daily by No. 10 gelatin capsule at the 0-hour feeding. Water was available in a drinking cup and was metered on those days when the animal was in the metabolism stall. Collection and sampling‘procedures The experiment was divided into seven trials, each of which consisted of a seven day preliminary period followed by a five day fecal collection period and a one day duodenal col- lection period. A minimum of 14 days was allowed for a change— we: period 5.11.51 if t or string E 95.31 day. { 3953*. .,y ‘31; z 2 I:E no: Hf“ W» Lye I he *5 ‘. “Aer 265 over period between rations. Collections were not made on the animal if the U-tube became blocked within two days preceding or during the collection periods. Samples of hay and corn were taken daily during the fecal and duodenal collection periods and composited at the termination of the experiment. Fecal samples were obtained per rectum at 6 a.m. and 4 p.m. each day. The daily samples were composited and sub-sampled at the end of each trial. All daily samples were kept refrig- erated; final samples were frozen and stored at -200C. until they were processed for chemical analysis. The continuous method was used for collecting ingesta from the proximal duodenum and re-introducing it into the lower gut. The animal was placed in the collection stall one hour preceding the initiation of each collection to allow the animal to become accustomed to the equipment. All collections commenced with O-hour feeding and were of 24 hours duration. Fifteen minutes before O-hour the U-tube was removed and con— nection of the cannulas to the collection and re-introduction apparatus was established. The amount of ingesta collected during this preliminary period was recorded but the ingesta was not included in the first hourly composite sample. Sampling periods were arbitrarily established at 15 minute intervals and small samples were taken for each 15 minute period. The remaining ingesta for each four successive periods was then composited to form an hourly sample from which a see lizer All ingest: 3i Kart. 31; If. act 32" feces a: 55.15165 We: “"9 Proces Data 1 572,. ‘ ..‘“.Ee lr‘ w I. “we Sally 266 one liter sub-sample was obtained. All samples were imme- diately frozen and stored at ~2000. until they were processed for chemical analysis. The ingesta which was not taken as sample was maintained at body temperature for re-introduction into the lower gut. All ingesta taken as sample was replaced with an equal volume of warm Ringer's solution acidified to pH 2.0. In addition to the samples of duodenal ingesta, samples of feces and urine were taken for each collection. These samples were likewise frozen and stored at -2000. until they were processed for chemical analysis. Data recorded during each collection consisted of the change in weight of the animal, the volume and pH of the in- gesta, the time and duration of eating, the time spent rumin- ating and the periods in which rumination occurred, water in- take, the weight of feces excreted and the volume of urine voided. Ingesta volume and pH data were obtained for each 15 minute sampling period. All other data was recorded for the respective period of occurrence or for the entire 24-hour col- lection. Chemical analyses Preceding analysis the frozen samples were allowed to thaw at room temperature. Analyses for moisture, dry matter, organic matter and ash were made on the freshly thawed mate— ’29 .Y F , :b _. :sei to ‘1‘ a. n6 «: are V 15 .10 in“: “(33‘ '4 267 rial. The hourly ingesta samples and the feces samples then were dried in pyrex pie plates in a forced hot-air oven at 60°C. The dried samples were ground in a Wiley mill to pass a 20—mesh sieve and stored in brown glass bottles until analyzed. Standard A.O.A.C. methods of analysis (1957) were used to determine moisture, dry matter, organic matter and ash for the feed, feces, ld-minute and hourly ingesta samples. In addition, analyses for protein, crude fiber, ether extract and nitrOgen-free extract were made on the feed, hourly in- gesta samples and feces. Chromic oxide in the feces was deter- mined by the method of Gehrke and Baker (1954). The pH of the duodenal ingesta was determined at the time of collection by means of a Beckman pH meter. No analyses were performed on the urine samples. Results The eXperimental animal Somewhat less difficulty was encountered in maintenance of the animal during this phase of the experiment than had been encountered previously. Blockage of the U-tube continued to occur and was observed most frequently following ration changes. In several instances the U-tuce was completely plugged with sand. Blockage of the U-tube was slightly more frequent but less severe when the animal received only hay. A further point of interest occurred approximately 14 O P—c r ..' 'UOCJ‘ . c if. I ~ V.rn . LVLMM‘ I § 268 days after the ration was changed from R42 to R21. The animal became slightly bloated and remained in that condition for ' about 24 hours after which spontaneous recovery occurred. Ingesta in the U-tube was extremely frothy in nature and appeared to pass through the tube at more infrequent intervals than was usually observed with ingesta of normal consistency. In general, the animal remained in excellent health until about two weeks following the duodenal collection on once-a-day feeding and the subsequent change to twice-a-day feeding of the all-corn ration. At that time it was noted that the area around the lower cannula began to progressively lose muscle tone and bulge excessively. The animal failed to clean up its feed and eventually refused feed entirely. A change to a hay and grain ration as well as various other treatments failed to alleviate the situation. Outflow from the proximal duodenum through the U-tube'ceased. Body weight and temperature re- mained normal. Condition of the animal, however, steadily declined over a two-week period and death finally resulted. AutOpsy revealed that a portion of the abdominal wall in the area of the incision (slightly posterior and ventral to the lower cannula) had partially herniated and consisted of peritoneum, fibers of the internal abdominal oblique muscle, fascia and skin. There was a rent in the external abdominal oblique muscle. The inner flange of the lower cannula had migrated from 269 the lumen of the duodenum and was lodged in the adjacent abdominal musculature. A tract still existed from the lumen of the duodenum to the cannula but this was nearly occluded by folds of the mucous membrane thus rendering the cannula non- functional. The upper cannula was prOperly within the lumen of the duodenum and was functional. At both openings there were sufficient adhesions between duodenum and peritoneum to prevent any spillage of ingesta into the peritoneal cavity. With the exception of a small amount of fat necrosis, the re- mainder of the abdominal viscera was in excellent condition. Appearance and odor of the reticulo-rumen, omasal, abomasal and intestinal contents was normal. Partition of digestibility In the conventional digestion trial coefficients of total digestion are calculated according to the formula 1&9 x 100, where I equals the average daily intake of nutrients and 0 equals the average daily output of nutrients in the feces. Similarly, coefficients of digestion can be calculated for the upper gut (reticulo—rumen, omasum, abomasum) if the total 24-hour output of nutrients from the upper gut is known and providing the following assumptions are valid: 1. With constant feed intake the dry matter output from the upper gut in 24 hours equals the dry matter in- take in 24 hours. *4 t5 270 2. With constant feed intake the amount of ingesta in the upper gut assumes a constant value. 3. With constant feed intake the output from the upper gut on any given day is representative of and equiva~ lent to the output on any other day. 4. With continuous re—introduction the output of ingesta from the upper gut is equivalent to the passage of ingesta from the upper gut in the intact alimentary tract. In accordance with these assumptions, the total 24-hour output from the proximal duodenum, determined by means of a re—entrant duodenal fistula, was used to determine coeffi- cients of digestibility for the upper gut. Chromic oxide ratios were used as an expedient method of determining total digestibility. Lower gut coefficients were determined by difference. Composition of the corn and alfalfa hay as well as the experimental rations is shown in Appendix Table 7. The alfalfa hay used in these trials was first-cutting hay, cut in the prebud stage and processed through a field crusher. It graded U. S. No. 2 in color, extra leafy and consisted of approxi— mately 8 percent dandelions. Its palatability was excellent. The corn was finely ground. The mineral mix which was fed in conjunction with the hay and/or corn was composed of 2.0 lb. sodium chloride, 1.0 lb. dicalcium phosphate and 2.0 g. cobalt carbonate. Feeding different hayzcorn ratios afforded a com— 271a paratively narrow differential between high and low levels of dry matter while the differentials between high and low levels of the organic and inorganic components were considerably wider. The influence of ration and frequency of feeding on the composition of ingesta passed from the proximal duodenum and of feces is given in Appendix Tables 8 and 9, respectively. The differential between component levels of ingesta and feces with different rations is narrower, with the exception of ether extract, than the differential between component levels of the rations. In fact, the data suggest that the com— position of residues passing from the upper gut assumes a com— paratively constant value which is only in part dependent upon ration composition. Table 14 shows the average daily intake of ration compo- nents. The total ration was readily consumed in all trials. Table 14. Average daily intake of ration components Dry Organic Protein Ether Crude N—free Ration matter matter (Nx6.25) extract fiber extract Ash Cr205 8‘ 8° 8° 8' g’ 8' 8' 8° R1 4040.5 5907.9 451.2 184.5 90.2 5181.9 151.4 10.0 R; 4024.1 5818.5 561.6 165.0 556.2 2756.6 205.8 10.0 R5 4002.5 5659.0 708.9 154.6 664.2 2189.5 504.5 10.0 R4 . 5986.5 5609.5 619.5 115.2 910.2 1764.2 576.8 10.0 271b Dry matter intake was comparable for all rations, varying over a range of only 54 g. The variation of intake between rations for other fractions was much greater. The output of ration components from the duodenum over a z4-hour period is shown in Table 15. The average daily output of ration components in the feces is given in Table 16. Con- siderable variation in output is apparent with different rations and different frequencies of feeding. Since these values are direct measurements of the "indigestible" residues, the coefficients of digestion for the total tract and the upper gut can be calculated accordingly. Coefficients of total digestion are given in Table l7. There was a general Table 15. Output of ration components from the duodenum over a z4-hour period Dry Organic Protein Ether Crude N-free Ration matter matter (Nx6.z5) extract fiber extract Ash 8' 8' 8° 8' 8° 8' 8' R11 1808.9 1466.4 615.2 h15.5 74.7 564.5 542.1 R21 £860.5 2260.0 720.5 257.5 Z90.0 994.9 600.1 R22 5110.6 2525.5 954.0 258.0 288.5 1021.2 586.9 R51 2764.9 L257.1 717.4 190.4 406.8 820.6 527.6 R52 2529.1 182;.8 618.9 165.7 287.5 751.5 506.1 R41 2558.8 1951.2 7&5.4 150.8 407.4 665.8 607.5 R42 2597.8 1985.8 659.1 145.0 447.8 752.4 611.9 272 Table 16. Average daily output of ration components in the feces Dry Organic Protein Ether Crude N-free Ration matter matter (Nx6.25) extract fiber extract Ash Cr203 g. g. g. g. g. g. g. g. Rll 650.2 587.9 156.8 55.2 116.5 501.4 62.5 10.0 R21 1527.2 1151.6 262.7 48.0 297.0 525.7 195.6 10.0 R22 1192.9 1047.4 255.1 54.0 510. 447.0 145.5 10.0 R51 1595.6 1187.5 255.5 57.0 410 5 485.7 206.1 10.0 R52 1148.8 994.5 205.8 55.2 546 5 408.7 154.5 10.0 R41 1495.5 1505.5 228.5 49.6 511.0 515.6 188.0 10.0 R42 1619.0 1400.9 280.7 67.7 489 565.1 218.1 10.0 Table 17. Coefficients of total digestion Dry Organic Protein 'Ether Crude N-free Ration matter matter (Nx6.25) extract fiber extract Ash % % % 2‘6 /'o % 75 R11 85.9 85.0 69.7 82.0 -29.1 90.5 52.6 R21 67.0 70.4 55.2 70.6 11.7 81.0 5.0 R22 70.4 72.6 58.1 66.9 7.6 85.8 29.5 R51 65.5 66.0 64.7 65.4 54.9 76.1 55.5 R52 71.5 75.1 71.0 75.5 47.8 81.5 49.5 R41 62.5 65.8 72.1 56.1 45.8 70.8 50.1 R42 59.4 61.2 65.7 40.2 46.2 68.1 42.1 275 tendency for the extent of digestion to increase with all fractions, except crude fiber, as the proportion of corn in the ration increased. Crude fiber digestibility was decreased with increased amounts of corn. The negative coefficient ob- tained for crude fiber with the all-corn ration may have been a result of the consumption of bedding materials. Twice-a-day feeding tended to increase the coefficients of digestibility for most fractions (excluding those for R4), however, the results were not consistent or great enough to be conclusive. Table 18 shows the coefficients of digestion for the upper gut. Negative coefficients were obtained with all rations for ether extract and ash, thus indicating a con- Table 18. Coefficients of digestion for the upper gut Dry Organic Protein Ether Crude N-free Ration matter matter (Nx6.25) extract fiber extract Ash % 5 % % % % % R11 55.2 62.5 -55.9 -15.? 17.2 82.5 —160.4 321 28.9 40 8 -28.5 -45.? 15.7 65.9 -l9l.6 ' R22 22.? 55.9 —69.9 -58.5 14.2 65.0 —185.2 R51 50.9 59.5 —l.2 -41.5 58.8 62.5 -75.5 R52 41.8 50.7 12.7 -21.6 56.7 65.7 ~66.2 R41 55.8 45.9 11.5 —55.2 55.2 62.5 —61 2 R42 54.8 45.0 19.6 -28.1 50.8 58.5 -62.4 274 siderable addition of these fractions to the ingesta in the upper gut. The additions were most noticable with the high corn-low hay ration. Furthermore, it appears that, as the ash intake increased, the addition of sea to the ingesta decreased accordingly. There was a tendency for ether extract to accumu- late in the ingesta with increasing ether extract intake. Negative coefficients were also obtained with the high-corn rations for protein. Ration 5 appeared to be borderline with reapect to the addition of nitrogen to the ingesta. Positive digestion coefficients for the upper gut were obtained in all cases for dry matter, organic matter, crude fiber and N—free extract, and for protein with R52, R41 and R42. The coefficients for total dry matter and organic matter were highest with the all-corn ration and lowest for the high corn—low hay ration. Values for these fractions with R5 and R4 were not markedly different. Low digestibility of crude fiber was obtained with the high-corn rations. Crude fiber digestion increased as the amount of corn in the ration de- creased. Excluding the value for R1, the digestibilities of N-free extract were quite similar. The influence of twice-a-day feeding on the coefficients of digestion was not clear. In general, lower coefficients were obtained as a result of more frequent feeding for R2 and R4 but higher coefficients were obtained for R5. Coefficients of digestion for the lower gut (intestinal tract) are shown in Table 19. These values indicate that 275 Table 19. Coefficients of digestion for the lower gut Dry Organic Protein Ether Crude N-free Ration matter matter (Nx6.25) extract fiber extract Ash 2 5 2 % % % % Rll 28.7 22.5 105.6 97.7 -46.5 8.5 212.9 321 58.1 29.6 81.5 116.5 -2.0 17.1 196.6 R22 47.7 58.7 128.0 125.2 —6.6 20.8 214.5 R51 52.6 26.5 65.9 104.9 -5.9 15.6 106.8 R52 29.5 22.4 58.5 97.0 -8.9 15.7 115.5 R41 26.7 17.9 60.6 89.5 -11.4 8.5 111.5 R42 24.6 16.2 46.2 68.5 -4.6 9.6 104.5 digestion in the lower gut was increased as the amount of corn in the ration was increased and as the digestibility in the upper gut was decreased. The values for crude fiber are of considerable interest for they indicate an addition or accumu- 1ation of crude fiber in the lower tract. The exact nature of this addition or accumulation is not known. It was pos- sible for the animal to consume wood shavings, however, examination of the ingesta and/or feces for wood shavings residues did not disclose tne presence of these at any time. Again, the animal was not ever seen eating shavings. Protein ether extract and ash values show that these fractions were removed, for the most part, in the lower gut. The compara- ) 276 tively high values for N-free extract for R2 and R5 suggest that perhaps, where hay and corn were fed in combination, larger amounts of corn escaped fermentation in the upper gut by rapidly passing to the intestinal tract. Coefficients of digestion for N~free extract were higher for all rations when the animal was fed twice daily but the influence of twice-a-day feeding on other fractions was less distinct. In general, the coefficients were increased with R2 but were decreased with R5 and R4. The extent of digestion occurring in the upper and lower gut in relation to total digestion is shown in Tables 20 and 21. A considerable addition of both ether extract and ash to the ingesta took place in the upper gut with each of the rations. Total removal of the digestible part of these frac- tions occurred in the lower tract. Similar results were found for the nitrOgenous components with R11, R21, R22 and R51. Some losses of nitrOgen occurred in the upper tract with R52, R41 and R42, however, the most of the nitrogen was removed from the ingesta in the intestinal tract. All of the crude fiber digestion and more than 75 percent of the N-free extract digestion occurred in the upper gut. Additional breakdown of n-free extract took place in the lower gut but there was no further digestion of crude fiber. These values emphasize the role of the upper gut in carbohydrate digestion. Extensive losses occur in the lower part of the tract 277 Table 20. Percentage of total digestion occurring in the upper gut Dry Organic Protein Ether Crude N-free Ration matter matter (Nx6.25) extract fiber extract Ash 2 % % % % % 4 R11 65.8. 75.5 -5l.5 -19.2 58.9 90.9 -504.9 R21 45.2 58.0 ~55.1 —64.8 117.9 78.9 -5865.7 R22 52.5 46.7 —120.2 -87.2 186.4 75.1 —652.0 R51 48.7 59.8 -1.8 -65.5 111.2 82.1 —218.8 R52 58.6 69.4 17.9 -58.7 118.6 80.8 -154.5 R41 57.5 71.9 16.0 -59.2 126.0 88.0 -122.2 R42 58.6 75.5 29.8 -69.9 110.0 85.9 -148.2 Table 21. Percentage of total digestion occurring in the lower gut Dry Organic Protein Ether Crude N-free Ration matter matter (Nx6.25) extract fiber extract Ash 54. 56. 67. 51. 41. 41. (‘7 #ch- C»! \7 (D. % 26.5 4‘600 55.5 2 151. 155. 220. U! H % % 9.1 404. 21.1 5965. 24.9 752. 17.9 518. 19.2 254. 12.0 222. 14.1 248. ‘ 01 (D O x) N 278 even though a substantial amount of the digestible components have been removed from the ingesta prior to reaching this point. Coefficients of digestion for residues entering the lower gut are shown in Table 22. A comparison of these values with the values in Table 17 indicates that much of the protein, ether extract and ash added to the ingesta in the upper gut as well as the protein, ether extract and ash of dietary origin was removed from the ingesta in the lower gut. These fractions accounted for most of the digestion that occurred in the lower tract. N—free extract digestion amount- ed to slightly less than 50 percent for those rations contain— ing corn whereas the coefficients for R41 and R42 were Table 22. Coefficients of digestion for residues entering the lower gut Dry Organic Protein Ether Crude N-free Ration matter matter (Nx6.25) extract fiber extract Ash % 7'6 76 76 5’3 3% /o 'R11 64.1 59.9 77.7 84.4 -56.0 46.6 81.8 R21 .55.6 49.9 65.5 79.8 -2.4 47.4 67.4 R22 61.7 58.5 75.4 79.1 -7.7 56.2 75.2 R51 49.6 46.9 67.2 70.1 -0.9 41.1 g 60.9 R52 50.7 45.4 66.7 V 79.7 -20.6 45.6 69.5 R41 46.4 59.2 68.7 65.7 -6.8 29.1 69.7 R42 57.7 29.5 57 4 55.5 ~9.5 25.1 64.4 279 approximately one-half of this value. The negative coeffi- cients for crude fiber suggest that the addition was not of dietary origin per fig but was an accumulation of residues in the lower gut. PhysiOlOgical effects of different rations Table 25 summarizes the physiological data obtained for the duodenal collections on each ration and frequency of feed- ing. There was a general increase in body weight throughout the experiment. The total increase, however, was only 70 pounds. The differences in weight did not appear great enough to warrant adjustment of the duodenal output on the basis of body weight. Only minor weight changes were noted as a result of the collection itself. Relatively good agreement was ob- tained between total input (feed and water) and total output (feces and urine). Water intake was lowest with R1 and highest with R4. The intakes with the mixed rations were similar with the exception of that for R21. The additional water intake which occurred with this ration was probably due to the relatively high envi- ronmental temperature on the day of c011ection. Fecal excretions for a given ration agreed comparatively well considering the fact that the values were for only 24—hour excretion periods. Urinary excretion appeared to be influenced to a certain 000 H00 000 000 08a 000 .. 1.0080 0000000850 00000 0808 we mm 04 mm «0 0m 0&0 A.:Hav wsapmm Mo coapmnsm .0 00 40 0e 00 00 80 00a A.eaav 000500 00000 0808 mm 0.00 H.00 0.00 8.00 8.00 0.00 0.00 1.000 emeaos 00000 0.00 0.00 0.00 0.00 0.0 0.0 0.0 1.000 00000620 00000 8.0 0.0 0.4 0.0 0.4 0.0 0.0 1.0000 090000 00003 0.00 0.00 0.00 0.00 0.00 0.00 0.0a 1.000 000000 0000 o o 0: mu 0: 8+ m+ A.hav omamno 900003 008 008 008 088 000 008 000 1.000 000003 8000 000 000 000 000 000 Ham Ham coapooaaoo Hmcouosp £000 90% 0900 Hmoawoaoammnd no mamaadm .nN magma 281 extent by water intake and by the frequency of feeding. In- creased water intake was usually accompanied by an increase in urinary output although the differences in urinary excre- tion were not always commensurable with the differences in water intake. Urinary excretion was also increased as a re— sult of once—a-day feeding. The patterns of eating and rumination (Figures 19, 20, 21, 22, 25, 24, 25) for each collection are summarized in Table 25. The actual time Spent eating was considerably longer with all corn and slightly longer with all hay fed once daily than with the mixed rations fed according to the same schedule. A reduction, which became less as the ration changed from high-corn to all hay, in the time spent eating was found when the rations were fed twice daily. The span of time re— quired to consume the ration was markedly reduced by dividing the ration and feeding it twice daily in two equal portions. With more frequent feeding of smaller amounts the animal con- tinuously ate until the ration was cleaned up whereas with the single feeding of a larger amount eating periods were inter— mittant and interspersed by drinks of water. The duration of eating for a given frequency of feeding was similar for each ration with the exception of R11. Eating behaviour for this ration was characterized by a number of short periods spread over approximately 14 hours. The amount of time spent ruminating was influenced by 282 ration but not by frequency of feeding. Exceptionally good agreement was obtained between collections for a given ration. Rumination was completely abolished by feeding an all-corn ration and was reduced by about one-third by feeding a high corn-low hay ration. The times spent ruminating on the high- hay and all-hay rations were similar. Slightly higher values were obtained for the high-hay ration. Effect of ration and frequency of feedigg on thegpattern of duodenal flow Passage of ingesta from the proximal duodenum occurred as gushes and trickles at irregular but relatively frequent intervals throughout the collections. Flow of ingesta, though variable in amount, occurred in every sampling period with the exception of one period with R21 and two periods with R41. The patterns of flow for eaCh ration and frequency of feeding are presented in Figures 19 through 25. The discrepancies in flow patterns obtained by the re-entrant duodenal fistula technique have been discussed in the preliminary section and thus will not be pursued further here. Excluding R21 the general patterns of flow were similar for all rations with a given frequency of feeding. Fluctuat- ing variations were apparent for all rations, however, the amplitude of the variations was greatest for the high corn— 1ow hay ration. The maximum flow of ingesta for a given 15- minute period with this ration was 2560 m1. whereas the maximum Amcapmm .m “coapwcaasn .mv 80000000 000 0000 0000000 0o 3000 000 so 000 00 000000 .ma onsmam 284 VN ON m. m_ AmIVm2+P . v. N_ O. m w ¢ N 00? TOOm ICON. I009 IOOON UJ =E- (WW)3WOWOA :-_ 441—8 Amcapmm .m ”coapwcaasn . ascmoosv 039 8029 mummwca mo 30H“ map so Hum no 9009mm .00 000008 $5. 02: VN NN ON m. w_ v_ N_ O_ m w v N 00¢ loom ICON. IOO®_ am IOOON (7W) 3W070A Amsauwo .m ”coapmcaada .mv 80200000 0gp 802% 0000000 mo soda 03p no mum no 0009mm .HN onsmah mm AmIVerH v_ N_ O_ m w v N 0N NN ON m. w_ loom. IOOON 3W070A (1w) 289 chapmm .m ”coapmsaasn .mv 80c00000 map 809% mummmsa mo 30am on» so Hnm no uommwm .nu mnzwam 290 10100208 0 VN NN ON w_ m_ S O. : c c = _L c c: c = C = = : = = :2 __ = ===== 00¢ loom IOON_ IOO®_ IOOON (7W) BWHWOA chap00 .m “coau0caasu .mv 30000000 0gp Bonn 0000000 80 soak 030 no mam Mo pommhm .00 mnswah AmIv mErk VN NN ON m_ w. v. N_ O_ m w v N TOON_ room_ IOOON (7W) BWOWOA chapwm .m “coapmcaasn .mv ascmwosw mnp 509w mummwsa no sea“ map so me mo pommmm .wu madman VN 294 NN ON m 0 E5 “:2; S N_ O_ IOO®_ IOOON (7W)3WDWOA Amqapwm .m ”coapmcaazn .mv essmuozo map Bong mummmca go zoau map so N¢m mo poouwm .nu madman 296 AmIv mZ_F VN NN ON m_ m_ V_ N_ O_ w 0 v N 00? OOm IOO§ IOOO_ IOOON jglélffizfifillfim __ __ :c 5;: (I (1W) 3WDWOA 297 with any of the other rations was 1700 ml. Flow during all collections was initially high and declined thereafter with the exception of R21 which exhibited a terminal increase. The collection with R21 was the only collection which fol- lowed this trend. More frequent feeding had the general effect of lowering the initial flow, increasing the persis- tency of flow and decreasing the amplitude of the variations of flow. Some rhythmicity of flow is suggested by the flow patterns but it is difficult to draw any definite conclusions in this regard. Effect of ration and frequency of feeding on the pH of duodenal ingesta The pH of ingesta passing from the duodenum for each col- lection (Appendix Tables 10 through 16) is summarized in Figure 26. pH was remarkably constant with a given ration and fre- quency despite large variations in flow. Oscillations of pH were somewhat greater with the mixed rations than with the corn or hay ration, however, the maximum pH change for any ration was only 1.0 pH units. The only exception to this was a single pH value of 5.55 obtained with 351- ‘There did not appear to be any absolute relationship between flow and pH. High flow volumes were accompanied by relatively high pH values as well as low pH values. The same was true for low flow volumes. Only minor differences in pH were observed between rations and frequencies. The mean pH of ingesta for Figure 26. Effect of ration and frequency of feeding on the pH of ingesta passed from the duodenum 3.. 2- I4 N 04 I I 3.. 2a I -4 3a 2.. I4 3.. 2—1 I- 3.. 2- I -4 3.. 2- 299 -RI| R2| R22 RBI R32 R4I R42 WW llTTlTIIITlIIITFIITIl 4 6 8 IO I2 I4 l6 I8 202224 TIME(HR.) ‘~ Hui-3*.“ ' n...L—_.—— 300 each collection was as follows: Rll, 1.92; R21, 1.86; R22, 2.07; R51, 1.95; R52, 1.97; R41, 2.07; R42, 1.80. If fre- quency is disregarded and the values for rations are averaged together then differences between collections become even less (R1, 1.92; R2, 1.96; R5, 1.96; R4, 1.95). It is of in- terest that the all-corn and all-hay rations had a slightly lower average pH than the mixed rations. Effect of ration and frequency of feeding on the passage of ingesta from the duodenum The influence of ration and frequency of feeding on the volume and composition of ingesta passed from the duodenum is shown in Appendix Tables 10 through 16. The quantities of total ingesta, dry matter, organic matter and ash which were passed during successive lS-minute periods are presented in Tables 24 through 50. Noticeable differences were found be- tween rations and frequencies in the total amount of ingesta passed during a digestion cycle (24 hours). The total volumes passed were 54.8 1. for Rll, 79.9 1. for R21, 76.4 1. for R22, 65.8 1. for R51, 65.2 1. for R52, 70.8 1. for R41 and 67.7 1. for R42. Marked fluctuations in flow during the course of the collections were observed for all rations and afrequencies. The mean volume and range of ingesta passed from the duodenum per lS-minutes was 571 ml. (range, 10-1560 ml.) for R11, 855 ml. (range, 0-2560 ml.) for R21, 796 ml. (range, 60-2165 ml.) for R22, 685 ml. (range, 150-1700 ml.) for 351, 501 Table 24. Effect of R11 on the passage of total ingesta, dry matter, organic matter and ash from the duodenum Time Volume Dry matter Organic matter Ash (min.) (ml.) (g.) (g.) (g.) 15 1040 50.1 25.4 4. 50 670 18.6 15.5 5. 45 510 15.0 12.0 5. 1 hr. 720 22.8 18.4 4. 15 860 24.5 18.9 5. 50 1540 55.6 27.7 7. 45 1200 55.5 26.9 6 2 hr. 1690 55.9 44.6 9 15 1500 41.6 55.7 7 50 750 20.5 16.0 4 45 200 5.0 5.8 1 . 5 hr. 250 6.2 4.8 l 15 795 21.2 17.5 4 50 770 20.4 16.6 5. 45 585 15.5 12.4 5. 4 hr. 400 10.7 8.5 2. 15 270 7.0 5.5 1 50 790 19.8 15.9 5. 45 1020 26.7 21.6 5. 5 hr. 740 20.7 17.0 5. 15 995 51.2 25.6 5. 50 890 28.8 25.9 4. 45 500 10.0 8.5 l 6 hr. 660 25.4 19.8 5. 15 820 29.4 25.0 4 50 540 12.2 10.5 1 45 595 15.2 11.0 2. 7 hr. 685 24.2 20.5 5 15 550 12.7 10.6 2. 50 140 6.0 5.2 O. 45 75 5.2 2.7 O 8 hr. 505 12.9 11.2 1. q$mp bmbm whoa mwmm mpwo mmeo moo» uomm 502 Table 24. (Continued) Time Volume Dry matter Organic matter Ash (min.) (ml.) (g.) (g.) g.) 15 545 21.6 18.5 5.1 50 450 17.2 14. 2.7 45 260 10.7 9.1 1.6 9 hr. 545 14.2 12.5 1.9 15 260 11.7 10.5 1.4 50 550 22.5 19.2 5.1 45 965 40.5 55.0 7.2 10 hr. 1560 66.9 59.0 8.1 15 770 57.2 52.9 4.5 50 1195 56.1 49.2 6.8 45 740 50.0 26.1 5.9 11 hr. 400 16.0 .15.8 2.5 15 275 10.5 8.9 1.6 50 455 15.9 15.4 2.6 45 780 28.6 24.0 4.5 12 hr. 590 16.1 14.0 2.1 15 565 15.8 14.2 1.7 50 490 18.2 15.7 2.4 45 710 25.8 21.7 4.1 15 hr. 950 55.0 29.8 5.2 15 715 25.7 21.8 5.9 50 770 50.0 25.5 4.8 45 580 22.1 19.4 2.7 14 hr. 595 15.1 12.9 2.2 15 620 20.8 17.5 5.5 50 740 24.1 20.0 4.2 45 790 26.2 22.2 4.0 15 hr. 725 24.6 20.0 4.5 15 825 50.4 26.5 5.8 50 250 8.9 7.6 1.5 45 590 14.5 12.2 2.1 16 hr. 560 12.2 10.5 1.9 503 Table 24. (Continued) Time Volume Dry matter Organic matter Ash (min.) (ml.) (g-) (g.) (g-) 15 405 14.5 12.5 2.2 50 10 0.4 0.5 0.1 45 505 10.0 8.6 1.4 17 hr. 880 51.9 26.7 5.5 15 490 16.5 15.9 2.6 50 510 10.6 8.7 1.9 45 250 7.8 6.5 1.5 18 hr. 420 12.9 10.2 2.7 15 475 15.7 15.5 2.2 50 200 6.4 5.4 1.0 45 550 12.9 11.2 1.7 19 hr. 495 18.2 15.9 2.5 15 490 17.5 15.5 2 2 50 290 11.0 9.6 1.4 45 560 12.6 10.5 2 5 20 hr. 650 21.5 17.5 4.2 15 480 15.8 10.8 5.0 50 580 17.5 15.5 5.8 45 590 12.5 9.9 2.7 21 hr. 585 11.5 9.1 2.5 15 410 11.2 8.6 2.6 50 420 11.1 8.5 2.6 45 760 20.7 16.2 4.6 22 hr. 490 12.9 9.8 5.1 15 475 11.4 8.5 5.0 50 400 10.0 7.6 2.4 45 505 8.7 6.8 1.9 25 hr. 170 5.0 5.9 1.1 15 590 10.2 7.9 2.5 50 550 8.8 6.7 2.1 45 470 15.5 10.6 5.0 24 hr. 525 15.2 12.0 5.5 504 Table 25. Effect of R21 on the passage of total ingesta, dry matter, organic matter and ash from the duodenum Time Volume Dry matter Organic matter Ash (min.) (ml.) (g.) (g.) (g.) 15 520 14.0 11.5 2.5 50 470 15.7 11.5 2.2 45 1120 27.4 25.0 4.4 1 hr. 1150 27.4 25.1 4.2 15 905 22.0 18.5 5.7 50 1050 29.8 25.5 4.5 45 270 6.9 5.8 1.1 2 hr. 195 5.0 4.0 0.9 15 190 4.5 5.7 0.8 50 680 18.2 15.0 5.1 45 540 16.9 14.4 2.4 5 hr. 880 25.9 21.5 4.6 15 850 24.1 20.4 5.7 50 620 16.7 14.0 2.7 45 240 6.7 5.6 1.1 4 hr. 450 15.8 11.6 2.2 15 1200 58.5 52.0 6.4 50 1110 57.0 51.0 6.0 45 1460 47.2 59.9 7.2 5 hr. 690 20.6 17.6 5.0 15 970 50.8 26.0 4.8 50 750 25.6 19.9 5.8 45 850 27.4 25.6 5.9 6 hr. 965 54.6 29.9 4.6 15 240 8.8 7.6 1.2 50 590 21.1 18.5 2 6 45 980 54.2 29.0 5.1 7 hr. 1160 45.5 57.6 5.7 15 755 25.1 21.4 5.6 50 290 10.6 9.4 1.2 45 190 6.1 5.1 1.0 8 hr. 625 27.4 24.5 5.2 505 Table 25. (Continued) Time Volume Dry matter Organic matter Ash (min.) (ml.) (g.) (g.) (g.) 15 1510 61.5 55.7 7.6 50 880 59.6 54.7 4.9 45 750 50.9 27.2 5.7 9 hr. 145 5.9 5.5 0.7 15 995 42.6 57.4 5.1 50 1280 55.4 46.7 6.7 45 1075 49.9 44.1 5.8 10 hr. 1210 48.0 42.4 5.7 15 1155 44.2 58.5 5.7 50 215 7.9 6.8 1.1 45 1060 45. 40.5 5.1 11 hr. 750 50.7 27.1 5.6 15 1520 65.0 56.1 6.9 50 1050 45.2 58.1 5 O 45 -— -- -- _- 12 hr. 200 6.2 5.2 0.9 15 725 22.2 18.8 5.4 50 660 21.9 18.7 5.2 45 980 54.7 50.1 4.6 15 hr. 1110 44.7 59.5 5.2 15 855 50.5 26.5 4.1 50 750 25.7 20.5 5.4 45 540 15.5 15.1 2.4 14 hr. 845 27.8 24.0 5.8 15 870 26.7 22.7 4.0 50 100 5.7 5.5 0.4 45 1085 59.5 54.0 5.5 15 hr. 1500 42.9 56.8 6.1 15 665 18.2 15.1 5.0 50 640 25.0 19.8 5.2 45 620 21.2 18.0 5.2 16 hr. 590 20.1 17.4 2.8 506 Table 25. (Continued) Time Volume Dry matter Organic matter Ash (min.) (ml.) (g.) (g-) (g.) 15 855 50.8 26.1 4.8 50 2560 84.5 72.2 11.8 45 1520 51.2 44.5 6.7 17 hr. 190 8.0 7.2 0.8 15 560 17.5 15.2 2.4 50 580 16.9 14.5 2.6 45 795 50.8 26.7 4.1 18 hr. 1210 41.5 55.1 6.5 15 560 8.8 7.1 1.7 50 1210 29.2 24.1 5.0 45 665 15.0 12.1 2.9 19 hr. 515 11.4 9.2 2.2 15 925 24.4 20.6 5.7 50 1075 24.9 21.5 5.8 45 1480 56.0 29.5 6.5 20 hr. 1600 54.6 47.5 7.0 15 12220 40.5 55.5 5.1 50 450 12.7 10.8 2.0 45 750 19.2 16.0 5.1 21 hr. 1120 50.0 25.2 4.8 15 1680 47.5 59.0 8.6 50 1125 29.8 25.2 4.6 45 850 19.1 15.7 5.5 22 hr. 1640 45.6 56.4 7.2 15 1440 59.6 54.4 5.2 50 1075 24.9 20.8 4.2 45 800 17.0 14.2 2.8 25 hr. 1040 21.5 17.5 4.0 15 575 8.6 7.4 1.2 50 550 15.4 11.6 1.8 45 1210 55.6 29.9 5.7 24 hr. 580 10.8 9.0 1.8 507 Table 26. Effect of R22 on the passage of total ingesta, dry matter, organic matter and ash from the duodenum Time Volume Dry matter Organic matter Ash (min.) (ml.) (g-) (go) (g-) 15 1555 54.5 47.7 6.6 50 2165 79.2 68.6 10.8 45 1540 56.0 49.5 6.7 1 hr. 1010 58.6 55.2 5.5 15 1620 62.7 55.6 9.1 50 590 24.4 21.4 5.5 45 820 58.4 55.6 4.7 2 hr. 1140 50.4 45.9 6.4 15 450 17.6 15.1 2.5 50 880 54.2 29.7 4.6 45 910 55.6 50.8 4.8 5 nr. 950 56.2 50.8 5.4 15 595 25.7 20.5 5.5 50 950 57.7 51.7 6.0 45 480 17.9 15.5 2.5 4 hr. 120 4.2 5.5 0.7 15 940 44.7 59.2 5.4 50 1410 61.2 55.5 7.9 45 990 42.5 55.7 6.5 5 hr. 740 51.4 26.8 4.6 15 850 29.1 24.1 5.0 50 505 18.2 15.0 5.2 45 1540 55.7 45.8 7.8 6 hr. 1615 62.0 55.9 8.1 15 755 26.7 22.9 5.8 50 995 58.0 52.9 5.1 45 565 19.2 15.6 5.6 7.hr. 485 15.6 12.6 5.1 15 590 12.4 10.5 2.2 50 740 22.9 18.9 4.0 45 770 24.9 21.7 5.2 8 hr. 280 8.4 7.4 1.1 508 Table 26. (Continued) Time Volume Dry matter Organic matter Ash (min.) (ml.) (s-) (g-) (g-) 15 140 4.1 5.5 0.6 50 860 27.0 21.9 5.1 45 650 25.2 20.2 5.1 9 hr. 955 57.1 50.8 6.5 15 760 29.5 24.2 4.9 50 655 22.1 18.0 4.2 45 510 16.0 12.9 5.2 10 hr. 845 27.6 22.5 5.5 15 920 54.9 29.4 5.4 50 550 12.0 9.9 2.1 45 700 25.9 21.6 4.5 11 hr. 915 57.0 51.2 5.8 15 1560 54.5 46.0 8.5 50 1210 54.6 47.0 7.6 45 800 55.9 29.2 4.7 12 hr. 550 11.5 9.5 2.0 15 600 18.9 15.4 5.5 50 970 52.5 26.9 5.5 45 855 27.1 22.2 4.9 15 hr. 415 15.4 11.1 2.2 15 545 10.4 8.4 2.0 50 780 24.9 20.8 4.1 45 995 56.5 50.7 5.9 14 hr. 690 26.4 22.6 5.9 15 585 15.5 11.5 2.0 50 870 26.9 22.1 4.8 45 545 16.4 15.2 5.2 15 hr. 495 14.4 11.8 2.5 15 570 15.0 11.2 1.7 50 60 2.0 1.8 0.5 45 540 12.6 11.1 1.5 16 hr. 1495 57.1 50.2 6.9 509 Table 26. (Continued) Time Volume Dry matter Organic matter Ash (min.) (ml.) (g-) (go) (go) 15 1220 46.1 59.4 6.7 50 1550 47.5 40.2 7.5 45 910 51.4 26.8 4.6 17 hr. 500 16.2 15.9 2.4 15 490 15.6 15.1 2.6 50 620 21.4 18.7 2.7 45 800 29.0 24.7 4.5 18 hr. 805 29.9 24.6 5.2 15 900 51.1 26.9 4.2 50 800 25.6 21.5 4.1 45 1000 55.2 50.5 4.9 19 hr. 755 25.8 21.5 4.5 15 965 55.6 51.1 4.5 50 290 11.1 9.4 1.7 45 1100 59.6 55.5 6.5 20 hr. 675 25.4 19.7 5.7 15 620 21.5 18.4 2.9 50 190 6.8 5.8 1.0 45 545 19.6 16.5 5.1 21 hr. 1265 51.4 45.9 7.5 15 1520 52.8 44.4 8.5 50 1570 48.9 40.4 8.5 45 255 7.7 6.6 1.1 22 hr. 280 9.2 7.8 1.4 15 440 14.6 12.4 2.2 50 925 55.5 29.0 4.6 45 1195 45.6 56.1 7.7 25 hr. 1100 56.5 51.0 5.5 15 260 7.9 6.6 1.5 50 660 21.5 18.2 5.5 24 hr. 1240 46.5 59.5 7.2 510 Table 27. Effect of R51 on the passage of total ingesta, dry matter, organic matter and ash from the duodenum Time Volume Dry matter Organic matter Ash (min.) (ml.) (g.) (g.) (g.) 15 705 25.8 27.6 4.2 50 1415 51.9 65.5 8.9 45 1500 75.1 64.4 8.7 1 hr. 1700 115.8 104.6 11.2 15 1070 69.5 61.6 7.7 50 820 45.5 58.0 5.6 45 770 55.0 50.8 5.1 2 hr. 995 58.8 52.5 6.6 15 655 26.6 22.5 4.5 50 280 8.5 6.9 1.7 45 410 12.2 9.7 2.5 5 hr. 500 15.8 11.1 2.9 15 790 25.4 20.6 4.7 50 960 55.8 27.9 5.9 45 1120 58.8 51.5 7.5 4 hr. 1090 57.0 50.1 7.5 15 510 17.1 15.5 5.6 50 945 52.1 25.2 6.9 45 1050 55.5 27.8 7.5 5 hr. 895 51.1 24.4 6.5 15 1140 46.5 57.9 8.4 50 610 25.9 21.5 4.5 45 250 8.1 6.4 1.6 6 hr. 550 17.2 15.6 5.7 15 975 55.7 28.7 7.0 50 980 59.2 51.7 7.6 45 715 45.5 27.5 4.8 7 hr. 455 20.6 17.8 2.8 15 420 16.5 15.4 5.1 50 1165 55.1 46.7 7.9 45 1540 82.5 72.0 10.5 8 hr. 920 64.7 57.7 7.0 511 Table 27. (Continued) Time Volume Dry matter Organic matter Ash (min.) (ml.) (g-) (g-) (g-) 15 1510 96.0 85.5 10.5 50 280 19.6 16.9 2.7 45 215 8.8 7.5 1.5 9 hr. 950 41.0 54.4 6.5 15 715 55.8 28.9 4.9 50 690 55.0 28.8 4.5 45 280 11.7 9.5 2.2 10 hr. 270 10.5 8.7 1.9 15 410 15.8 12.8 5.0 50 750 28.8 25.4 5.5 45 1200 51.8 45.2 8.5 11 hr. 910 45.1 58.6 6.9 15 895 45.1 57.1 6.1 50 515 25.8 20.6 5.2 45 205 8.4 6.8 1.6 12 hr. 520 19.9 15.0 5.9 15 765 29.6 24.6 5.1 50 1040 45.8 57.1 6.7 45 900 40.4 54.1 6.5 15 hr. 150 5.5 4.6 0.7 15 310 10.9 8.7 2.5 50 1015 58.2 51.8 6.9 45 1455 61.5 51.5 9.9 14 hr. 660 27.7 25.2 4.6 15 950 40.1 55.4 6.7 50 455 19.9 16.8 2.9 45 150 4.5 5.5 0.8 15 hr. 580 20.9 17.6 5.1 15 720 25.6 21.1 4.5 50 780 29.8 25.5 4.6 45 620 22.9 19.0 4.2 16 hr. 290 10.0 8.5 1.7 512 Table 27. (Continued) Time Volume Dry matter Organic matter Ash (min.) (ml.) (g-) (g-) (g-) 15 200 6.7 5.4 1.5 50 500 9.1 7.5 1.7 45 650 20.2 16.4 5.7 17 hr. 1040 56.9 51.5 5.6 15 665 25.5 21.2 4.2 50 500 20.5 17.4 5.0 45 150 4.1 5.5 0.9 18 hr. 205 6.8 5.5 1.5 15 600 21.5 17.7 5.7 50 820 54.2 29.0 5.2 45 685 52.7 28.2 4.5 19 hr. 745 55.1 28.5 4.6 15 550 14.1 12.0 2.1 50 570 21.2 17.7 5.5 45 560 19.5 16.6 2.9 20 hr. 1090 45.4 56.4 7.0 15 840 59.2 55.8 5.5 50 700 55.7 51.2 4.8 45 500 25.1 22.0 5.2 21 hr. 520 10.6 8.8 1.9 15 850 51.8 26.0 5.5 50 580 11.9 10.0 2.0 45 570 20.5 17.2 5.1 22 hr. 770 56.8 51.7 4.8 15 240 10.0 8.5 1.6 50 200 6.1 4.9 1.2 45 710 21.7 17.8 5.9 25 hr. 500 8.9 7.2 1.7 15 560 21.7 18.5 5.5 50 850 41.8 56.6 5.2 45 270 10.4 8.6 1.8 24 hr. 170 5.1 4.2 1.0 515 Table 28. Effect of R52 on the passage of total ingesta, dry matter, organic matter and ash from the duodenum Time Volume Dry matter Organic matter Ash (min.) (ml.) (go) (g-) (g-) 15 200 6.8 5.8 1.0 50 715 25.0 21.1 4.2 45 1250 44.4 57.1 7.4 1 hr. 1665 75.5 62.9 10.5 15 655 54.9 29.7 5.1 50 645 29.5 25.2 4.5 45 650 24.9 21.5 5.4 2 hr. 805 28.4 25.5 4.8 15 900 29.8 25.5 4.5 50 190 4.9 5.9 1.0 45 400 11.0 9.0 2.0 5 nr. 760 22.2 17.6 4.6 15 850 27.5 22.4 5.2 50 610 20.5 16.8 5.7 45 450 14.6 11.8 2.7 4 hr. 580 55.9 29.6 4.2 15 90 5.4 2.8 0.6 50 860 57. 51.6 5.7 45 990 59.7 55.5 6.4 5 hr. 990 59.9 55.5 6.9 15 640 26.1 22.5 5.8 50 580 16.2 15.4 2.7 45 550 19.1 15.5 5.8 6 hr. 810 29.7 24.4 5.7 15 845 55.5 28.5 5.1 50 660 26.9 22.4 4.6 45 885 45.6 57.4 6.7 7 hr. 595 25.9 21.5 4.5 15 650 29.8 25.4 4.2 50 200 7.5 6.1 1.4 45 1200 60. 51.4 8.6 8 hr. 1000 60.5 51.8 8.1 514 Table 28. (Continued) Time Volume Dry matter Organic matter Ash (min.) (ml.) (g.) (g.) g.) 15 690 58.6 55.8 4 50 550 24.5 21.5 5. 45 595 17.7 15.0 2. 9 hr. 75 2.7 2.1 0. 15 490 20.7 17.8 2. 50 915 55.0 29.9 5. 45 950 58.5 52.4 6. 10 hr. 1190 54.5 45.1 9. 15 1090 51.7 45.1 6. 50 190 7.7 6.8 O. 45 470 18.0 15. 2. 11 hr. 880 57.5 55.0 4 15 955 59.5 54.1 5. 50 1140 46.1 40.5 6. 45 500 15.2 11.6 1. 12 hr. 255 7.7 6.7 1. 15 670 21.8 18.9 5 50 600 20.2 17.6 2. 45 785 27.8 25.9 4. 15 hr. 650 25.6 20.7 2. 15 110 2.9 2.2 O. 50 555 18.7 16.2 2. 45 505 16.2 14.0 2. 14 hr. 890 50.1 25.0 5. 15 755 26.0 21.0 4. 50 950 40.0 54.6 5. 45 150 4.4 5.7 O. 15 hr. 520 18.5 15.6 2. 15 1010 55.9 28.5 5. 50 880 52.7 27.4 5 45 965 55.0 29.2 5. 16 hr. 1120 41.9 54.6 7. Q©$Q 003$“) NIfiCD-Q CONGO 003043 UHb£OU1 (Ob—‘00 070300 515 Table 28. (Continued) Time Volume Dry matter Organic matter Ash (min.) (ml.) (g-) (g.) (g-) 15 550 11.5 9.1 2.2 50 660 17.2 14.1 5.4 45 550 15.9 11.2 2.5 17 hr. 470 15.4 11.0 2.5 15 580 17.9 14.5 5.5 50 565 14.6 12.5 2.5 45 160 5.8 5.0 0.9 18 hr. 200 4.4 5.5 1.0 15 645 16.4 15.9 2.8 50 270 6.8 5.4 1.4 45 800 24.8 19.9 4.9 19 hr. 655 22.7 18.7 5.7 15 520 11.4 9.8 1.6 50 680 21.6 17.6 4.5 45 855 50.4 25.6 4.8 20 hr. 1150 52.7 44.7 7.9 15 1150 51.9 45.6 8.5 50 445 21.5 18.1 5.4 45 565 11.2 8.8 2.5 21 hr. 625 16.8 15.8 5.0 15 490 11.5 8.4 2.9 50 415 10.1 7.9 2.2 45 770 21.4 17.4 4.0 22 hr. 455 12.2 9.8 2.6 15 590 10.1 7.8 2.5 50 170 4.0 5.5 0.7 45 285 7.1 5.6 1.7 25 hr. 760. 21.4 17.5 4.0 15 1575 45.5 58.0 7.6 50 1550 65.9 56.8 9.5 45 715 26.2 21.4 5.1 24 hr. 515 10.5 8.5 2.0 516 Table 29. Effect of R41 on the passage of total ingesta, dry matter, organic matter and ash from the duodenum Time Volume Dry matter Organic matter Ash (min.) (ml.) (g.) (g.) (g.) 15 1110 47.7 42.6 5.6 50 1075 51.1 45.0 8.1 45 645 55.5 27.2 6.5 1 hr. 1610 82.0 65.5 16.4 15 1100 59.5 49.5 10.2 50 1425 66.6 55.7 11.0 45 1055 40.0 52.2 8.1 2 hr. lino 54.9 29.8 4.8 15 880 28.1 21.8 6.5 50 1520 56.4 26.5 9.9 45 420 10.6 7.4 5.2 5 hr. 580 14.5 11.1 5.1 15 640 15.2 11.0 4.2 50 1170 27.9 20.2 8.1 45 980 50.1 25.1 6.9 4 hr. 1700 55.4 40.8 12.1 15 650 18.2 15.7 4.5 50 740 17.0 15.0 4.1 45 550 11.7 9.4 2.6 5 hr. 710 15.4 12.4 5.1 15 1200 25.8 17.8 7.9 50 945 20.0 16.0 5.6 45 810 16.1 12.2 5.6 6 hr. 740 16.4 14.7 1.8 15 700 15.5 11.0 4.6 50 450 9.5 6.4 5.1 45 1190 25.0 16.1 7.5 7 hr. 1150 25.2 18.6 6.7 15 1000 27.1 21.2 5.9 50 1025 28.1 21.2 7.0 45 490 12.4 8.8 5.6 8 hr. 865 21.9 18.0 5.9 517 Table 29. (Continued) Time Volume Dry matter Organic matter Ash (min.) (ml.) (g-) (g.) (g.) 15 565 9.9 8.0 1.8 50 480 15.5 11.4 1.9 45 810 20.6 17.8 2.8 9 hr. 1160 59.1 50.5 8.6 15 1000 29.7 25.8 5.9 50 680 21.5 17.5 5.5 45 250 8.2 6.8 1.4 10 hr. 840 27.9 22.9 5.0 15 650 18.7 15.8 4.9 50 750 22.9 18.8 4.1 45 260 8.9 8.0 0.8 11 hr. 500 24.5 21.7 2.9 15 -— -- -- -- 50 1050 48.6 45.0 5.7 45 715 25.2 20.4 4.9 12 hr. 560 24.4 20.6 5.8 15 580 18.6 16.4 2.4 50 790 41.4 56.7 5.1 45 550 29.2 25.5 5.7 15 hr. 680 51.4 25.5 5.9 15 490 22.6 18.6 4.1 50 880 47.2 59.9 7.7 45 550 18.1 14.9 5.1 14 hr. 1545 65.9 54.5 12.2 15 1610 66.2 55.6 12.6 50 595 24.6 20.1 4.8 45 710 26.2 20.7 5.5 15 hr. 1125 41.7 55.5 8.2 15 1450 54.4 42.9 11.5 50 415 17.4 14.5 5 O 45 -- -- -— _- 16 hr. 515 8.4 7.5 0.9 518 Table 29. (Continued) Time Volume Dry matter Organic matter Ash (min.) (m1-) (g-) (g«) (g-) 15 260 11.5 9.5 2.1 50 585 20 5 16.0 4.5 45 680 25.9 20.5 5.4 17 hr. 610 24.6 20.1 4.5 15 640 25.4 20.1 5.5 50 515 12.5 10.5 2.0 45 570 15.0 10.2 2.7 18 hr. 420 12.2 9.2 5.0 15 605 17.5 14.5 2.8 50 565 11.5 9.1 2.5 45 590 17.8 14.6 5.2 19 hr. 900 40.1 52.4 7.7 15 1290 47.2 58.5 8.9 50 570 12.1 10.5 1.8 45 480 15.5 12.9 2.5 20 hr. 545 14.1 11.4 2.7 15 650 27.8 24.1 5.6 50 880 51.0 26.1 4.8 45 655 21.6 18.5 5.1 21 hr. 450 15.8 11.8 2.1 15 770 25.7 20.0 5.8 50 855 25.7 18.5 5.5 45 915 25.7 21.8 5.7 22 hr. 775 21.2 17.8 5.5 15 410 15.8 12.0 1.9 50 460 18.5 15.4 5.1 45 710 25.0 20.0 5.1 25 hr. 850 21.8 16.2 5.5 15 555 14.8 11.5 5.5 50 775 20.6 16.0 4.9 45 560 15.6 11.8 5.8 24 hr. 550 9.4 7.9 1.5 519 Table 50. Effect of R42 on the passage of total ingesta, dry matter, organic matter and ash from the duodenum Time Volume Dry matter Organic matter Ash (min.) (ml.) (g.) (g.) (g.) 15 880 42.2 56.4 5.6 50 960 42.5 56.5 6.1 45 545 29.8 25.5 4.5 1 hr. 750 56.8 50.2 6.5 15 820 51.5 25.5 6.0 50 1010 57.8 52.0 5.8 45 1255 44.8 57.8 7.0 2 hr. 785 51.1 26.7 4.5 15 680 27.5 25.7 5.8 50 1110 57.0 51.5 5.7 45 940 55.8 28.0 5.9 5 hr. 855 55.7 29.2 4.5 15 900 55.8 27.5 6.6 50 220 6.8 5.5 1.5 45 670 18.2 15.7 4.6 4 hr. 1100 27.9 21.2 6.7 15 1070 51.6 25.4 6.1 50 620 21.5 18.4 5.0 45 660 26.9 21.9 5.1 5 hr. 875 51.0 25.0 6.0 15 250 6.5 4.8 1.4 50 1290 56.5 28.5 8.1 45 510 19.7 16.4 5.5 6 hr. 1140 51.4 42.9 8.6 15 965 59.8 54.5 5.5 50 495 17.2 15.5 5.7 45 850 50.5 24.5 6.1 7 hr. 750 25.5 20.8 4.8 15 995 40.5 55.1 5.2 50 960 41.8 54.1 7.7 45 510 20.7 16.7 4.0 8 hr. 550 12.0 9.4 2.7 520 Table 50. (Continued) Time Volume Dry matter Organic matter Ash (min.) (ml.) (s-) (g-) (g-) 15 160 7.2 5.8 1.5 50 1550 66.2 57.0 9.2 45 815 54.8 50.4 4.4 9 hr. 700 55.0 27.7 5.4 15 400 19.2 16.2 2.9 50 1190 59.4 29.5 10.0 45 890 51.9 25.9 6.1 10 hr. 970 42.9 55.9 9.0 15 1050 48.0 41.0 7.1 50 785 29.6 25.2 6.4 45 1150 44.8 58.5 6.2 11 hr. 115 5.5 2.9 0.6 15 815 24.5 18.5 6.2 50 880 51.2 26.7 4.5 45 515 25.0 18.6 4.4 12 hr. 885 40.6 52.8 7.8 15 880 57.9 52 8 5.1 50 1085 44.1 57.9 6.2 45 95 5.1 2.6 0.5 15 hr. 250 8.5 7.5 1.2 15 745 29.8 24.8 5.0 50 540 12.1 9.7 2.4 45 515 11.5 9.5 2.5 14 hr. 870 51.2 24.8 6.5 15 450 19.7 16.2 5.6 50 540 25.4 19.1 4.5 45 610 26.7 22.1 4.5 15 hr. 800 57.8 51.8 6.0 15 415 19.2 16.5 2.7 50 1020 49.2 40.1 9.1 45 740 52.7 28.0 4.7 16 hr. 200 9.5 8.1 1.2 Table 50. (Continued) Time Volume Dry matter Organic matter Ash (min.) (ml.) (g.) (g.) (g.) 15 460 21.5 18.5 2.8 50 845 57.1 51.9 5.2 45 790 54.5 29.9 4.4 17 hr. 220 9.5 7.8 1.5 15 700 .52.5 28.8 5.7 50 220 11.2 9.7 1.5 45 955 47.8 40.9 7.0 18 hr. 660 26.6 22.0 4.6 15 650 22.6 18.9 5.7 50 1110 40.4 55.6 6.8 , 45 1265 45.4 55.9 7.5 g 19 hr. 420 11.9 9.4 2.5 15 575 12.6 10.8 1.8 50 550 10.2 8.5 2.0 45 460 14.7 12.0 2.7 20 hr. 950 52.5 26.1 6.2 15 540 12.2 9.9 2.5 50 780 55.6 50.7 4.8 45 910 58.9 55.2 5.6 21 hr 685 21.8 16.6 5.2 15 720 18.1 14.5 5.6 50 515 8.1 6.8 1.4 45 415 11.5 9.6 1.9 22 hr. 675 18.4 15.7 2.8 15 1070 51.6 24.4 7.2 50 600 16.1 12.1 4.0 45 510 9.2 7.5 1.9 25 hr. 620 17.8 14.7 5.1 15 405 12.9 10.2 2.7 50 280 11.0 9.6 1.4 45 580 25.8 20.8 5.0 24 hr. 720 28.6 25.5 5.5 522 659 m1. (range, 75-1665 ml.) for R52, 758 m1. (range, 0-1700 ml.) for R41 and 705 m1. (range, 95-1550 ml.) for R42. Com- paratively good agreement was Obtained between the mean vol- umes of ingesta collected for a given ration. More frequent feeding decreased the mean volume in each case and tended to confine the amplitude of the sampling period variations within a somewhat narrower range (see Figures 19 through 25). Because the fluctuating variations make it difficult to compare the differences in passage of ingesta between rations, regressions of passage on time were computed to give values which would depict the passage curve in its entirety. Rate of passage, calculated from the accumulated data and summarized for each ration in Table 51, represents quantitative passage per unit of time. Rate of increase or decline, computed from the raw data and summarized for each ration in Table 52, is Table 51. Effect of ration and feeding on rate of passage of ingesta from the duodenum R11 R21 R22 R51 R52 R41 R42 Volumea 555 852 749 669 648 705 699 Dry matterb 19.7 28.7 27.3 28.7 25.0 24.2 27.4 Organic matterb 16.6 24.6 25.1 24.1 21.1 19.7 22.7 Ashb 5.1 4.0 4.2 4.5 5.9 4.6 4.7 8Expressed in ml. per 15 minutes bExpressed in g. per 15 minutes 525 Table 52. Effect of ration and feeding on rate of decline of ingesta from the duodenum R11 R21 R22 R51 R52 R41 R42 Volumea -4.45 5.25 -2.54 -4.95 -1.01 —4.57 -5.51 Dry matterb -1.54 0.52 —1.54 —2.62 -1.os -1.55 -1.46 Organic b matter —1.12 0.42 -1.21 -z.54 -O.96 -1.17 -1.22 Ashb —0.22 0.10 -0.15 -0.58 -0.11 —0.58 -o.24 aExpressed in ml. per 15 minutes bExpressed in g. per 15 minutes indicative of the general trend of the data and its rate of occurrence. The passage of total ingesta for the high corn- 1ow hay ration was about 20 percent more rapid than for the high-hay or all-hay rations. Passage for these latter rations was, in turn, approximately 20 percent more rapid than for R11. The differences in rate of passage between R5 and R4 were minor (6 percent). Rates of passage were lowered in every case by increasing the frequency of feeding. Excluding the value for 321 which indicates a general increase in passage, values for the remaining rations show a .decline in passage of total ingesta with time. The values for rations fed once daily were comparatively similar whereas the values for rations fed more frequently were less congruous. The rates of decline, however, were consistently reduced by more frequent feeding. The percentage of solids in tne ingesta (Appendix Tables 10 through 16) was usually elevated in connection with high flow volumes, but this was not always the case and the rela- tionsnip between flow volume and percent solids was by no means a direct one. The solids content pattern appeared to follow a course more or less independent of flow and to be influenced by factors other than volume itself. With R11 and R21 the initial dry matter content was about 2.8 percent. This increased to a maximum level of 4.8 percent at approxi- mately 10 hours and thereafter declined to its initial level at 24 hours. More frequent feeding (R22) resulted in the dry matter starting at a near maximum of about 4.2 percent. There- after the dry matter gradually declined to a level of 5.8 per- cent. The dry matter content of the ingesta with R51 showed two distinct peaks, one at 1 hour (6.8 percent) and the other at 8 hours (7.5 percent) after feeding. Similarly Spaced, but lower peaks (5.5 and 6.0 percent, respectively) were observed as a result of feeding this ration (R52) twice-a—day. The dry matter percentage pattern of the ingesta with R41 was also characterized by two peaks. The initial peak (5.4 percent) occurred at 1 hour while the second (5.5 percent) was delayed until between 15 and 14 hours post cenam. Twice-a-day feeding eliminated these peaks to a large extent and resulted in a general decline of about 1 percent over the entire 24-hour period. The mean dry matter content of the ingesta was 5.4% for R11, 5.2% for R21, 5.6% for R22, 4.1% for R51, 5.7% for R52, 5.5% for R41 and 5.8% for R42. The concentration of organic matter was a reflection of the dry matter content and followed a similar pattern of change. The mean percentage of organic matter was 2.8% for R11, 2.7% for R21, 5.1% for R22, 5.4% for R51, 5.1% for R52, 2.7% for R41 and 5.2% for R42. The ash content, although variable between sampling periods (particularly with R4), tended to follow a more constant pat- tern than that for dry matter or organic matter. An occasional sample of ingesta was considerably higher in ash and lower in. organic matter than usual due to the passage of blobs of sand down the tract. The mean asn content of the ingesta was 0.6% for R11, 0.5% for R21, 0.5% for R22, 0.7% for R51, 0.5% for R52, 0.6wafor R41 and 0.7% for R42. The passage of dry matter, organic matter and ash (Tables 24 through 50) followed patterns very similar to those of total ingesta (Figures 19 through 25). High flow volumes were accom- panied by an elevated passage of solids. The range and mean passage of dry matter from the duodenum per 15 minutes was 19 g. (0.4-67 g.) for R11, 27 g. (0-84 g.) for R21, 50 g. (2-79 g.) for R22, 29 g. (4-116 g.) for R51, 25 g. (5-75 g.) for R52, 25 g. (0-82 g.) for R41 and 27 g. (5-66 g.) for R42. Corresponding values for the passage of organic matter were 16 g. (0.5-59 g.) for R11, 25 g. (0-72 g.) for R21, 25 g. (2-68 g.) for 322, 25 g. (5-105 g.) for R51, 21 g. (2-55 g.) 526 for 352, 21 g. (0-55 g.) for R41 and 25 g. (5—57 g.) for R42 while the range and mean passage of ash was 5.2 g. (0.1-8 g.), 5.9 g. (0-12 g.), 4.4 g. (0.5-11 g.), 4.6 g. (0.7-11 g.), 4.0 g. (0.5410 g.), 4.8 g. (0~16 g.) and 4.6 g. (0.5-10 g.) for the same rations, respectively. If the frequency of feeding is disregarded the differences in mean passage between collections for a given ration were equally as great as those between rations, excluding R11. Increased frequency of feed- ing was inconsistent with reapect to its effect on mean pas— sage but it did consistently narrow the range of solids output with each ration. The passage of dry matter from the duodenum (Table 51) was considerably more rapid (25-29%) when hay was part or all of the ration than when only corn was fed. On the other hand, relatively minor differences (4-72) in rate of dry matter pas— sage were noted between the rations containing hay. With these rations passage was most rapid with R2, less rapid with R5 and least rapid with R4. More frequent feeding of the mixed rations resulted in a decreased rate of dry matter pas— sage. The rate of passage of dry matter was increased by feeding only hay twice daily. Similar, but slightly greater differences between rations were observed for organic matter . passage. The response of organic matter passage to more fre- quent feeding was the same as that noted for dry matter. With the exception of R11, the results for the rate of 327 passage of ash were reversed from those for dry matter and organic matter. There appeared to be a relationship between ash intake and the rate of passage of ash although the rela- tionship was not a direct one. Inorganic materials passed least rapidly with R1 and most rapidly with R4 and, in gen- eral, increased with increasing ash intake. Twice-a-day feeding increased ash passage with R2 and R4 but decreased the rate of passage with R3. The differences between rations with respect to the effect of more frequent feeding are of interest because the supplemental inorganic material (15-59% of the total asn intake) was given only once daily at the O-hour feeding with all rations. The general trends of passage and their corresponding rates are presented in Table 52. All rations, with the excep- tion of R21, resulted in a decline in passage with time. R21 resulted in an increase. This collection appears to be an oddity, however, for it was the only collection out of 14 different trials (seven are reported here) which exhibited a general increase in passage. The rate of decline (-4.4 to -4.9 ml./l5 minutes) of total ingesta for the different rations fed once daily were remarkably similar. This similarity did not exist when the rations were fed more frequently. On the other hand, the rates of decline were reduced in each case by this procedure. Results for the rates of decline of dry matter were 528 somewhat more erratic between rations fed once daily than with total ingesta. There was much closer agreement, however, be- tween the rates for each ration. This was particularly true when the rations were fed twice daily. With the exception of the values for Rzl and R51, the rates of decline only varied over a range of -l.l to -l.6 g. per 15 minutes. Again, as for total ingesta, the rates of decline were reduced by feed- ing the ration more frequently. Trends similar to those for dry matter were obtained for organic matter with the exception of R42. With this ration the rate of decline was increased slightly as a result of more frequent feeding rather than being reduced. The rates of decline of ash were markedly more rapid when the rations were fed once daily than when fed more frequently. In this respect ash passage more nearly resembled that of total ingesta than that of dry matter or organic mat- ter. On the other hand, values for the decline of ash were less erratic between rations fed twice daily than were those for tOtal ingesta decline. The similarities between rates of decline for the various rations and frequencies of feeding were rather surprising in view of the relatively wide differ- ences in intake of organic matter and of ash between rations. Effect of eating and rumination ongpassage In an attempt to determine the effect of eating on the passage of ingesta from the duodenum the following procedure 529 was employed. The amount of time Spent eating was computed as a fraction of the total time (15 minutes) for each respec- tive period in whicn eating occurred. Each value was in turn multiplied by the total quantity of ingesta passed during that period. The resultant products represent the passage of in- gesta during eating for each particular period. Total passage of ingesta during eating was derived by summation of the indi- vidual period products. Passage per minute was determined by dividing the total passage during eating by the total time spent eating. Values for passage during rumination and dur- ing rest (not eating or ruminating) were calculated similarly. The final values for volume, dry matter, organic matter and ash, computed for comparative purposes on the basis of quan— tity passed per 15 minutes, are presented in Table 53. The data indicate that passage, irrespective of ration, usually was accelerated during the period of time the animal was eating although this was not always the case. Less in— gesta was passed during eating with R21 and ESL, but only with Roz was passage markedly lower than the mean passage. These values may be more apparent than real, however, due (1) to the arbitrary boundaries established for the sampling periods and (a) to the means by which the values were computed. For example, Figure 20 indicates the initial passage with R21 was not particularly low during eating with respect to the mean passage of ingesta, yet it was low relative to the amount of 550 Table 55. Effect of eating and rumination on passage of ingesta from the duodenum R11 R21 R22 R51 R52 R41 R42 Volume Lmlt/l5 min.) Eating 808 792 1254 1052 449 1108 769 Ruminating -- 992 54s 67? 674 715 591 Not eating or _ ruminating 555 815 815 669 664 722 727 Dry matter figL/lS min.l Eating 26 21 47 48 18 55 50 Ruminating —- 50 18 29 26 22 21 Not eating or ruminating 19 27 51 29 25 25 28 Organic matter Lg,[15 min.) Eating 21 17 41 47 15 45 25 Ruminating -- 25 16 24 22 18 18 Not eating or ruminating 16 25 26 24 21 2O 24 Ash LgL/15 min.1 Eating 4.4 5.5 6.6 6.8 2.7 9.0 4.8 Ruminating -- 4.4 2.9 4.5 4.1 4.6 5.6 Not eating or ruminating 5.1 5.8 4.6 4.5 4.0 4.6 4.8 ingesta passed in the later stages of the collection. Again, passage of ingesta during the hour immediately following eating was considerably less than it was during eating. With R52 the time Spent eating occurred during periods of low flow but in each case these periods were followed by periods of acceler- ated flow. Thus, it would appear the accelerated flow was a 531 result of eating. When the high-hay rations were fed only once daily passage was markedly higher during eating than wnen these rations were fed more frequently. The reverse of 'this occurred with the high-grain, low-hay ration. Relation— ships similar to those for the effect of eating on total pas- sage were obtained for dry matter, organic matter and ash passage. Rumination was abolished by feeding Rll. The effect of . rumination on the passage of total ingesta for the remaining rations was the reverse of the effect of eating on passage. Passage with R22, R51, R41 and R42 was less than the mean during rumination whereas passage with R21 and R52 was greater than the mean. Relationships between rations for the passage of solids during rumination were similar to those for total ingesta, with one notable exception. Frequency of feeding exerted no consistent influence on the passage of total in- gesta. The passage of solids during rumination, however, was lowered in every instance by more frequent feeding. Unusually close agreement between trials for a given ration was obtained for the passage of total ingesta during periods when the animal was neither eating nor ruminating. Passage pg; g2 during this time was affected little by the frequency of feeding but it is of interest that passage for R11, R21, R51 and R41 was less than each respective mean whereas passage for R22, R52 and R42 was greater than each 552 respective mean. This was true, however, only for total in— gesta. Passage of the solids was approximately the same with each ration as its respective mean. Effect of ration and frequency of feeding on the composition of ingesta passed from the duodenum Appendix Tables l7 through 25 show the volume and compo- sition of the ingesta passed from the duodenum during hourly intervals of a digestion cycle (24 hours) for each ration. Quantitative data was calculated from these tables and are summarized for each ration and frequency of feeding in Tables 54 through 40. The methods of computation are described in the results of the preliminary eXperiment. Passage pattern fluctuations again were eliminated to a large extent by com— puting the data on an hourly basis and passage trends were not appreciably altered by the procedure. The mean volume of in- gesta passed from the duodenum per hour was 2282 m1. (range, 870-5090 ml.) for R11, 5528 ml. (range, 1860-5275 ml.) for R21, 5181 m1. (range, 2125-5850 ml.) for R22, 2740 m1. (range, 1450-5520 ml.) for R51, 2655 m1. (range, 1505-5975 ml.) for R52, 2950 m1. (range, 1745—4590 ml.) for R41 and 2818 ml. (range, 1985-5870 ml.) for R42. With the exception of R21 and R52, maximum passage of the ingesta occurred within the first two hours of each collection. Minimum passage was ob- served between 4 and 8 hours with the high-grain rations whereas it occurred between 18 and 24 hours with the high-hay 555 Table 54. Effect of R11 on the quantity of ingesta components passed from the duodenum Dry Organic Protein Ether Crude N-free Time Volume matter matter (Nx6.25) extract fiber extract Ash (an) (ml.) (g.) (g-) (g-) (g.) (g.) (g.) (g.) l 2940 90.0 70.5 29.9 11.2 4.2 24.9 19.7 2 5090 157.8 122.1 52.8 19.5 6.0 44.0 55.6 5 2500 78.8 61.9 25.7 9.7 2.5 24.0 16.8 4 2550 75.4 57.5 24.7 9.5 1.7 21.6 16.2 5 2820 79.0 61.5 27.2 10.2 2.1 22.0 17.4 6 2845 89.6 71.6 50.6 11.5 5.0 26.4 18.0 7 2240 77.5 62.8 26.5 10.1 2.6 25.7 14.7 8 870 51.8 26.4 10.5 5.9 1.4 10.8 5.5 9 1600 59.5 49.7 18.4 7.0 2.7 21.6 9.8 10 5515 151.5 111.2 40.4 14.7 6.9 49.1 20.0 11 5105 125.9 105.5 57.7 15.9 6.7 47.2 18.4 12 1900 65.0 55.7 22.5 7.8 2.5 21.0 11.5 15 2515 82.5 68.6 28.0 10.0 5.5 27.2 15.9 14 2460 85.6 70.7 29.5 10.2 4.0 27.0 14.9 15 2875 85.1 69.5 51.5 10.9 2.7 24.5 15.8 16 1825 61.5 50.5 21.6 7.1 5.0 18.8 11.0 17 1600 49.9 40.7 17.9 5.9 2.0 14.9 9.2 18 1470 46.2 56.9 17.7 5.1 1.4 12.6 9.2 19 1520 50.6 41.2 18.5 5.5 2.4 15.5 9.4 20 1790 60.5 49.2 21.5 6.5 2.9 18.4 11.5 21 1855 61.7 50.4 21.5 6.5 5.0 19.4 11.5 22 2080 67.4 54.2 24.4 7.5 2.8 19.6 15.2 25 1550 45.9 55.5 15.4 4.2 2.2 15.7 8.4 24 1715 56.4 45.2 19.8 5.8 2.7 17.0 11.2 rations. The range and mean passage of dry matter from the duodenum per hour was 75 g. (52-158 g.) 205 g.) for R21, 129 g. (84-246 g.) for for R11, 119 g. (64- R22, 115 g. (46-268 g.) for R51, 96 g. (59-160 g.) for R52, 106 g. (62-225 g.) for R41 and 108 g. (59-148 g.) for R42. Corresponding values Table 55. 554 Effect of R21 on the quantity of ingesta components passed from the duodenum Dry Organic Protein Ether Crude N-free Time Volume matter matter (Nx6.25) extract fiber extract Ash (nr.) (ml.) (g.) (g.) (g-) (g-) (g-) (g.) (g.) 1 5240 87.2 64.2 22.4 7.6 8.8 25.4 25.0 2 2420 66.1 50.5 16.7 5.6 6.1 22.0 15.6 5 2290 67.8 49.4 17.2 5.6 7.2 19.4 18.4 4 2160 64.2 46.9 16.5 4.9 8.5 16.9 17.2 5 4460 147.6 115.9 56.4 10.5 15.6 51.5 55.7 6 5515 128.7 101.4 51.0 9.5 15.7 47.2 27.5 7 2970 119.4 95.8 28.0 9.7 15.7 44.5 25.5 8 1860 75.0 60.6 17.9 6.1 8.8 27.8 14.4 9 5085 141.9 117.1 52.4 11.6 17.6 55.5 24.8 10 4560 205.8 171.5 46.5 17.7 25.0 82.0 52.6 11 5160 140.6 117.5 55.4 11.2 17.1 55.5 25.5 12 2570 118.5 98.9 27.1 9.6 14.0 48.2 19.5 15 5475 154.5 108.9 54.9 11.4 15.9 48.6 25.6 14 2970 108.4 86.4 29.4 9.8 9.8 57.4 22.0 15 5555 126.8 101.5 55.1 12.1 12.2 42.0 25.5 16 2515 100.1 81.7 26.1 8.5 10.5 56.6 18.4 17 4705 205.1 168.5 49.6 16.5 21.8 80.4 56.6 18 5145 117.5 95.2 29.7 9.7 11.8 42.0 24.1 19 2750 85.9 62.5 25.6 7.8 6.2 24.7 21.5 20 5080 166.6 128.6 45.2 14.5 17.6 51.1 58.1 21 5520 115.0 87.1 29.2 9.9 11.4 55.4 25.9 22 5275 155.6 115.9 42.0 12.9 14.4 46.5 59.7 25 4555 111.5 80.8 29.8 8.5 9.8 52.6 50.7 24 2495 76.9 57.9 20.2 6.4 8.9 22.5 19.0 for the passage of organic matter and ash were as follows: organic matter, 61 g. (as-122 g.) for 311, 94 g. (47-169 g.) for R21, 105 g. (70-204 g.) for R22, 95 g. (55—228 g.) for 351, 76 g. (29-127 g.) for 352, 81 g. (44—180 g.) for 341, 82 g. (42-116 g.) for 342; ash, 14 g. (s-ss g.) for 311, 25 g. 555 Cable 56. Effect of R22 on the quantity of ingesta components passed from the duodenum Dry Organic Protein Ether Crude N-free Dime Volume matter matter (Nx6.25) extract fiber extract Ash (hr.) (ml.) (8.) (g.) (g.) (g.) (g. (g.) (g) 1 5850 246.5 204.1 77.5 18.9 28.8 78.8 42.2 2 4170 195.9 162.7 52.5 14.9 2 .9 75.2 51.2 5 5170 141.7 117.9 59.1 11.5 15.9 55.6 25.8 4 2125 95.0 78.8 27.9 8.6 9.7 52.5 16.2 5 4080 199.5 168.8 55.4 16.1 25.6 75.5 50.7 6 4290 184.0 157.7 55.5 16.6 19.0 46.7 46.5 7 2800 112.6 88.2 54.5 9.6 9.5 54.8 24.5 8 2180 84.4 69.5 26.1 7.6 7.1 28.5 14.9 9 2605 106.8 86.0 52.4 9.0 9.0 55.6 20.8 10 2770 112.2 87.8 55.4 10.5 9.2 52.8 24.4 11 2865 127.8 107.5 59.6 10.9 11.8 '44.9 20.5 12 5720 179.7 142.6 51.4 14.8 18.2 58.1 57.1 15 _2820 112.0 92.8 56.4 9.4 8.6 58.2 19.2 14 2810 118.6 98.7 56.5 10.0 10.4 41.7 19.9 15 2295 87.9 71.9 (28.7 7.4 6.0 29.8 16.0 16 2265 86.5 70.7 27.6 6.8 7.0 29.5 15.6 17 5980 158.5 110.4 47.6 11.5 9.8 41.5 28.1 18 2715 99.9 80.9 52.0 8.1 7.7 55.1 19.0 19 5455 120.2 96.1 40.4 9.6 8.6 57.4 24.2 20 5050 110.0 88.4 56.2 8.6 8.6 54.9 21.6 21 2620 98.0 79.2 51.1 7.8 8.5 51.7 18.8 22 5205 118.9 95.5 57.1 9.4 10.0 58.8 25.7 25 5660 129.6 105.1‘ 42.0 11.5 11.1 58.6 26.5 24 2950 107.0 85.0 55.5 9.7 10.4 51.4 21.9 [14-40 g.) for R21, 24 g. (15—46 g.) for R22, 22 g. (ll-41 g.) for R51, 21 g. (10-55 g.) for R52, 25 g. (15-47 g.) for R41, 26 g. (17-57 g.) for R42. The periods, in which minimum and naximum passage of dry matter, organic matter and ash occurred, coincided for the most part with those for total ingesta. The 356 Table 57. Effect of R51 on the quantity of ingesta components passed from the duodenum Dry Organic Protein Ether Crude N-free Time Volume matter matter (Nx6.25) extract fiber extract Ash (hr.) (ml.) (g.) (g-) (g-) (g-) (g-) (g.) (g) 1 5520 268.7 227.6 61.6 15.5 41.7 108.6 41.1 2 5655 179.5 150.2 57.5 9.8 26.6 76.4 29.5 5 1845' 58.7 44.9 15.5 5.5 6 2 19.6 15.8 4 5960 125.2 95.1 54.2 8.1 15.1 55.5 50.1 5 5580 115.9 88.5 51.2 6.9 15 5 54.8 27.5 6 2550 96.9 76.4 19.0 6.0 15.1 56.5 20.5 7 5105 125.9 98.1 25.4 8.1 19.7 46.8 25.7 8 5845 208.0 176.4 46.0 15.8 59.5 77.1 51.6 9 2755 164.7 159.0 44.1 11.7 27.5 55.6 25.7 10 1955 87.4 71.0 19.2 7.0 12.6 52.2 16.4 11 5250 145.5 115.0 57.5 11.4 18.8 47.2 28.5 12 2155 92.5 74.9 25.6 7.4 12.5 29.4 17.5 15 2855 119.1 95.8 58.1 9.1 16.1 52.5 25.5 14 5440 155.8 107.8 41.7 10.9 17.9 57.2 26.0 15 2095 86.5 69.6 26.8 6.4 11.8 25.1 16.9 16 2410 86.8 68.4 25.9 6.5 11.5 24.6 18.4 17 2170 67.7 55.5 22.1 5.C) ’743 18.5 14.4 18 1500 54.5 45.6 16.5 5.9 7.5 16.0 10.8 19 2850 120.8 96.4 54.5 8.4 18.6 54.8 24.5 20 2570 95.6 75.9 28.7 7.2 15.8 26.1 19.7 21 2560 111.4 91.4 26.6 6.9 17.2 40.6 20.0 22 2550 100.5 80.1 28.4 7.5 14.7 29.6 20.4 25 1450 45.8 55.1 15.8 5.7 5.6 11.9 10.7 24 1850 79.9 64.8 20.4 6.0 14.0 24.5 15.1 . rates of passage (Table 41) and increase or decline (Table 42) of dry matter, organic matter and ash followed same trends as they did when computed from the and consequently will not be discussed further essentially the lS—minute data at this point. Passage of the organic components (Figure 27) from the Table 58. 557 Effect of R52 on the quantity of ingesta components passed from the duodenum Dry Organic Protein Ether Crude N-free Time Volume matter matter (Nx6.25) extract fiber extract Ash (hr) (ml.) (g-) (g-) (g.) (g.) (g-) (g.) (g-) 1 5850 140.9 108.5 55.2 9.9 19.5 45.8 52.5 2 2715 108.6 85.5 25.7 7.1 16.0 58.7 25.1 5 2250 64.6 47.2 16.7 4.7 7.5 18.5 17.4 4 2490 90.4 70.5 21.5 6.5 15.2 29.1 20.1 5 2950 116.6 91.5 28.7 8.7 18.9 55.0 25.1 6 2560 84.5 64.0 22.1 6.4 11.5 24.1 20.5 7 2985 119.7 95.0 50.9 8.5 18.1 57.6 24.7 8 5050 145.7 117.5 55.4 9.7 22.8 49.4 26.5 9 1690 79.4 64.8 19.5 5.5 11.5 28.6 14.7 10 5545 146.4 116.8 59.6 10.6 16.8 49.8 29.6 11 2650 104.7 84.5 29.1 7.5 12.2 55.4 20.4 12 2650 97.6 77.9 28.1 7.5 11.0 51.5 19.7 15 2685 88.9 68.6 27.4 6.4 8.5 26.5 20.2 14 2060 65.7 48.7 20.5 4.8 5.5 18.1 15.0 15 2555 86.2 68.1 25.2 5.9 9.0 28.0 18.1 16 5975 141.6 110 6 40.6 10.1 15.5 44.5 50.9 17 1990 58.5 44.4 17.2 4.1 4.7 18.5 14.1 18 1505 58.7 29.0 11.8 2.8 5.2 11.1 9.7 19 2570 72.8 55.4 21.5 5.5 7.5 21.4 17.4 20 2985 110.2 85.7 50 5 7.6 12.5 55.2 24.4 21 2565 105.9 81.5 25.7 6.7 12.5 56.5 22.6 22 2150 60.5 45.5 17.4 4.5 6.0 17.6 15.0 25 1605 47.7 55.8 15.9 5.4 5.0 15.6 11.9 24 5955 159.8 126.7 57.7 9.7 19.4 59.9 55.1 upper gut for a given ration and frequency of feeding in gen- eral followed patterns with time similar to those followed by total ingesta (Figures 19 through 25). tion, both within and between trials, was observed for the output of the various components per hour. Considerable varia- lore frequent 558 Table 59. Effect of R41 on the quantity of ingesta components passed from the duodenum Dry Organic Protein Ether Crude N-free Time Volume matter matter (Nx6.25) extract fiber extract Ash (hr.) (ml.) (g-) (g-) (g-) (g.) (g.) (g.) (g) 1 4440 225.1 180.0 70.4 11.5 56.5 41.6 45.1 2 4590 216.2 169.1 48.8 10.8 49.4 60.1 47.0 5 5200 92.2 65.6 27.2 5.9 10.2 22.2 26.6 4 4490 151.1 95.4 55.7 7.5 17.5 54.7 55.7 5 2610 65.5 44.9 18.2 5.5 6.5 16.7 20.6 6 5695 82.8 54.4 25.5 4.1 6.7 20.2 28.4 7 5400 78.2 51.8 21.8 5.6 6.7 19.6 26.4 ' 8 5580 88.6 62.6 25.4 4.0 11.5 25.8 25.9 9 2815 85.7 62.7 25.5 4.2 12.5 22.6 25.2 10 2750 89.1 66.2 25.9 4.6 12.8 25.0 22.9 11 2120 82.0 65.7 21.5 4.5 14.1 25.8 18.5 12 2505 101.0 80.4 27.2 5.9 18.5 28.7 20.6 15 2400 125.5 102.6 51.8 7.1 27.0 56.6 22.7 14 5045 159.0 129.0 42.4 9.7 51.9 44.8 50.0 15 4040 164.8 128.6 50.8 11.4 22.0 44.4 56.2 16 2180 92.2 75.0 28.0 6.1 15.5 25.5 19.2 17 2155 88.0 69.8 27.6 6.0 12.8 25.4 18.2 18 1745 64.2 49.7 21.0 4.6 7.4 16.7 14.5 19 2260 95.6 75.9 27.7 6.2 15.5 24.6 19.7 20 2685 98.5 75.6 50.8 7-0 12.7 25.0 22.7 21 2655 97.8 76.2 28.7 6.8 15.2 25.4 21.6 22 5295 97.9 72.2 51.5 7.0 9.6 24.1 25.6 25 2410 78.8 59.8 22.0 5.0 11.4 21.4 19.0 24 2220 61.5 44.2 18.6 4.5 6.2 15.0 17.5 feeding tended to reduce tne within trial variations. , Protein output from the duodenum is shown in Tables 55 through 40. The mean and range of protein passed per hour was 26 g. (lo-55 g.) for R11, 50 g. (17-50 g.) for R21, 40 g. (26-78 g.) for R22, 50 g. (14-62 g.) for R51, 26 g. (12-41 g.) 559 Table 40. Effect of R42 on the quantity of ingesta components passed from the duodenum Dry Organic Protein Ether Crude N-free Time Volume matter matter (Nx6.25) extract fiber extract Ash (hr) (ml-) (g.) (go) (g.) (g.) (g.) (g.) (g.) 1 5155 148.0 116.1 54.0 7.9 15.9 60.4 51.8 2 5870 146.5 109.5 56.5 8.2 26.0 58.9 56.7 5 5585 125.5 95.2 50.4 7.2 25.7 55.8 50.5 4 2890 87.0 62.8 22.1 4.7 15.2 22.7 24.2 5 5225 106.8 79.7 26.0 6.1 19.6 27.9 27.1 6 5170 112.9 85.6 25.9 6.5 22.6 50.6 27.5 7 5020 107.8 80.8 25.2 6.2 20.0 29.4 27.0 8 2815 112.6 85.6 24.9 6.0 25.7 50.8 27.0 9 5225 155.8 105.2 29.4 7.2 28.8 59.8 50.6 10 5450 155.9 102.2 51.5 7.5 24.9 58.5 55.7 11 5080 150.5 99.4 29.8 7.0 25.9 56.6 50.9 12 5095 125.0 96.2 51.8 6.9 22.0 55.4 28.8 15 2290 95.9 72.4 25.7 5.5 16.5 26.9 21.5 14 2270 88.8 68.5 24.5 5.1 15.8 25.1 20.2 15 2580 105.9 5.1 29.9 6.4_ 17.6 29.2 22.8 16 2575 108.1 85.5 29.9 6.2 18.5 51.1 22.6 17 2515 100.7 79.9 29.1 6.5 16.8 27 6 20.8 18 2555 115.6 91.4 51.2 6.6 22.5 51.5 24.2 19 5445 116.8 87.5 55.7 6.6 14.2 51.0 29.5 20 2095 70.2 55.1 20.8 4.1 9.4 18.8 17.0 21 2715 109.4 85.1 27.9 5.6 22.1 29.5 24.4 22 2125 59.1 42.5 17.5 5.2 6.5 15.5 16.7 25- 2600 80.9 60.5 22.5 4.5 11.4 21.8 20.6 24 1985 74.8 58.2 19.2 4.0 14.9 20.0 16.6 for R52, 50 g. (18-71 g.) for R41 and 27 g. (18-56 g.) for R42. Considerable variation in hourly output occurred within a given trial. Obvious differences in passage between rations also were observed but these differences were not as great as might have been expected in view of the different levels of 340 Figure 27. Effect of ration and frequency of feeding on the output of organic matter and ash from the upper gut (organic matter,.————. ; ash, A———-A) I») 00!.“ m .341 RH :00. I40. I40. A .10!- 3 EIOO). 3 no). to). l l L L L L 1 J; 1 l I 2 4 4 0 I0 I2 I4 I4 I. 20 22 24 TIMHM) R2! R22 I00. "or. I40. I40. I20. :I20. I00. iIOO. 00. 3 .0. .0. .0h 40. 40L tor-W 20). L l I l l l l l l 1 L4 1 A l l l 1 l I 1 l J 2 4 0 0 I) I2 I4 I4 3 20 22 24 2 4 I I0 I2 I4 B I. 20 22 24 TIII. In.) Th. (hr.) RBI R32 I00. I00). I00. I00. I40. I40. “or into. '”b 1.00» N. 3 00,. 00.. 00.. 40. 40). '° “wa A 1 l I 1 l 1 l l l 1 J L l 1 l L 1 l l l l J 2 4 4 0 I0 I2 I4 I. I. 20 22 24 2 4 I I0 I! I4 I4 I. 20 22 24 TIM. (hr.) TIC. IN.) R4I R42 l00. I00. I40. I80. I40. I40). no. alto} I00 I00. * 3 .0» o ”3 .Op ”b 40. 40.. 80 20pm 1 1 A L J 1 n 1 4 L 4 J 1 L 1 1 1 1 L l 1 L 4 2 4 I 0 I0 I2 I4 I4 I. 20 22 24 2 4 0 I0 I2 I4 IS I. 20 22 24 TIM. (hi) I’m. (hr.) 542 9:0: pom .m 230: mom .Ha CH Ummmohmxmn ca commmnquw on.mm mm.wu on.om wn.Hn 6H.nn mm.mn on.na n£m4 00.0m mm.bN ww.on hm.nn Om.mn om.©¢ om.nm onmhpxm omhhlz nn.ma ¢M.ma nm.aa HH.©H H©.oa 05.na 0H.n samba“ mcsho mo.© No.0 56.0 00.6 ma.oa no.0a Nb.m onmhpxm Aoflum Ob.bm N©.mm om.nm an.mm b¢.bn em.afi mo.mm QGHmponm ma.nm 28.22 22.42 om.mm 28.28 ou.»oa nm.om 2205523 oaswwgo vb.moa b©.ooa om.¢m 0¢.OHH nm.oma N©.bNH mx.¢b thppma Aha OH.mbom 06.6mbm om.¢onu om.o¢©m om.bmmu om.o¢nn om.HmHm wmadao> Nwm me Nam Ham mum Hum Ham ascocoso on» song mpcm:omaoo mummwca mo mwmmmmm mo mpmm map so wcdumom dam coapmn no poommm .Hw magma 545 5562 56m .w 5H commm5mxmn 5365 56m .Ha ha commmnnxmm 55.6- 45.6- 55.6- 46.6- 64.6- 66.6 56.6- 5554 65.6- 56.6- 55.6- 56.5- 55.5- 22.6 56.6- 55655556 6655-2 64.6- 55.6- 42.6- 56.6- 66.6- 56.6 26.6- 555655 62556 55.6- 66.6- 65.6- 65.6- 45.6- 55.6 55.6- 55625556 56555 65.6- 66.6- 65.6- 66.6- 66.6- 66.6 56.6- 55565655 m6.5- 66.5- 56.6- 42.6- 66.5- 46.5 66.5- 5565525 6552556 65.5- 66.5- 25.5- 56.5- 66.n- 24.5 55.5- 5565565 555 65.5- 45.5- 66.5- 56.5- 65.5- 55.6 55.5- «635565 542 545 mam 56m 552 Ham Ham 35566656 625 3655 mpcmaomaoo mummwca mo oaaaomo 96 6565 6:5 56 wcacmmm and 565565 56 uomumm .mw magma 544 protein intake. More frequent feeding reduced the mean pas- sage and within—trial variation in output with the high-hay rations. With Re the reverse occurred. The rate of passage of protein (Table 41) was substan- tially more rapid with the high-grain, low—hay ration than with any of the other rations. Rates of passage for the high-hay rations were similar. Protein passage was least rapid with R11 but it was not markedly so compared to passage with R5 and R4. The rate of protein passage was reduced by feeding the high-hay rations twice daily whereas it was in- creased oy feeding Ra according to the same procedure. Protein output from the duodenum with time declined with all rations except Rzl. With this ration there was an increase in passage, particularly during the later stages of the trial. Similar rates of decline were obtained for R11, R22, R51 and R41. In each case these rates were a reflection of rapid pas- sage during the first 2 hours of the trials. More frequent feeding eliminated to some extent the rapid initial passage and consequently reduced the rate of decline. Values for the output of ether extractive material from the upper gut are found in Tables 54 through 40. The mean and range of ether extract passed per hour was 8.9 g. (5.9- 19.5 g.) for Rll, 9.9 g. (4.9—17.7 g.) for R21, 10.8 g. (a.s- 18.9 g.) for sz, 7.9 g. (5.5-15.5 g.) for R31, 6.8 g. (2.8- lO.6 g.) for R52, 6.5 g. (5.5-11.5 g.) for R41 and 6.0 g. 545 (5.z-b.z g.) for R42. The patterns of passage for this frac— tion were very similar to those for protein for each reSpec- tive ratiOn. Within-trial variations in hourly output again were evident as were the differences in output between rations. Excluding fill, the passage of ether extract appeared to be related at least in part to the level of ether extract intake. The relationsnip was not direct, however, for compared with intake prOportionately more ether extract was passed with R2 than was passed with R5 or R4. Although Rll contained the highest level of ether extract, it resulted in the lowest quantity of ether extract passed in the ingesta. Increasing the frequency of feeding seemed to reduce the within—trial variations in output per hour but had little influence on the mean passage of ether extract for a given ration. The rates of passage of the ewmr extractive materials from the duodenum are presented in Table 41. Passage with R2 was approximately 20, 50 and 40 percent more rapid than with R1, R5 and R4, respectively. Excluding R1, the rate of pas- sage of ether extract appeared to be almost directly related to its intake. Twice-a—day feeding did not appreciably alter the rate of ether extract passage. Data presented in Table 42 indicate that the quantity of ether extract passed from the duodenum prOgressively declined over a z4-hour period with all rations except R21. There was a general increase in passage with this ration. Data for the 346 other trials indicate that the rate of decline was more rapid for the high-grain rations than for the high-hay rations and that the rate of decline was least rapid when no grain was fed at all. The effect of frequency of feeding on the rate of decline was uncertain, being lowered with R5 and increased with R4. Of the conventional fractions studied the carbohydrates (crude fiber and N-free extract) were the only components not subject to extensive endOgenous addition. Thus, passage of these fractions through the upper gut should be clearly indica- tive of their digestion and absorption in that part of the tract. The output of crude fiber with different rations and frequencies of feeding is shown in Tables 54 through 40. Cor- responding values for the concentration of crude fiber in the ingesta on a dry matter basis are found in Appendix Tables 17 through 25. The mean and range of crude fiber passed from the duodenum per hour was 3 g. (l-7 g.) for R11, 15 g. (6-25 g.) for R21, lb g. (6-28 g.) for R22, 17 g. (6-42 g.) for R31, lz g. (5-zz g.) for RSz, 17 g. (6-56 g.) for R41 and 19 g. (6-29 g.) for R42. The patterns of passage for crude fiber were similar to those noted for the protein and ether extract fractions although they tended to be more variable. This was particularly the case with the high—hay rations. The mean quantity of crude fiber passed from the upper gut increased with increasing crude fiber intake, however, relative to 547 intake, preportionately less crude fiber was passed from the duodenum as the crude fiber in the ration increased. Mean passage was reduced by feeding the mixed rations twice daily but was increased by feeding only hay twice-a—day. On the other hand, more frequent feeding increased the range of out- put with Rb but decreased it with R5 and R4. The rates of passage of crude fiber through the upper gut are presented in Table 41. For the all-corn ration the rate was substantially lower than those for the other rations. Rate of passage of crude fiber increased as the amount of hay in the ration increased but the increases were disproportion— ate. Twice-a-day feeding reduced the rate of fiber passage with the mixed rations whereas it increased the rate with the all-hay ration. The passage of crude fiber declined in each trial follow- ing the initial starting time except with R21 in which it increased. The rate of increase with this ration was neg- ligible. Similarly, the rate of decline with R11 was very slight. The relative high rates of decline obtained with the remaining rations reflect rapid passage during the initial stages of the trials. This was particularly the case with Rae, R51 and R41. The rate of decline for crude fiber with these rations was almost directly related to the passage of this fraction during the first two hours of the collection. More frequent feeding reduced the high initial passage effect 548 and consequently reduced the rate of decline. The passage of N-free extract from the upper gut was more variable with time than any of the organic fractions studied. This was true not only for the total output (Tables 54 through 40) but also for the concentration of N-free extract in the ingesta (Appendix Tables 17 through 25). The mean and range of N-free extract passed from the duodenum per hour was as g. (ls-49 g.) for R11, 41 g. (17-82 g.) for R21, 45 g. (by-79 g.) for Rat, 58 g. (12—109 g.) for R51, 51 g. (11- 60 g.) for R55, as g. (15—60 g.) for R41 and 31 g. (lb-6O g.) for R42. The passage patterns for N-free extract were similar in most respects to the passage patterns of the other organic constituents. Passage of N-free extract was substantially lower with R1 than with the other rations. With R2, R5 and R4 the output of N-free extract decreased as the amount of hay in the ration increased. If the data are computed on a per-unit-intake basis, however, the output of N-free extract increased as the amount of hay in the ration increased. Mean passage was decreased by feeding R2 and R4 twice daily but was increased by feeding R5 according to the same regimen. The range of passage was narrowed by feeding the mixed rations twice-a-day. Feeding R4 twice daily did not alter the range of passage. Table 41 shows the rates of passage of N-free extract through the upper gut. The rate of passage with R11 was sub- 549 stantially lower than with any of the other rations. Passage with R2 was c5, 55 and 44 percent more rapid than passage with R5, R4 and R1, reSpectively. Thus, feeding hay and ground corn in combination accelerated passage of N-free extract Whereas feeding either one singly did not. Rate of passage was reduced by feeding the mixed rations twice daily but was increased by feeding only hay according to the same schedule. Table 4; indicates that passage of the N—free extract fraction also followed a decline with time for all rations except Rzl. The rates of decline were particularly notice- able with Reb and R51 and were reflections of rapid passage during the initial stages of the collections. Rates of de- cline obtained with R11 and R41 were similar while the rates obtained with R5; and R4: were lower and higher, reapectively. The influence of more frequent feeding on this fraction was not clear; rate of decline was reduced with R5 but was in- creased with R2 and R4. Although passage patterns for the organic components were similar for a given ration, the concentration patterns for these components were quite different. Concentration :patterns for each ration are shown in Figure 28. The protein content of the ingesta on a dry matter basis varied within a relatively narrow range. The largest spread between minimum and maximum values was 14 percent with R51 and the smallest Spread was 6 percent with R21. The range between minimum and 550 Figure 28. Effect of ration and frequency of feeding on the concentration of organic components in the ingesta (protein, 0 0; N-free extract, A A; crude fiber, 0 0; ether extract, 0 E Concumoflon N Coulee-mocha N Cocoon-ml.- ('4) 45 4O .. 35 ,_ 50 ,. 25 .. 20. ConconoQ-on ('5) .- 1 R" r. o-OVO’O-°‘:)G/( >o-2‘JN/Ko‘o‘e/‘KM ‘d/Nva’ \°_°‘ A’ ‘\./“‘\/r(\/“ o a WH-a‘ a D '8‘ IO ,_ a 9" H‘°~a-a—-ra vs 9‘ -o‘ 0 Mo‘opyo-¢-O‘°P o‘o-O'Ko/“o‘ozw 0’ .0 1 l 1 1 2 4 C U \ i. 20 22 24 D 20 22 24 45,. R2| .Oh wt ..‘—5’" \‘ / 3°» 4’ \.\{/ .._/ / 26.5... ° 20.. l5. .0. Wr.-°.°‘°\o-- o— 5 i i o‘ é -"“a -z -i- w- Timur.) 45 R3| 40).! ”- [“V\ 30, . 0‘2. :9b 20.. '5’ A. W 4-0—9- ,0_V W 5.Wm M 2 4 C C '0 3 I4 I. mun-d 45.. RM ”.- up 30. 25_ "wry 20,, O us. 0.0/ \o’°' \ [0,, {\V 0’ V (V\ 5 sqr°whoqh¢qrgarcdh-ir""**“h°*k" 1 l l 1 IO I2 l4 I. ".0 (NJ L 1 1 _1 I. 20 22 24 1 1 1 1 1 1 1 1 IO l2 I4 I. I. 20 22 24 TI" 1M.) Concentroflon m ConcoMnflon PL) Concumulon m U 0 30 20 45 ,. R22 40p 55L A /“\/ \A / Q 20.. l5._ 45 40 35 45 )- 0 . 0\0 a -:3’{W1MW 1 1 J 1 1 1 J__‘__‘__‘__J 2 4 6 I l0 l2 I4 I. I. 20 22 24 Timur.) 1 R32 ‘VV’VWX-.. ,0“ ,o’°’°\-re-’0 _ ”‘mmh‘a—MW 4 1 1 1 1 _1._ _1__l__.L J._L__._.L. 5.1 2 4 0 fl .0 l2 l4 IO 3. 20 22 24 Tin-chi.) 5 R42 : wwwx‘whwfihfm .fvw Wax/y .. W-o-O‘O-ra‘m‘a-n-o—a L J 1 L J l ,__L_4__J_J_J 2 4 6 0 IO I2 14 I6 8 20 22 24 Tin-HM.) 552 peak values appeared to be somewhat greater with the high-hay rations than with the high-grain rations. Nevertheless, there was not much difference between rations in the average protein content of the ingesta. The average protein content of the ingesta on a dry matter basis was 54% for R11, 25% for R21, 5lp for R22, 27% for R51, 27% for R52, 29% for R41 and 26% for R42. The average concentration of protein in the ingesta was considerably higher in every case than the concentration in the corresponding ration. With each ration the protein content of the ingesta increased throughout the digestion cycle (24 hours). Frequency of feeding appeared to have no appreciable effect on the protein percentage of the ingesta. The percentage of ether extract in the ingesta on a dry matter basis remained remarkably constant throughout the diges- tion cycle with each of the rations. The maximum variation in concentration occurred with R11; it deviated only 5 percentage units in 24 hours. Ingesta for the remaining rations showed changes which varied from 1.0 to 2.5 percent. Distinct trends were noted for changes in the concentration of ether extract in the ingesta with different rations and frequencies of feed- ing. The concentration declined slightly during the cycle with R11 whereas it increased very slightly with R51 and R41. With Rzl, Rea, R52 and R42 the percent of ether extract in the ingeSta remained relatively steady. On a dry matter basis the average content of ether extract in the ingesta was 11.7% 355 for Rll, 8.4% for Rzl, 8.5% for Rib, 7.0% for R51, 7.1% for Roz, 6.0% for R41 and 5.6% for R42. With Rll the concentra- tion of ether extract in the ingesta was about h.5 times the level in the ration. The concentration in the ingesta with the other rations was approximately doubled. Frequency of feeding was of little influence on the average percent of ether extract in the ingesta. On a dry matter basis the average percent of crude fiber in the ingesta was 4.1 for Rll, 10.6 for R21, 8.9 for R22, 14.5 for R51, 11.9 for R52, 14.6 for R41 and 17.1 for R42. Concentrations in the ingesta for the high-grain rations were in excess of the correSponding ration levels whereas ingesta concentrations for the high—hay rations were less than the corresponding ration levels. The concentration patterns for this fraction were similar to the passage patterns though they appeared to be somewhat less variable. The variations seemed to increase, however, as the amount of crude fiber in the ration increased. Despite these variations there was a gen- eral tendency for the concentration of crude fiber in the in- gesta to decrease slightly with time. Twice-a—day feeding lowered the average concentration of crude fiber in the in- gesta with the mixed rations but increased it with the all- hay ration. The range between minimum and maximum concentra— tions was narrowed in each case by feeding the rations twice daily. 354 The concentrations of N-free extract in the ingesta varied widely for a given ration with the exception of those for the all-hay rations. Ingesta N—free extract for these rations (R41 and R42) varied over a range of only 5 percent outside of one low value (19%) for R41 and one high value (41%) for R4h. Interestingly enough, both of these values were for the initial hour of collection. It is also noteworthy that the ranges of concentration for the remaining rations were quite similar, the minimum value being 25% (Eb-27) and the maximum value being 45m (58-45). The average concentration of N-free extract in the ingesta passed during a digestion cycle was 51% for R11, 54% for Rzl, 55% for Rz2, 52% for R51, 5h% for R52, 26% for R41 and 28% for R42. In each case the average concentration was substantially below the corresponding ration level. R2 resulted in the highest average concentration of N-fgee extract in the ingesta and was followed in order of decreasing levels by R5, R1 and R4.. Both mixed rations re- ‘sulted in higher average concentrations than the rations in which the feeds were fed singly. Twice-a—day feeding appeared to have little influence upon the N-free extract content of the ingesta. 555 Discussion Quantitating digestion in the various segments of the alimentary tract is considerably more difficult than estima- tion of the extent of digestion for the entire tract. As was pointed out previously, this is particularly true for the reticulo-rumen and omasum. Until recently, the only estimates of the extent of digestion in the reticulo-rumen were those based on measurements obtained indirectly. Digestibilities were computed by means of the lignin—ratio technique which was applied to samples obtained from (1) fistulated animals by complete removal of the contents, (2) ligated segments of the gut of slaughtered animals and (5) the reticulum in close proximity of the reticulo-omasal orifice of fistulated animals. The validity of the results obtained by any of these pro— cedures depends upon the samples being representative of the ingesta passing through the reticulo-rumen during the entire period of a feeding cycle. The use of a re—entrant duodenal fistula to directly measure ingesta passing from the upper gut offers a more precise method for obtaining quantitative measurements of the disappearance of food from the tract and of the appearance of synthesized products that are not digest- ed or absorbed before they reach the lower gut. It is gen- erally felt that a direct measurement is preferable to a cal- culated (indirect) one. In adapting the re-entrant fistula technique to the 556 partition of digestion in the upper and lower gut, it is necessary that the technique satisfy reasonably well the points of validity mentioned earlier in the text. Available evidence indicates the first two assumptions are essentially correct. A basis for assuming that output from the upper gut on any given day is representative and equivalent to the out- put on any other day, or that output from the upper gut with continuous re-introduction is equivalent to passage from the upper gut in the intact alimentary tract has not been defi- nitely established. However, unpublished data (McGilliard, 1956) indicate that both of these assumptions are essentially correct. The rations used in this part of the study were intended to maintain dry matter intake at a relatively constant level but to vary the physical makeup and composition of the ration over as wide a range as possible. This was done in order to determine the role these factors play in passage of ingesta from, and the extent of digestion in the upper gut without confounding the results with the effect of level of dry matter intake. Upper gut digestibilities were determined directly by collecting all ingesta as it passed the duodenum. Total digestibilities were determined expediently by using Cr205 as an inert marker although it was realized that the results obtained by the use of this material are subject to a number of criticisms. Lower gut digestibilities were calculated by 357 difference. It should be made clear before proceeding further that the coefficients of digestibility obtained in this study for the upper gut may reflect, depending upon the analytical frac- tion, processes other than those of breakdown and absorption. For example, among the conventional fractions a coefficient for the carbohydrate fractions (crude fiber and N-free ex- tract) would be almost entirely the result of digestion and absorption. On the other hand, a coefficient for protein (expressed as N) would indicate the balance between dietary intake and the processes of breakdown, absorption, addition and synthesis. Similar complications would occur with the ether extractable and inorganic fractions. These discrep- ancies are also true of the coefficients of total digesti- bility and should not make the results any less valuable in estimating the extent of the activities which take place in the upper gut as long as the terms of reference are understood. The coefficients of digestibility in the present experi- ment indicate that 25-55% of the dry matter was lost in the upper gut and an additional 25-48% disappeared in the lower gut. On the average 52% of the total digestion of dry matter occurred in the upper gut. It should be pointed out, however, that this value was uncorrected for the endOgenous protein, ether extract and ash which were added to the ingesta in the upper gut in rather appreciable quantities, particularly with 558 the high-corn rations. If corrections are made for these additions and the digestibilities are computed on the basis of dietary intake only, the losses of dry matter in the upper gut ranged from 58-65% and an average of 67% of the total digestion occurred in the upper gut. In order to make this calculation, it was assumed that no digestion in the upper gut occurred for any component whose output from the duodenum exceeded its dietary intake. This assumption is in all prob- ability not entirely correct, for it seems more likely that the output was a balance in excess of the amount of dietary material which was removed. Dry matter digestibilities for the reticulo—rumen very sinilar to the uncorrected values obtained for the upper gut in this study have been reported by Balch (1957) for cows (26—62%) and by Gray g3 g1. (1958a) for sheep (55—60%). Moreover, it is noteworthy that these values were obtained by two different methods which were com- pletely independent of the one used in the present eXperiment. There was a general tendency for the coefficients of total digestibility for dry matter to increase as the proportion of corn in the diet increased. On the other hand, whereas dry matter digestibility in the upper gut was highest with corn alone (55%), it was lowest with the high corn-low hay diet (25%). Dry matter digestibility with the high-hay diets were similar (55-56%). Thus, with the exception of the diet com- posed entirely of corn, proportionately less of the dry matter 559 was digested in the upper gut and proportionately more was digested elsewhere as the amount of corn in the diet was in- creased. This finding is in direct contrast to Balch's data (1957) which indicates that proportionately more dry matter was digested in the reticulo-rumen of cows as the amount of concentrate in the diet was increased. The differences be- tween dry matter digestibilities of the various rations in the present study suggest that undigested dry matter passed more rapidly from the upper gut with the mixed rations than with corn or hay alone. This also holds if the values are adjusted for endOgenous addition, although there is little difference between values for the mixed diets as a consequence. According to Hale g3 g1. (1947a, 1947b) and Gray 23 gl. (1958a) only well digested material leaves the reticulo-rumen and passes on down the tract. That this was not the case in the present study is illustrated by the coefficients of digesti- bility for the residues which entered the lower gut. Residue digestibilities ranged from 64flifor corn alone to 57 and 50% for the mixed diets to 42% for hay alone. However, it should be pointed out that the rations employed by both Hale gt g1. and Gray g3 g1. were composed entirely of hay and as a result, were considerably more uniform in their consistency than the mixed rations employed here. The ingesta of animals fed on mixed diets containing materials of widely different densities probably should not be expected to behave in the same way. 560 On the other hand, it is quite apparent that considerable digestion of the residues of both the corn and hay diets took place in the lower gut. The influence of frequency of feeding on dry matter digestion in the upper, lower or tOtal gut was inconsistent and thus, inconclusive. Large differences, however, were not expected in View of (l) the relatively low level of dry matter intake and (a) the limited nature of the data. Partition of the digestion of organic matter between the upper and lower gut yielded results which behaved similarly to those for dry matter, but were not influenced to as great an extent by the addition of endOgenous materials to the in- gesta. Coefficients of digestibility indicate that 54-63% of the organic matter was lost in the upper gut and an additional ld-59fi disappeared in the lower gut. On the average, 65% of the total digestion of organic matter occurred in the upper gut. If corrected for endOgenous addition, the losses of organic matter ranged from 65-79% and an average of 70% of the total digestion occurred in the upper gut. Again, as for dry matter, there was a tendency for the total digestibility of organic matter to increase as the proportion of corn in the diet increased. In contrast, with the exception of the diet consisting of corn alone, proportionately less of the organic matter was digested in the upper gut as the amount of corn in the diet was increased; proportionately more was 561 digested in the lower gut. Explanations of these tendencies are apparent when fractions making up the organic matter are taken into consideration. Values for the digestion of protein (Nx6.25) in the upper gut indicate that considerable nitrogen was added to the in- gesta in this segment of the tract with the high—corn diets. The amount added ranged from 159 to 592 g. over a period of z4 hours. Endogenous nitrogen may arise from several sources. Saliva may contribute to the rumen ingesta a substantial amount of nitrogen of which approximately 70% is in the form of urea (McGilliard, 1956; Johns, 1957; Somers, 1957). Studies by Houpt (1958) indicate that the transfer of urea from the blood to the ingesta through the rumen wall may be an even more im- portant source of endogenous nitrOgen than the saliva, par— ticularly with high-energy, nitrogen-poor diets. Houpt (1959) subsequently reported data which showed that in sheep fed timothy hay, starch and sugar the amount of urea nitrogen passed into the rumen through the rumen wall was 4.9 m mol./hr. as compared to only 0.5 m mal./hr. in the saliva. The ability of ruminants on low-nitrOgen diets to conserve nitrogen by decreasing the excretion of urea via the kidneys has been demonstrated by Schmidt-Nielsen gt El- (1957), Schmidt-Nielsen (1958) and Houpt (1958). Moreover, Houpt (1959) has shown the importance of dietary starch in the subsequent utiliza- tion of the urea which was conserved. The influence of starch 562 on the utilization of dietary urea by microorganisms of the rumen has been repeatedly demonstrated. Additional nitrOgen may be derived from sloughed epithelial tissue in the upper gut and from the secretion of gastric Juice in the abomasum. Hogan (1957) estimated that about 0.6 g. of nitrogen was se- creted into the abomasum of sheep each 12 hours. These sources appear unimportant, however, when compared to saliva and trans- fer into the rumen through the rumen wall. In contrast, a net loss of nitrogen was observed in the upper gut with the high-hay, low-corn diet (5.8%) and with hay alone (15.6%). Thus, it appears that the level and source of dietary nitrogen as well as the dietary carbohydrate are intimately involved in determining the net loss or gain of nitrOgen in the upper gut. Under the conditions of this ex- periment the dividing line between gain or loss was a dietary crude protein level of approximately 15%. Balch (1957) found that the apparent digestion of protein in the reticulo-rumen was low with diets consisting mainly of roughage and contain— ing only small amounts of protein. In contrast, diets con- taining large amounts of protein in the form of groundnut cake showed evidence of a considerable loss (l2-54i) of the dietary nitrOgen. Evidence of even larger losses of nitrogen from the reticulo-rumen of sheep fed different hay diets has been reported by Gray and Pilgrim (1956) and Gray gt El- (1958b). These authors found that 40-60p of the dietary 365 nitrogen was lost in the reticulo-rumen of sheep fed diets containing more than 11% protein whereas endogenous nitrogen was added to the ingesta when the diets contained less than 7» protein. Direct evidence confirming that considerable dietary nitrogen is lost in the upper gut under certain con- ditions has been obtained by HOgan (1957). Values for the digestibility of protein in the lower gut indicate that much of the dietary as well as part of the endo- genous nitrOgen was removed in this segment of the tract. The amount digested ranged from 46-128% and accounted for more than 70% of the total. If considered on the basis of the nitrogen entering the lower gut (dietary and endOgenous) approximately 70» was digested. Similar results have been obtained by Balch (1957) and Hogan (1957). It is probable that these values underestimate the extent of nitrOgen removal in the lower gut for Raynaud (1955a), Boyne g3 El- (1956), Badawy gt §l° (1957), HOgan (1957) and Rogerson (1958) have indicated that a considerable amount of endOgenous nitrogen is secreted into the proximal small intestine in addition to the nitrOgen added to the ingesta in the upper gut. In fact, Hogan (1957) estimated that about 10 times more nitrOgen was secreted into the small intestine than was secreted into the upper gut. All are agreed, however, that most of the diges- tible nitrOgen has been removed before reaching the cecum. It seems reasonable to conclude, therefore, that the small 364 intestine is the primary site of nitrogen removal under most circumstances. To what extent and under what conditions nitrogen is recycled through the digestive tract would appear to be of fundamental importance in understanding nitrogen digestion in ruminants. With non-ruminant animals there is considerable evidence to suggest that little of the fecal fat is of dietary origin. The data of Balch (1957) and ROgerson (1958) indicate that this is also true with ruminants. Results obtained by Hale (1969) suggest this material is non—fat in character. There is also evidence that a substantial amount of ether extract- ible substances of non-dietary origin is added to ingesta in the reticulo-rumen (Hale g3 gl., 1940, 1947b; Chance 23 El., 1956; Rogerson, 1955). Hale g3 él- (1940, 1947b) were of the opinion that this addition was due to the synthesis of fats by the rumen microorganisms. However, Garton and Oxford (1955) were unable to demonstrate synthesis of polyethanoid 618 fatty acids by rumen bacteria of sheep fed on hay. Recent evidence presented by Habel (1959) indicates that a considerable amount of lipid material (predominantly triglycerides) is normally found in the stratum corneum of the rumen epithelium. In view of this, it seems probable that significant quantities of these lipids are continuously added to the ingesta by epi- thelial desquamation. Results of the present experiment indicate that the total 365 digestibility of ether extract (40-82%) increased as the amount of corn and level of fat in the diet increased. This is in agreement with available evidence regarding the effect of source and level of dietary lipids on their digestibility. 0n the other hand, negative values were obtained in every case for the digestibility of ether extract in the upper gut. The amount of ether extractible substances added to the in- gesta ranged from 29-95 g. in :4 hours and, in general, tended to increase as the amount of corn in the diet increased. These results suggest there was no digestion of lipids in the upper gut. In the classical terms of reference regarding digestion this is probably true, for there is no available evidence which indicates long—chain fatty acids liberated by glyceride hydrolysis, or glycerides pg; fig are absorbed from the upper gut. However, if degradation or alteration of the components which make up the ether extract fraction are considered, then this is not the case. According to Garton (1960) rumen micro- organisms can not only hydrogenate unsaturated fatty acids but also hydrolyze dietary glycerides and phospholipids. In some instances, this hydrolysis has been found to be rather extensive. Although little is known about the digestion and absorp— tion of lipids in the ruminant intestine, it is quite apparent from results of the present investigation that the intestine was the principle site wherein these activities took place. Loss of ether extract from the ingesta in the lower gut account— ed for all of that removed in every case. Moreover, a compari- son of the digestibility coefficients for the ether extract entering the lower gut (55-84m) with those for the entire gut (40-85%) suggests part of the endogenous lipids was removed in addition to a considerable portion of the dietary lipids. To what extent the endOgenous lipids (from the upper gut) and dietary lipids were removed can not be determined from the parameters of the experiment. However, if further endogenous addition of ether extract did occur in the lower gut (Balch, 1957; Rogerson, 1958), it is probable that their actual re— moval is grossly underestimated by the values given above. A comparison of the digestibility values obtained by Balch (1957) for ether extract with those obtained here is of considerable interest. In Balch's eXperiment, the average digestibility of ether extract in the reticulo—rumen for a wide variety of diets was 58% while that for the remainder of the gut was 9%. Only with three of the diets did digestion posterior to the reticulo-rumen exceed that in the reticulo- rumen, and two of these diets consisted of equal parts of ground hay and concentrates. In contrast, the digestibility of ether extract in the upper gut in the present study aver- aged -55%Swhereas that for the lower gut was 100%. Moreover, the digestibilities for the lower gut were consistently and markedly higher than those for the total gut. The cause for 367 this discrepancy between methods for this fraction is not clear as the results obtained for the other fractions were quite comparable. The role of the reticulo-rumen in carbohydrate digestion (N—free extract and crude fiber) is well recognized though quantitative estimates of the extent of such digestion are rather limited. Direct estimates for the upper gut were ob- tained in the present experiment, and these lend further emphasis to the importance of this segment of the gut in car- bohydrate digestion. An average of 62% of the dry matter con- sumed by the steer was in the N-free extract fraction and 16% was in the crude fiber fraction. Thus, carbohydrates consti- tuted about 78% of the dry matter intake. Crude fiber digestibility in the entire gut ranged from -ze to 46%, and where comparisons were possible, these values agreed well with the digestibility figures reported by Schneider (1947) for intact cows. Crude fiber removal in the upper gut accounted for all of the digestion of this fraction which took place. Upper gut digestibilities ranged from 14-57% and in gneral decreased as the proportion of corn in the diet in- creased. The depressing effect of large amounts of soluble sugars and starch on the digestion of crude fiber has been repeatedly demonstrated (Head, 1955; Balch, 1957; Rogerson, 1958). Crude fiber digestion in the upper gut was greater in every case than digestion in the entire gut. This suggests 568 that crude fiber was accumulated at some point in the lower gut. The digestibility values for the crude fiber residues entering the lower gut support this contention, for they were negative with each diet. Similar results have been obtained by Kameoka and Morimoto (1959) with goats which had the flow of ingesta exteriorized at the omaso-abomasal orifice. In contrast to the negative values obtained here, Balch (1957) found that the amounts of crude fiber digested in the reticulo-rumen did not always exceed those digested in the lower gut. In cows the digestibility of crude fiber varied from -8 to 61% in the reticulo-rumen and from 15-47% in the lower gut. There was a general trend for the introduction of increasing amounts of concentrates to depress the digestibil- ity of crude fiber in the reticulo—rumen, but as a consequence, the prOportion of crude fiber digested elsewhere in the gut was raised. Similar data has been reported by Rogerson (1958) for sheep. The fact that no digestion of fiber occurred in the lower tract in this study lends credence to the hypothesis that only well digested material leaves the reticulo-rumen (Hale, 1959; Gray g3 gl., 1958a). Furthermore, it appears reasonable to assume this would more likely occur with crude fiber than with any other'fraction since there is ample evidence to indicate finely divided feeds and soluble feeds pass rapidly from the rumen whereas passage of the fibrous feeds, which have not 569 been broken down to a fine consistency, is mechanically re- tarded. The discrepancy between values obtained directly (KameOka and horimoto, 1959; the present eXperiment) and in- directly (Balcn, 1957; Rogerson, 1958) with somewhat compar- able rations is difficult to reconcile, but it would seem to be a result of the sampling technique. Resolution of the problem appears to await the simultaneous determination of digestibility in the same animal by both the direct and in- direct method of sampling. The digestibility of N-free extract in the entire tract ranged from 66-9lw and in general increased as the amount of corn in the diet increased. Digestion in the upper gut, which ranged from 59-8bh, accounted for more than 75» of the total. The value for digestibility of the N-free extract of corn alone was considerably greater than those for the other diets; values for the digestibility of this fraction of the mixed diets and hay alone were similar (coefficients for hay alone were slightly but not significantly lower). Consequently, the digestibility of N-free extract in the lower gut (a-zi%) was greater for the mixed rations (lé-zlfi) than for corn or hay alone (B-lOfi). Furthermore, the results indicate that, with increasing amounts of hay in the diet, the prOportion of R-free extract digested in the upper gut increased and the amount digested elsehwere decreased (excluding corn alone). Although the ranges of digestibility agree well with those 570 obtained by Balch (1957) for the reticulo-rumen (45-76fi) and the lower gut (T-zzfi), the effect of increasing the amount of hay in the diet on the proportion of N-free extract digested in the upper and lower gut is in direct contrast to the re- sults obtained here. According to available evidence concentrates leave the reticulo-rumen of cows more rapidly than hay (Balch, 1950; Paloheimo and hakela, 1959). Loss from the reticulo-rumen may result either from digestion and absorption or from pas- sage of the undigested residues to the lower gut. The extent to which either occurs will depend upon the length of time the food remains in the reticulo-rumen and the susceptibility of the food to digestion. Since the digestible carbohydrates in concentrates are more readily attacked in the reticulo~rumen than the fibrous carbohydrates in hey, it seems reasonable to expect that the carbohydrates in corn will be digested to a greater extent there than the carbohydrates in hay. 0n the other hand, the carbohydrates in corn will also have a ten- dency to leave the reticulo-rumen more rapidly than those in hay by passing to the lower gut. Thus, the residues may escape fermentation in the upper gut and become vulnerable to diges- tion in the lower gut. Results of the present eXperiment, particularly for the mixed diets, suggest a considerable amount of undigested corn was passed from the reticulo-rumen. Evidence for this is 571 (l) the higher digestibility of the N—free extract which entered the lower gut with the diets containing corn and (z) the greater quantities of N-free extract which were passed to and subsequently digested in the lower gut with the mixed diets. The presence of hay in the diet appeared to be neces- sary for the rapid passage of corn from the upper gut. It is also probable, in view of the well known effect of level of intake on rate of passage, that even proportionately greater amounts of corn would pass to the lower gut if the level of intake of the mixed diets were increased considerably. The rapid passage of undigested corn from the upper to the lower gut has interesting implications. It may provide, at least in part, a basis for understanding the commonly held belief that a unit of TDN in hay is less productive than a unit of TDN in concentrates. Those who support this view feel that the difference in reSponse is eXplained on the basis that more energy is dissipated as gases and as heat of fermentation in the digestion of roughages than in the digestion of concen- trates. The calorimetric data reviewed by Reid (1956), however, do not support this eXplanation. In fact, the data indicate that the loss of energy as methane and as heat of fermentation can be somewhat greater for concentrates than for roughages. 0n the other hand, results of the present study imply that under certain conditions not all of the carbohydrate in the diet is fermented to volatile fatty acids in the reticulo- 572 rumen, but that a substantial amount is degraded to glucose in the lower gut. (It is provisionally assumed that the diges- tible N-free extract passed to the lower gut was composed, for the most part, of the starch of corn.) Supporting evidence for this hypothesis has been obtained by Fries and Conner (1959), who estimated that approximately 500 g. of glucose per day were absorbed from the lower gut of a 500 pound Hol- stein calf in which a portal cannula and exteriorized carotid had been established; the ration employed was composed of 8.0 lb. of alfalfa hay and L.5 lb. of ground corn. There is little doubt that the steam volatile fatty acids are utilized less efficiently than is glucose in the cycles of intermediary metabolism (Armstrong and Blaxter, 1957a, 1957b; Armstrong gt gl., 1957, 1958). Hence it appears reasonable to assume that the efficiency with which the energy of the absorbed nutrients is used will vary according to the proportion of steam volatile acids and glucose in the end products of diges— tion. Clearly, more work needs to be done to elucidate this relationship. Values for the total digestibility of ash were highly variable and demonstrated that with it, more than with any other fraction, the results were influenced by processes other than true digestion. Negative values were obtained in every case for the digestion of ash in the upper gut. The amounts of ash added to the ingesta ranged from 202-594 g. per day, 575 and with the high—corn rations they exceeded the dietary intake whereas with the high-hay rations they were less than the dietary intake. Furthermore, the amount of ash of endogenous origin tended to increase as the dietary intake of ash de- creased. Similar results have been obtained by Hale (1959), Boyne Q; g;. (1956), Balch (1957) and Rogerson (1958). There is little doubt from the evidence available that a major por- tion of the ash of endogenous origin in the upper gut is de- rived from the saliva and gastric secretions. It is entirely possible, however, that the transfer of inorganic materials through the wall of this segment of the gut may assume con- siderable importance under some conditions. Little work on this latter aSpect of digestion has been performed with rumi- nants. It is clear from the coefficients of ash digestion for the lower gut that a substantial amount of both the dietary and non-dietary ash was removed in the intestinal tract. In fact, the amount removed in the lower gut exceeded the dietary intake in every instance. There did not appear to be any re- lationship, however, between the extent of ash absorption and the dietary intake or quantity of ash which was passed to the lower gut. The intensive absorption of ash in the intestinal tract also has been demonstrated by Boyne g3 El. (1956) and ROgerson (1958) with sheep and by Balch (1957) with cows. In contrast to absorption, inorganic salts enter the intestinal 574 tract in the bile and pancreatic secretions (Babkin, 1950). Becuase of the continuous secretion and absorption of inorganic materials throughout the gut values for the digesti- bility of ash in the various segments are obviously only bal- ances and give no reliable indication of the extent to which these processes occur. In relating rate of passage of ingesta or its separate Components to the coefficients of digestibility Obtained for these fractions, it should be pointed out that the design of the procedure itself dictates the relationship which must exist. Since the ingesta collected is a direct determination of the residues whicn have not been digested or absorbed in the upper gut, it follows that the rate of passage must be inversely related to digestibility providing the original premise holds that input equals output over each bé—hour period. Thus, as digestibility increases, the quantity of residues left for passage down the tract decreases and the rate of passage likewise decreases. Hoaever, a discussion of the data is perhaps pertinent regarding the time-factor rela- tionships whicn affect digestion. According to Balch (1956) cows begin to drink water some- time after the commencement of eating and continue to do so at intermittent intervals as long as eating continues. Again, cows frequently were observed to take several drinks after the end of a meal. A similar pattern of drinking was observed 575 in the present study. The number of periods spent drinking were approximately the same for all diets. host of these periods were interspersed between periods of eating during the terminal stages of the meal or were concentrated within a short Span of time i mediately after the meal was finished. The distribution of periods suggests that water was consumed, for the most part, during the early part of the collections, and that the ingesta was diluted accordingly. Daily water intakes (o.c-6.d gal.) with the various rations were similar to those (5.9-4.5 gal.) estimated by Winchester and horris (1956) for steers maintained under comparable conditions. Further agreement between the results Obtained here and those reported by winchester and horris is seen in the fact that the intake of water tended to increase as the dietary intake of protein and ash increased. If there was a relationship between water intake and the passage of ingesta from the upper gut at any given time or total passage, it was not reflected by any of the parameters of the experiment. Water intake appeared to be related to the passage of ingesta from th upper gut only insofar as it influenced the concentration of dry matter in the ingesta. The irregularity of defecation under normal feeding con- ditions is well known. As a result, little uniformity in daily fecal output is eXpected even though the ditary intake is constant. In the present study the periods of defecation were distributed more regularly throughout the day than is 376 usually the case, and the day to day fluctuations in fecal output were markedly reduced. It is probable that the pattern of feces excretion was influenced to a large extent by the daily routine whicn was followed throughout the entire eXperi- ment. Ritzman and Benedict (lgzé) have indicated that urinary excretion is a function of protein intaie. Steers on high protein allowances excreted more urine than did comparable animals on low protein diets. A similar trend was observed in the present study, for urinary excretion had a tendency to increase as the dietary intake of protein increased. Urinary excretion also appeared to be influenced to a certain extent by the amount of water consumed. The interrelationship between water intake, protein intake and urinary excretion, however, is not entirely clear. The cuase of the increased urinary excretion as a result of once-a-day feeding is also obscure. Available evidence indicates a number of lFCtOPS influence the amount of time required for the ingestion of a ;eal. Of these, the degree of hunger of the animal and the quantity and physical makeup of the diet are of considerable importance. (0 ,a‘ A According to Balch (1 be), after a meal is placed before them, cows will eat steadily until most of the meal is consumed, after which eating beCOmes Sporadic and interSpersed by drinks of water. The pattern of eating in this experiment (excluding the all-corn diet), when the total meal was offered at a single 577 feeding, was very similar to that indicated by Balch. With more frequent feeding of smaller amoants, however, the animal continuously ate until the ration was cleaned up. Thus, the actual time and the Span of time spent eating the total ration was markedly reduced by twice-a-day feeding. Again, excluding the all-corn diet, little difference was observed between diets in t;e amount of time and Span of time Spent eating for a given frequency of feeding, although there was some sugges— tion that eating was less rapid as the amount of hay in the diet increased. A similar inference is found in data presented by Schalk and Amadon (1958) and Balch (1958). With the all- corn diet, eating was considerably prolonged and appeared to be somewhat listless in comparison to that with the other diets which were fed. Due to their relatively low level of intake, it is prob- able that hunger was an important factor in the rapid inges- tion (lo-15 lbs./hr.) of the mixed diets and the all—hay diet, particularly where the diets were divided and fed twice daily. Even ingestion of the all-corn diet, which was slow compared to the other diets, was rapid compared to the value (5 lbs./ hr.) obtained by Balch (1958) for cows offered hay 3g libitum. Because the various rations were consumed at similar rates for a given frequency of feeding, it seems unlikely that any marked differences in the passage patterns between rations could be attributed to the time Spent eating pgr 5g. The amount of time Spent in rumination during a feeding 578 cycle varies considerably in different animals and with dif— ferent rations. Under conditions in which a major part of the diet was composed of hay, estimates of the daily rumination times for cattle on approximately maximum levels of intake have varied from 5—8 hr. Similar results for sheep have been re- ported by Gordon (19a8a). In the present study the amount of time Spent ruminating with the high—hay diets was somewhat less than the figures given above. It is probable that the relatively low level of intake, supple nature of the hay and age of the animal contributed much toward this apparent reduc- tion in rumination time. In general, the periods of rumination in sheep and cattle are distributed throughout the day and, if undisturbed, there is a tendency for both Species to show a preference for rumin- ating in the early hours of the morning (Schalk and Amadon, H 9L5; Gordon, 19588). Similar patterns of rumination were Observed in the present eXperiment, although no particular preference for ruminating was indicated for any Specific period during the day. It seems likely that this latter effect was mediated by the very nature of the collections themselves. Detailed studies of rumination in sheep indicate the time when rumination occurs and the amount of rumination appears to be independent of any time-relationship with eating (Gordon, (C‘ 1‘38c). This is illustrated further here by the similarity in distribution of periods and amount of time Spent ruminating with a given ration fed at different frequencies of feeding. 579 According to Gordon (1958a) rumination time in sheep is relatively constant from day to day. horeover, the amount of rumination does not appear to be dependent upon the quantity of roughage ingested, except when the diet fed is nearly roughage—free. Rumination was reduced slightly, but not sig- nificantly, when one-third of the total diet consisted of hay and was reduced markedly when only concentrates were fed. The least amount of hay fed in the present study was 50% of the total diet, and the time Spent ruminating with this particular diet was reduced to about two-thirds of that observed with the high-hay diets. Rumination was completely abolished when the entire ration was composed of corn. The effect of rumination on passage from the upper gut will be conmented upon later in the discussion. hany of the factors which influence emptying of the upper gut have been commented upOn previously in a discussion of the preliminary results. Similarly, criticisms of the continuous method of collection as it applies to the estimation of out- flow have been pointed out. The factors affecting flow during the S-hour preliminary collections undoubtedly also apply to the flow of ingesta obtained here. Irregular but frequent passage of ingesta from the upper gut took place throughout each collection. Flow was accelerated when ingesta was not returned to the lower gut; when ingesta was re-introduced, flow was reduced or inhibited for a period of time. The dura- tion of tcis effect seemed to be related to the quantity of 580 ingesta re—introduced. Flow of ingesta occurred in every sanpling period except three and in this regard was more con— tinuous than the flow observed in sheep fitted with multiple fistulae (Phillipson, lgbba). In a later study (Hogan and Phillipson, 960) tne_flow of ingesta in sheep fitted with re-entrant fistulas nore nearly resembled the pattern of flow Obtained in the present study. The primary difference between the two studies with sheep, other than the types of fistulae employed, was the method of re-introduction of ingesta into the lower gut. In the initial study, ingesta was re-introduced into the lower gut in large amounts at infrequent intervals 4 $- ‘V whereas in the later Study, ingesta was returned in Small amounts almost continuously. These results, as well as the results obtained in the present eXperinent, serve to emphasize further the effect of reaintroduction of ingesta into the lower gut on flow from the upper gut. The valid estimation of flow must avoid not only excessive flow thr ugi failure to return iniesta, but also reduced flow caused by the return of large volumes of ingesta at one time. Therefore, in this study an attempt was made to approximate flow in the intact gut by introducing a volume of ingesta into the lower gut equal to and at the sane rate as that which was collected. However, this technique prevents the peristaltic-antiperistaltic move- nents of inLesta that can be observed with the U-tube ip situ. As a result, outflow from the upper gut is not subject to the 581 effects of a hydrostatic pressure such as exists intraduo— denally. According to Phillipson (lQCZa) passage of total ingesta from the upper gut was much more continuous after a feed of meals than following a feed of hay. The results obtained in tre resent study do not seem to support this view, for flow did not appear to be any more continuous with one diet than with another. In fact, considerable variation in flow between sampling periOds occurred with eacn diet. However, the ampli- tude of the variations tended to be somewhat greater with the mixed diets. Flow during eacn collection (excluding 321) was initially high and declined thereafter. It is probable that the high initial flow was related, at least in part, to eating (preliminary experiment; Balch, 1955) for dividing the ration and feeding it twice daily noticeably reduced the initial flow. On the other hand, no increase in flow was noted in relation to the second eating period (ax-feeding), although the decrease in flow following the first eating period was attenuated somewhat. TJiS perhaps would not be the case at higher levels of intake. The possible influence of the collec— tion procedure on initial flow has been pointed out in the pre— liminary experiment. The flow of ingesta, which increased rather than declined after feeding with Rel, was unusual in comparison to flow during the other collections. This collection was preceded by a period in which the animal was slightly bloated. Ingesta in 582 the U-tube was frothy in nature and appeared to pass through the tube at more infrequent intervals than was usually observed with ingesta of normal consistency. Although visible disten— tion of the animal had subsided before the collection was made, the ingesta passing from the upper gut was still ex- tremely frothy and a considerable amount of free gas was emitted during the course of the collection. Distention of the duodenum or small intestine is known to inhibit emptying of the stomach (Alvarez, 1940; Phillipson, 1952a). One might Speculate frothy, gassy ingesta passing to the lower gut would produce distention and exert a similar effect. If this was indeed the case with R21, then it is probable that ingesta accumulated in the upper gut to a certain extent, thus dis- rupting the basic premise that input equals output over each L4—hour period. Since distention of the lower gut by frothy, gassy ingesta was eliminated by the collection procedure, it seems reasonable to eXpect that the rate of emptying of the upper gut, particularly as the collection prOgressed, would increase to Compensate for the buildup of ingesta in that part of the tract. Assuming this is a valid explanation of events, one might question the role of the'lower gut in the etiology of bloat. According to Asn Chkéa, 1959b) the acidity of the abo- masal contents flowing into the duodenum fluctuates only within narrow limits in individual sheep under extremes of 385 feeding and fasting. It appears from the results of this study that a similar constancy exists with widely different diets and different frequencies of feeding. horeover, there does not appear to be any obvious relationship between pH and flow of total ingesta or passage of solids. Thus, the infer— ence drawn from Ash's data, that inflow, abomasal secretion and outflow are coordinated, seems to be essentially correct. If this is indeed the case, then the passage of ingesta from the abomasum is a direct reflection of the passage of ingesta from the reticulo-rumen and omasum. The mean pd values (1.80— a.sv), which are considerably below those reported in the literature for sheep, perhaps reflect a Species difference between cattle and sheep. With the diets used in this study 54.8—79.9 liters of ingesta passed from the duodenum in e4 hours. This represents the passage of about 55-77 liters of water from the duodenum. The total volume of fluid consumed each L4 hours in both the food and the drinking g water ranged from lo-LE liters. Thus, tnere was a net increase of 58—54 liters of water in the gut between the mouth and the proximal duodenum. It is probable that this volume is more than accounted for by saliva and gastric juice. For cows receiving a variety of diets Scerbakov (1958) estimated that 8.5-14.7 liters of digestive secretions ( saliva and gastric juice) per kilogram dry matter intake were added to the ingesta each day. If these values are applied 584 to the dry matter intake of the diets used in the present study, computed values (43-57 1.) very similar to the actual values (SB-54 l.) for net increase of water in the upper gut are obtained. In the preliminary experiment passage (flow) was calcu- lated and eXpressed as mean passage, rate of passage and rate of increase or decline. The data for this experiment were treated in the same manner. The ensuing part of the discussion will be limited, for the most part, to the rate values since they depict passage in its entirety much more accurately than do the mean values. hean values will be discussed only inso- far as they are required as a basis for comparison with other aSpects of the experiment. Available evidence indicates a substantial amount (50;) of the total ingesta present in the reticulo—rumen after feed- ing leaves this compartment by the end of the feeding cycle (Hale, 1969; Baicn, 1958, Gray t al., 19593). According to belch (l9oc) this loss in total contents is linear except during eating. The loss of contents during meals was con- siderably greater than the loss between meals. Outflow of total ingesta from the proximal duodenum also appears to be linear except during eating. The rates of passage ranged from bad to 85L ml./lo min. for the various diets (average for all diets, 694 ml./15 min.). Passage was most rapid with the high-corn diet, less rapid but similar for the diets containing only hay and predominantly hay, and least rapid with corn 585 alone. Available evidence indicates that movements of the reticulo-omasal orifice bear a constant and characteristic relationship to motility changes of the reticulum and that transfer of ingesta through the reticulo-omasal orifice occurs at a definite stage in eacn cycle of contraction (Balch, Kelly and Heim, 1931; Stevens et al., 1960). This suggests that fac— tors whicn alter the frequency, as well as the extent to which the orifice Opens and closes, in turn will influence the flow of ingesta. Titchen (1956) has shown that stretching or preSSure on the walls of the reticulum increases the con- traction freeuency of this organ. Thus, increases in reticulo- rumen volume due to eating, drinking and salivation may accel- erate passage by increasing forestomach motility. It seems reasonable to assume that the physical nature of the food also would be important. Hay, by reason of its large volume per unit weight, logically might be eXpected to increase pas- sage to a greater extent than grain. On the other hand, hay is mechanically retarded in its passage until it becomes finely comminuted. Grain, due to its finer consistency and greater density, might be eXpected to accelerate passage to a greater extent than hay. Evidence that hay does not increase the rate of passage of in esta from the reticulo—rumen to as great an extent after eating as concentrates has been presented by belch (less) and Paloheimo and hakela (less). If, in fact, both hay and grain exert an effect separately, one might Specu- late that their effect, when fed in combination, would be 586 additive. Thus, it is not at all surprising that the passage of ingesta with the mixed diets was more rapid than for hay or corn alone. (Passage of total ingesta with the high-hay, low-corn diet was slightly less than for hay alone, but the passage of solids was more rapid.) horeover, the data indi— O (‘3 C} (D that only a low level of hay, such as that contained in 3;, was sufficient to elicit the response. Further evidence of the dietary influence on rate of passage is seen in the fact that increasing the frequency of feeding decreased the rates of passage in every case. This effect has also been shown by halcn (l9o9) for ingesta leaving the reticulo—rumen. There is general agreement that the larger particles in the reticulo—rumen a a mechanically prevented from passing to the omasum while the finely divided ones are not. Therefore, the chances of any given particle leaving the reticulo—rumen are increased by the reduction of particle size achieved dur- ing chewing. Gordon (1958a) found that the passage of hay from the rumen was greatest during rumination. Phillipson (1952a) originally thought flow from the duodenum of sheep ma more continuous during rumination; however, a subsequent study indicated this was not the case (Hogan and Phillipson, 195 ). Balcn (1959) found, by studying a wide variety of diets fed to cattle, that emptying of the reticulo—rumen was almost always more rapid during eating than between meals. The re— sults obtained in the present study corroborate this fact and also agree with the findings of HOgah and Phillipson (1960) regarding the effect of rumination on passage. Passage of total ingesta from the upper gut during eating (mean, 890 ml./lb min.) was considerably more rapid than during rumination (mean, 699 m1./15 min.) or quiescence (mean, 709 m1./15 min.). That passage during eating is influenced by the quantity of food consumed (and hence by the volume of Contents in the reticulo—rumen) is suggested by the fact pas- D ( sage was more rapid when the total ration was fed once a day (mean, 940 ml./lb min.) than when it was divided and fed in smaller amounts twice a day (mean, 8L4 ml./15 min.). Available evidence indicates that ingesta continuously passes from the reticulo-rumen throughout the day. It seems reasonable to expect, therefore, that the volume of contents in the reticulo-rumen, as well as its effect on passage, will progressively decrease after feeding. This was indeed the case in the present experiment. The rate of decline of in- gesta for the various diets (excluding Rel) ranged from -1 to -o ml./1b min. (mean, -6 ml./15 min.). The influence of the Quantity of food consumed on passage again is seen in the difference in rates of decline between frequencies of feeding. The mean rate of decline for the rations fed once a day was -4.5 ml./lb min. When the rations were fed twice daily the mean rate of decline was —e ml./l5 min. This means that the rate of passage at the end of the collections with 1x-feeding was approximately 50 percent of its initial rate whereas with 588 cx-feeding it was about 75 percent of its initial rate. Theoretically, unner conditions in whica the contents leaving the rumen are continuously replaced by food, water and saliva, one might speculate that passage would remain rather constant. The mean dry matter content of in esta entering the duodenum with the various diets ranged from 5.: to 4.1; (aver- age for all diets, 6.6;). Considerable fluctuation in dry matter Content was Observed with each diet, and the extent of these fluctuations appears to be similar to those reported \ 1 _n and Phillipson (1960, for sheep. The solids content m 0; dog patterns appeared to follow a course independent of flow (volume) but characteristic of diet. A temporary rise in the dry matter content of in esta leaving the abomasum during eating (morning meal) was observed with the high-hay and all—hay diets but not with the high—corn and all-corn diets. However, the patterns Obtained with all of toe diets were characterized by a rise in dry matter content which began soon after the morning meal and r;ached a maximum between 8—14 hr. after feeding; maximums were reached somewhat earlier for the diets containing corn than for hay alone. Tie single rise in concentration with the high—corn diets correSponded in time to the second rise ocserved with the high—hay diets, and both appsared to be related in time to the afternoon feeding. However, the fact that txis rise occurred when the animal was fed only in the morning suggests factors other than eating were involved. It is entirely possible, in View of 589 the stratification of ingesta which takes place in the reticulo—rumen (Smith g3 gl., 1956), that the water consumed immediately after the first feed was not wholly mixed with the ingesta and was rapidly passed from the rumen. As a re— sult, a temporary dilution of the ingesta leaving the rumen occurred. That this effect was not observed with the high- grain diets may have been due to the less concentrated intake of water immediately after eating, the more rapid distribu- tion of water throughout the rumen mass and the corn being found primarily in the bottom strata of the rumen. more frequent feedings of the diets did not eliminate the diurnal variations in dry matter concentration of the in- gesta but it did have a leveling-out effect on these varia— tions. Balch (1958) found, with steers receiving only one meal daily, that the ingesta lying in the region of the reticulo- onasal orifice snowed very little change in dry matter content throughout the L4 hours except for a temporary rise after eating had begun and before the animals drank. If Balch‘s findings apply in the present experiment, then it seems logi-i cal to conclude the changes in dry matter concentration were due to the amount of gastric secretions added to the ingesta at different times during the day. The constancy of p? of the ingesta throughout the day, however, suggests that gastric juice was added in relatively constant prOportion to the volume of ingesta entering the abomasum. Thus, variation in the dry matter content of ingesta leaving the abomasum must be due primarily to the variation in the solids content of ingesta leaving the reticulo-rumen and omasum. The concentration of organic matter was a reflection of 'he dry matter cancentration and followed a similar pattern of change. The mean organic matter content of ingesta leaving the upper gut with the various diets ranged from 2.7 to 5.4% (average for all diets, 6.05). The Concentration of ash in the ingesta tended to remain more constant than that of or— ganic matter although an occasional sample of ingesta was considerably higher in asn and lower in organic matter than usual due to the passage of sand from the abomasum. Gray gt al. (lQoBa) have pointed out that it is not unusual for sand to accumulate in the abomasum of sheep, and on several occa- ‘sions in the present eXperiment the U-tube, when in place, was found to be completely plugged with sand. Though the ex- tent of inorganic addition and removal in the u per gut at Specific intervals after feeding cannot be calculated from the present data, it seems reasonable to assume these factors are involved in maintaining a relatively constant concentration of ash in the ingesta. The mean ash content of the ingesta ranged from 0.5 to 0-7a (average for all diets, 0.6a). Pro- portionately higher concentrations of ash were found in the ingesta with the all-corn and all-hay diets than with the mixed diets. The fact that the mean pH values of ingesta with the diets containing single feeds were lower than with the mixed diets is of interest and suggests a relationship between the Concentration of ash and pH. From available evidence it is apparent that two major factors are involved in regulating the passage of ingesta from the reticulo—rumen. One is the activity of the reticulo— omasal orifice, and the other is the consistency of the in- gesta present in the reticulo-rumen. Thus, a basic change in either or both of these might be expected to alter passage from the reticulo—rumen. Both of these factors, which were discussed earlier with reSpect to the passage of total in— gesta, seem to apply to the passage of solids as well. The consistency of ingesta near the reticulo-omasal orifice un— doubtedly assumes greater importance with reSpect to the pas- sage of solids than to the passage of total ingesta. With the diets used in this study 1.9—5.0 Kg. of dry matter passed from the upper gut in L4 hours. Of this, more than 15; with the high—corn diets and approximately 5; with the high-hay diets was estimated to be of endOgenous origin. Thus, the passage of dry matter of dietary origin appears to be in he range of 1.6-5.7 kg./n4 hr. If it is assumed that the average dry matter content of the secretions added to the upper gut was 1.0;, approximately 40-86 1. of secretions were added to the ingesta. This estimate is similar but somewhat higher than that computed previously for the net increase of water in this part of the gut. With sheep fed various hay diets Gray gt 5;. (1958a) found --._.. t -- “rm 59; that between 60 and 70p of the solids present in the reticulo— rumen after feeding had left the organ during the day. The animals in their experiments were given constant rations, and it was presumed that the weight of soliss leaving the rumen each day was about the same as the weight ta en in. This assumption appears to be essentialiy correct for Balch (1958) found with cows that the mean loss of dry matter from the reticulo-rumen (by absorption and by passage to the omasum) during the day was 15.7 lb. while the mean dry matter intake per day for these same cows was 16.0 lb. These results have been confirmed by nanela (1955) and by Paloheimo and hahela (1959). Balch (1956) found, with cows receiving a.variety of diets, that the rate of loss of dry matter from the reticulo- rumen during eating was two or three times as great as between meals. he concluded this was due, in part, to the accelerated Opening and closing of the reticulo-omasal orifice as a result of an increased basal pressure in the reticulo-rumen and, in part, to the temporary rise, during eating, in the dry matter content of ingesta lying near the orifice. Though this pres- sure undoubtedly centinued after the meal ended, it evidently did not influence the rate at which the reticulo-rumen emptied for the loss of dry matter subsequent to eating appeared to be linear and’not a curvilinear function of the time after feeding. It should be reiterated, however, that the dry mat- ter concentration of the ingesta leaving the reticulo-rumen 593 after feeding remained relatively constant in these studies. In the present eXperiment the dry matter co.tent of the ingesta did not remain cons*ant after feeding. As a result, the passage of dry matter with time was curvilinear although it approached linearity, particularly when the an mal was fed twice a day. The rates of passag e for dry matter ranged from L0 to L: g./lb min. for the various diets (average for all diets, ad g./lo min.). Passage was most rapid with the high- Curn diet (L8 g./15 min.) and was follo ed in order of decreas- "' ing rate by the high-nay (2? g.), all-hay (to g.) and all-corn (LO g.) diets. During eating (mean, 55 g./15 min.) the pas- sage of dry matter frOm the upper gut was considerably more rapid than during rumination (mean, L4 g./15 min.) or quies- cence (mean, b5 g./lo min.). Insofar as can be determined, these observations rre CampEPELle to t-ose reported by Balch (1955) for dry matter leaving the reticulo—rumen of cows, and - n by Scerbamov (less) and iOgan and rhillipson (1900) for dry matter leaving the upper gut of cows and sheep, reSpectively. The results lend further support to the concept that hay does not influence the rate of passage of dry matter from the reticulo-rumen ta as great an extent after eating as concen— trates (Balch, 1958; Paloheimo and hamela, 1959). It is inter- esting to note that this was not the case during eating, how- ever, for hay tended to influence the rate of passage of dry matter to a greater extent than concentrates. Both rumina- tion and more frequent feeding almost always caused some reduction in the rate of passage of dry matter. It is well nnown that dry matter in the reticulo—rumen is continuously reduced in quantity, not only by passage on down the tract but also by digestion and absorption f its end-products. Similarly, the total volume of ingesta and its influence on passage is reduced throughout the day. Under usual conditions the amount of total ingesta passed through the reticulo-omasal orifice during each cycle of concentra- tion is independent of its composition. Therefore, the domi- nant factor influencing the rate of decline of total ingesta is the reduction in total volume. The rate of decline of dry matter will depend not only upon the reduction in total volume but also on the availability of residues near the orifice during each cycle of motility. The two rates do not appear to be directly related to each other. The rates of decline of dry matter for the various diets (excluding Rel) ranged from -l.l to -c.6 g./lb min. (mean, —l.6 g./lo min.). The influence of dietary intame is reflected by the difference between rates of decline for the two frequencies of feeding. When the animal was fed only once a day the mean rate of decline was —l-8 g./lb min.; it was —l.3 g./lé min. when fed twice daily. Thus, the rate of passage of dry matter at the end of the collections with lx-feeding averaged about 47% of its initial rate whereas with Zx-feeding, it averaged abuut 55p of its initial rate. With the diets used in the present eXperiment 1.6—2.5 kg. of organic matter passed from the upper gut in 24 hours. more than low of this with the high-corn diets and about a? with the high-hay diets was estimated to be of endOgenous origin. Consequently, the passage of organic matter of diet— ary origin appears to be in the range of 1.4—L.3 kg./a4 hr. All of the endOgenous organic matter was contained in the nitrogenous and ether extractive fractions. Both nitrogenous and ether extractive materials were added to the ingesta with the high-corn diets whereas with the high-hay diets the addi- tion was limited almost entirely to ether extractive material. The addition of non-dietary nitrogen to ingesta in the pper gut has been reported by Raynaud (lQoda), Hogan (1957) and Rogerson (1958), and the addition of non-dietary ether extract has been shown by hale (1953), Chance et al. (1953) and ROgerson (lgoe). Although it cannot be precisely determined from the data at what stage during the day the organic material was added, it appears distribution was relatively uniform throughout the day and was similar for all diets. Passage of organic matter from the upper gut essentially paralleled that of dry matter, and was similarly influenced by the factors which influenced dry matter passage. The rates of passage for organic matter ranged from 17 to as g./15 min. for the various diets (aver— age for all diets, an g./15 min.). Passage was again most rapid with the high-corn diet (24 g./15 min.) and was followed in order of decreasing rate by the high-hay (b2 g.), all—hay (so g.) and all-corn (l? g.) diets. Excluding Rel, the amount of organic matter passed from the upper gut prOgress- ively declined at the rate of -l.O to —b.5 g./lo min. (mean,' -l.a g./lb min.). The reaponse of organic matter to frequency of feeding was the same as that noted for dry matter. The terminal rate of passa e averaged 47; of its initial rate g waen the total rations were fed once daily. Hhen the same rations were divided and fed in equal amounts twice daily the terminal rate averaged dd; of its initial rate. There is considerable evidence to indicate large quan- tities of ash are added to ingesta in the upper gut (Boyne . an (1) t él-: 1956; Rogerson, 195g. _... D Balch, 1958; Scerbakov, 19 ~; Hogan and Phillipson, 1960). This evidence is further sub- stantiated by the results obtained in the present study. With the high-corn diets the amount of ash added to the in- gesta from non-dietary sources exceeded the dietary intake. Considerably less, but yet a substantial amount of ash was added to ingesta with the high-hay diets. From 0.3 to 0.5 Ag. of ash passed from the upper gut per day with various diets, and of this, some 15 to 57» was apparently of non— dietary origin. This is based on the assumption that all of the dietary ash was passed from the upper gut. It is improb- able that this is actually the case, however, for the trans— fer and exchange of inorganic ions between the blood and reticulo-rumen-omasal ingesta has been demonstrated on a number of occasions. It may well be that this mechanism is of consideracle importance in providing a rather constant ionic environment in the upper gut. This particular phase of rumen physiology agpears to merit more attention than has been devoted to it thus Iar. Inorganic material passed from the upper gut at the rate of 5.0 to 4.7 g./15 min. with the various diets (average for all diets, 4.1 g./15 min.). In general, passage increased as the proportion of hay in the diet ‘ncreased, and as the dietary intahe of ash increased. However, the passage of ash was not directly related to its dietary intake because the endOpenous addition of ash to the ingesta was proportionately greater with the high-corn as compared to the high—hay diets. The reSponse of inorganic passage to eating, ruminating, quiescence and frequency of feeding appeared to be more closely related to the passage of total ingesta than the passage of solids. Passage of ash was proportionately less rapid during eating and more rapid during rumination than that of organic matter. This suggests that the inorganic fraction is more closely associated with passage of the soluble rather than the insoluble fraction of the ingesta. The rates of decline which were computed for the in— organic fraction lend further support to this point. Exclud— ing 3L1, the quantity of ash passed from the upper gut pro- gressively declined at the rate of -O.l to -O.4 g./15 min. with the various diets (mean, -O.z g./15 min.). The mean rate of decline for the rations fed once a day was ~O.3a g./15 min. 598 hhen the rations were fed twice daily the mean rate of decline was -o.l; g./lo min. This means that the terminal rate of passage with lx-feeding has about one-half of its initial rate whereas Eiti bx-feeding it was approximately 70 per cent of its initial rate. The effect of more frequent feeding was of particular interest in this study because, even when the animal was fe‘ twice daily, about 60” of the dietary ash was consumed at the morning meal. Results of the preliminary eXperiment indicated the hourly data were equally as valuable as the lo-minute data for esti- mating tne rates and trends of passage. It was also apparent that hourly sampling intervals Mere required to obtain suffi- cient sample for detailed analysis. On the other hand, the hourly data were not as precise as the lS—minute data for evaluating time-factor-passage relationships. These consider— ations appear generally to apply to the present part of the experiment as well. The passage, and factors affecting passage, of total ingesta, dry matter, organic matter and ash have been discussed previously with respect to the lé-minute data. Consequently, they need not be discussed further here except to present values for these fractions on the basis of hourly intervals for comparative purposes. The rates of passage were as fol- lows: total ingesta, a.z to 3.5 l./hr. (mean, s.e); dry matter, 74 to la: g./hr. (mean, 105); organic matter, 61 to 10L g./hr. (mean, 84); ash, 15 to L5 g./hr. (mean, b2). 599 Excluding the values for 2L1 which indicated an increase rather than a decrease in passage with time, the correspond- ing rates of decline here: total ingesta, —L to —8 ml./hr. (mean, -6); dry matter, ~l-l to -4.0 g./hr. (mean, —a.5); organic matter, -U.9 to -;.7 g./hr. (mean, _e.0); and ash, -O.L to -0.7 g./hr. (mean, -U.5). Since the quantity of soli 8 passed to the lower gut depend on the extent of addition of solids to and/or their removal frOm the ingesta in the upper gut, it seems reasonable to eXpect that passage of the residues with time might reflect the rate of di:;StiOH and absorption or addition. In this respect, passage of the individual organic components was of particular interest. Protein output from the upper gut ranged from 0.6 to 0.9 a-./n4 hr. and, relative to intake, decreased as the dietary CL L4 7. intake of protein increased. mhis resulted from the addition of non-dietary nitrogen to the ingesta with the high—corn diets whereas a net loss occurred in the upper gut with the high—hay diets. Endogenous nitro en may enter the gut via the saliva (Somers, 957), by transfer from the blood through the rumen tall (doupt, lacs, 1952), in sloughed epithelial debris (Badawy et gl., 1956a) and in gastric juice (HOgan, 195?). It is probable that some non—dietary nitrOgen was added to the ingesta nith each diet, and the observed output was a balance between the amount of non-dietary nitrogen added 400 he amount of dietary and non-dietary nitrOgen removed. Q) C" I): cf Balcn (lend) found substantially greater quantities of saliva nere secreted with hay diets than with concentrate diets. fiance, one night legically expect the amount of nitro- gen added to the ingesta Wltfl hay diets to be greater than kiln concentrate diets. On the other hand, Houpt (1963, 1959, indicated that the transfer of urea from the blood to the in- gesta through the rumen hall may be an even more important S:UPC& or endogenous nitrogen than saliva, particularly with high—energy, nitrogen-poor diets. The ability of ruminants on low-nitrogen diets to conserve nitrOgen by decreasing the excretion of urea via the hidneys and by recycling it through the reticulo-rumen has been demonstrated by Schmidt-Nielsen g" gi. (1857) and Houpt (lQoEL. Evidence that losses of nitrOgen from the upper gut nit- high-nitrogen intakes are Considerably more entensive than those with low-nitrOgen in- 1 tanes has been obtained by Belch (1957) 8L0 by Gray 93 al- .r (1908b). There also is a substantial amount of evidence which indicates the quality or source of protein is an important factor governing the net gain or loss of nitrOgen in the upper gut (ncbonald, 190a, lgoe; Chalmers t al., 1954; Chalmers and Synge, lgbea, 19o4b; Annison gt al., 9S4; Gray and Pilgrim, (C) lace; ncDonald and Hall, 1957; BFlCh: l (D 57; Gray at 5;., (C 1 can). nore soluble proteins appear to be rapidly degraded with resultant large losses of nitrOgen as ammonia whereas less Soluble proteins apparently are not. Zein, the protein 401 of corn, is particularly nOteworthy in this regard by reason of its relatively slow rate of hydrolysis compared to other proteins in the reticulo-rumen (ncConald, 195;, che). The importance of dietary starch in the utilization of both dietary and non-dietary nitrogen is well known (Annison and Lewis, lQoe). The foregoing relationships seem to be borne out in the present experiment. The losses of dietary nitro en witd the high-corn diets were apparently not extensive and did not exceed the addition of nitroten from non—dietary sources. On the other hand, the losses of dietary nitropen with the high-hay diets actually may have been considerably greater than the data indicate. The rates of passage of protein, whico ranged from 25 to 57 g./hr. (average for all diets, 50 g./hr.), were highest for the high-corn diet, lower and similar for the high—hay and all-hay diets and lowest for corn alone. In view of the levels of protein intaae with the various diets, the similar— ity between rates of passage were unexpected. however, this can be readily accounted for if the added nitrogen is con— sidered on one hand and the net loss of nitrogen is considered on the other. Protein output from the duodenum declined with time for all diets except Rel. The rates of decline varied from -o.a to -0.7 g./hr. (mean, -O.5 g./hr.) and, in general, did not differ greatly between diets for a given frequency of feeding. The decline was less rapid when the diets were fed twice 402 daily. Relative to the rates of decline of the other organic components, the rate of decline of protein was less rapid. Thus, passage of protein was not as rapid initially as the Other components but was more rapid during the terminal stages of ’he feeding cycle. The terminal rate of passage averaged about 68a of its initial rate. It was found with each diet that the protein content of the ingesta leaving the upper gut was hi her than that of the food ing ated and pregressively increased during the day. Undo btedly the removal of carbo- hydrate in the upper gut accounted for this in part, however, tie addition of non-dietary nitro en during the day must have contributed also. At what stage(s) during the feeding cycle nitrOgen was added to the ingesta is Open to apecu ation. Though the transfer of urea from the blood to ingesta through the rumen wall may assume considerable importance under cer- tain conditions, the major source of non-dietary nitrOgen in most instances is probably saliva. The secretion of saliva in ruminants is known to be continuous. Salivary output is appreciably increased above resting secretion during eating (mendel, 1960) and during rumination (Benton, 1957; Stewart and Dougherty, lgba). If it can be assumed that the nitrogen content of the saliva was not markedly influenced by these stimuli in the present experiment, then one might lOgically exPect a greater addition of non-dietary nitrOgen during rumination than during eating since considerably more time was devoted to rumination. It also follows that, due to the 405 distribution of the periods of rumination, more endogenous nitrOgen would be added during the latter part of the cycle. This concept does not necessarily hold for the all-corn diet, for there was no rumination Witfl this diet. However, it should be pointed out that the decline in passage of protein for this diet was proportionately more rapid than for the other diets. lflls suggests the addition of non-dietary nitrOgen to the ingesta was greatest during the early part of the feeding cycle. The total output of ether extract from the upper gut ranged from 1&5 to 458 g./b4 hr. and, in each case, was more than the amount consumed in the correSponding diet. Thus, a substantial Quantity of non-dietary ether extract was added to the ingesta with each diet. This has been confirmed by (O a number of studies (Hale gt a ., 1 47b; Chance at al., 1955; Rogerson, 1955). There appears to be little agreement as to the origin of this non-dietary material, however. According to Hale at gl. (1947b) this addition was due to the synthesis of fats by the rumen micro-organisms. On the other hand, Garton and Oxford (1955) were unable to show synthesis of polyethanoid 018 fatty aci s by rumen bacteria of sheep fed on nay. decent evidence presented by Habel (19:9) sug- gests these non—dietary ether extractible materials may be triglycerides derived from epithelial desquamation. Passage of ether extract from the upper gut was most rapid with the high—corn diet, less rapid with the high-hay 404 and all-hay diets, reapectively, and least rapid with corn alone. Frequency of feeding had no appreciable influence on ether extract passage. The rates of passage ranged from 6.0 to 10.? g./hr. (average for all diets, 5.1 g./hr.). With the exception of the rate for corn alone, the rates of passage of ether extract appeared to be related to the dietary intake. lfllS infers that the addition of non—dietary ether extract to the ingesta was also related to the dietary intake. Whether these relationsnips actually exist or not cannot be determined from the present data because it is not precisely known what part of the ether extract in the ingesta was of dietary origin and what part was of non-dietary origin. The output of ether extract, like that of protein, de— clined with time after feeding for all diets except Rzl. The rates of decline varied from -o.oe to -O.5c g./hr. (mean, —b.l7 g./hr.) and, in general, were much more rapid for the high—corn diets than for the high-hay diets. Relative to the decline of the other organic components, the decline in passage of ether extract was slightly more rapid than that of protein, particularly with the high-corn diets. However, the decline was considerably less rapid than that of crude fiber and h-free extract. Tiis indicates the passage of ether ex— tract was relatively less rapid initially but more rapid dur- ing the latter stages of the feeding cycle than passage of the carbohydrate fractions. The terminal rate of passage was about 62A of its initial rate. In the ingesta leaving the 405 upper iut the concentration of ether extract was substantially greater than that in tie food and remained relatively constant throughout the feeding cycle. Loss of carbohydrate in the upper gut probably was involved to some extent, as was the addition of non-dietary ether extract. lhe nature and time of addition of non-dietary ether extract to, and the extent of hydrolysis and removal of dietary ether extract from in- gesta in the upper gut is indeterminable from the present data. lhus, any discussion of factors influencing the decline in passage of ether extract is somewhat conjectural. If it is assumed that most of the non-dietary ether extract is de- rived from epithelial desquamation, one might logically ex- peot the extent of addition to be greatest with the more scabercus, nigh—hay diets. horeover, the addition would be eXpected to occur prinarily during the early part of the feed— ing cycle before the hay became well soaked and nacerated. It is also probable that the ether extractible substances in hay are less susceptible to hydrolysis in the upper gut than those in corn, particularly during the early part of the feed- ing cycle. On the other hand, if it is assumed that most of the non—dietary ether extract is a result of synthesis, then one night expect the addition to the ingesta to be greatest with the high—corn diets and to occur some hat later in the feeding cycle. Furthermore, the ether extractible substances in corn are more susceptible to hydrolysis than those in hay, and hydrolysis would be expected to occur in the early part of 406 the cycle. Providing these assumptions are reasonably valid, one night conclude epithelial desquamation is not a major source of endogenous ether extract in the upper gut, synthesis of ether extractible substances does occur after feeding, partlcularl; with the high—corn diets, and hydrolysis of ether extractible substances occurs in the early part of the cycle tith the high-corn diets and in the latter part with the high— nay diets. It Should be pointed out in regard to the last conclusion, however, that there is no evidence to indicate the end—procucts of lipid hydrolysis are absorbed from the upper gut unless hydrolysis proceeds to the short—chain fatty acids. Until conlirnation by independent nethods are obtained these conclusions must be regarded as very tentative. It was previously indicated that the passage of both protein and ether extract was complicated by the addition of non-dietary substances to the ingesta. Crude fiber and N-free extract are not subject to endogenous addition and thus, pas- sage of these fractions throuth the upper gut should be indicative of the extent of their renoval in that segment of the tract. lne output of crude fiber from the upper gut ranfled frOm 7b to 448 g. in :4 hours and, in general, increased as the dietary intahe of hay increased. However, relative to intake, the output of crude fiber decreased as the dietary intaae of hay increaSed. fhus, it was quite apparent that in- creasing the proportion of corn in the diet sharply depressed the removal of crude fiber in the upper gut, an effect which 407 has been demonstrated in a number of other eXptriments (Head, lgdd; belch, 1937; Rogerson, 1938). ihe rates of passage of crude fiber varied from 3 to la g./nr. (average for all diets, ld g./hr.). The rate for Corn alone, nhicn was substantially loner than those for the other diets, was expected due to the markedly lower level of fiber intale. hith the other diets, the rate of passage in— L" creased as the ietary intahe of fiber increased. However, the relationShip between dietary intaxe and rate of passage use not a direct one because of the depressing effect in— creased amounts of corn had on fiber renoval in the upper gut. These findings are in good agreenent with those obtained by Ealoheino and nanela (lgoe). It was indicated previously that a decline in passage of the other fractions of ingesta wit; time after feeding occurred for all diets except Rel. P988856 of the crude fiber fraction was no exception. ine rates of deCiine for this fraction ranged fron —O.l to —U.7 g./nr. (nean, —O.4 g./hr.) and, when the animal was fed only in the morning, increased as the dietary intaae of fiber increased. These rates reflected the very rapid passage of the fiber fraction during the initial two hours after feeding. This effect was not as noticeable when the daily ration was divided and fed in two equal feed— inis. Relative to the rates of decline of the other organic couponents, the deCline in passage of crude fiber from the upper gut has considerably more rapid in each case than that 408 of prm>tein and of ether extract. On the other hand, the deciixie tended to be less rapid with the high-corn diets but none rawid with the high-hay diets than that of N—free ex- tract. lnis infers crude fiber was passed less rapidly dur- ing tgie initial part of the feeding cycle and more rapidly durirqi the latter part than fi-free extrac when corn was the mayor“ consonant of the diet. The trend appeared to be re— verseCi‘nitd the high-hay diets. It is probable that several factgxrs cuntributed to this difference between diets. Avail- able evidence indicates the carbohydrates of corn are more susceiutible to dearadation than tqose of hay. Consequently, tn:;ireferentiai feraentation of the carbohydrates of corn wuuld. tend to r (I‘ tard the breandown of the fibrous carbohydrates 0f 3837 until later in the feeding cycle. There was also less ruminaation wit; the nigh—c;rn diet, thus reducing to same ex- tent TLue possibility of a ra;id reduction in particle size of theliay contained in the diet. In addition, the corn in the diets was finely divided and nore dense. Zhis would contribute t9 its earlier and more rapid passage from the reticulo—rumen ‘tumiiiay wniCh, in the long state, is mecnanically retarded until finely comminuted. -A further point of interest with respect to passage of tfie<3rude fiber fraction was the difference between crude five? concentrations of the ingesta wit; the high-corn versus tfle.hiEh-hay diets. There was a progressive decrease in the cpufle fiber cantent of the ingesta wits each diet, thus indi- 409 eating crude fiber was renoved from the upper gut after feed- ing. however, the loss of crude fiber with the high-corn diets atoeared to be overshadowed by the extensive loss of n-free extract bot; by passage to the loser gut and by diges— tion and absorption in the upper gut. As a result, the con— oh—corn centration of crude fiber in the ingesta with the hiC diets was in each case greater than that in tie correSponding diet whereas nitn the high-hay diets the concentration was less. Of the various organic fractions studied K—free extract was quantitatively the most important not only with reapect to the dietary intaae but also with reapect to the activities of the reticulo-runen. Consequently, sone of the differences in passage of this fraction between diets were expected. On the other hand, a number of differences were somewhat unexpect— ed in View of the results reported by Balch (1957). With the diets fed in the present eXperinent, the output of N—free extract in ingesta from the upper gut varied from 0.0 to 1.0 at. in 44 hours. Substantially less K—free extract was passed with the all-corn diet than with the diets containing hay. nits these diets the output of N-free extract decreased as the dietary intane of k-free extract decreased. However, on the basis of intaie preportionately more R—free extract was passed frOn the upper gut as the dietary intake decreased. This infers that, as the ratio of corn to hay in the diet in- creased, larger amounts of corn escaped fermentation in the 410 upper gut by passing to the lower gut, and the K-free extract of lay was less digestible than that of corn. lhe rates of passage of K-free extract ranged from 24 to so g./hr. for the various diets (average for all diets, 33 g./hr.). Passage was eansiderably more rapid with the high- corn diet (45 g./hr.) and was followed in order of decreasing rate by the high—hay (53 g.), all—hay (b9 g.) and all-corn (a4 g.) diets. Although little has been done with reapect to the passe e of ingesta with diets as extreme as corn alone, (7" muCh of the available evidence suggests motility of the reticu— lo-runen is rather phlegmatic with diets of this type, and hence passage is sonewhat sluggiSh in nature. With diets containing some hay in addition to concentrates, however, there is good evidence that the passage of concentrates from the reticulo-ruhen is accelerated (sales, 1907; Paloheimo and hanela, lgtg). both belch at al. (19a4) and Blaxter at al. (lane) have stressed that the amount of hay in the diet is a najor factor influencing rumen motility, and thus the tine residues remain in the reticulo—runen. The fact that feeding hay and ground corn in combination resulted in con- siderably more rapid passage of K—free extract than feeding either one singly lends support to the validity of these effects. A more detailed discussion of this particular aSpect of passage was presented earlier with respect to the passage of total ingesta. 411 Data presented by Balch (1955) indicates passage was neat rapid during eating and declined thereafter until the next neal. This was particularly true with diets rich in concentrates, the highest rates occurring early in the meal. he preposed that the accelerated passage during eatin :ss, UQ (4 q in part, the result of a temporary rise, during eating, in the dry hatter content of ingesta lying near the reticulo— omasal orifice and, in part, the result of increased motility of the reticulo-runen. In general, the results of the present experiment are in good agreement with these findings. An in— crease in the E-free extract concentration of the ingesta after the morning meal was observed with all of the diets except those containing only hay. These increases, which varied in their degree of transience, appeared to be related to the anount of corn in the diet; the increases with the high-corn diets were less transient in nature. The ingesta with eacn diet contained considerably less l—free extract than was contained in the diet, indicating extensive removal of this fraction in the upper gut. The average concentration of K-free extract with both of the mixed diets was higher than with nay or corn alone. The decline in passage with time after feeding, which was seen for the other organic components with each diet except Rel, also was observed for K-free extract. The rates of decline ranged from -O.5 to -l.s g./hr. (mean, -O.9 g./ hr.). with the mixed diets the decline in passage was con- 41b siderably more rapid than with corn or hay alone. This sug- gests undigested corn was rapidly passed from the reticulo— rumen during eating, and rapid fermentation of the corn re- naining in the upper gut progressively reduced the amount passed with time after feeding. The decline in passage of L-free extract, relative to the decline in passage of pro- tein and ether extract, was considerably more rapid in each case. HoweVer, relative to the decline in passage of crude fiber, it was more rapid only with the high—corn diets. It seems reasonable to assume, therefore, that the ratio of hay to corn was an exceedingly important factor in determining whether the corn was fermented for the most part in the upper gut (reticulo—rumen) or whether it was rapidly passed to and degraded in the lower gut. A clearer estimate of this effect would be Obtained by combining he method used by Balch (1957) with that used in the present study. Summary A re-entrant duodenal fistula, surgically established in a Holstein steer, was employed to determine the feasability of making total collections of ingesta from the duodenum over a 00mplete feeding cycle, to partition digestion in the upper gut from that in the lower gut and to study the effect of physical maheup of the diet on the passage of ingesta through *1 the upper gut. our different diets consisting of varying hayzcorn ratios were fed at constant intake (10 lb./day) 415 51‘ either once or twice daily. The diets were 100% corn, 70» corn-50fi~nay, 70w hay-50% corn and 100% hay. Total digestion was determined by the ratio tecnnique using chromic oxide as a narner. Digestion in and passage froa the upper gut was determined by total collection of ingesta passing from the proximal duo enum over a Lé—hour period; the 'continuous' nethod of collection and re-introduction was employed. Ligestion in the lower gut was determined by difference. whether or not the values Obtained by this method are accu— rate estimates depends upon the validity of the original premises upon wnicn the method was based. The range or digestibility of dry matter in the unper gut was iron Lt-Cbp and in the lower gut from Ld-48fi. On the average on” of tle'total digestion of dry matter occurred in “C C pper gut. Corrected for the endogenous protein, ether Cf extract and ash which were added to the ingesta, the losses of dry matter in the upper gut ranged from as—::; and averaged 67% of the total digestion. PrOportionately less of the dry matter was digested in the upper gut with the mixed diets than with corn or hay alone. The range of digestibility of dry matter whicn entered the lower gut was from 4L-64i. From d4-65m of the organic matter consumed nas renoved in the upper gut and an additional ld—SQH disappeared in the lower gut. Losses in the u_per gut were due almost entirely t; remo al of the carbohydrate fractions; BJOSS in the lower .1 gut were largely due to tne removal of protein and ether 414 extract. With the diets CLhtElnlng primarily corn G15% crude protein), there was evi- dence of a loss of dietary nitrogen (d-ldi). These results suggest the level and source of dietary nitrogen, as well as 4— ne dietary carbohydrate, are intimately involved in deter— mining tne net loss or gain of nitrogen in the upper gut. 0n the average, aggroximately 70% of the nitrogen entering the lower gut has digested and absorbed. A substantial amount of ether extractible material of non—dietary origin :as added to ingesta in the upper gut with each diet, thus indicating there was no digestion of this fraction in the upper gut. The removal of ether extract in the lower gut accounted for the total digested in every case. Digestibility values for crude fiber indicate all of the digestion of this fraction took place in the upper gut. In- creased amounts of corn in the diet depressed crude fiber digestion. The negative digestion coefficients for the crude fiber residues entering the lower gut suggest this fraction accumulates to a certain extent at some point in the lower gut. The digestion of K—free extract in the upper gut varied from 59-8;%, and accounted for more than 75% of the total. An additional a-Zlfi-was removed in the lower gut. PrOpor— 415 tionately less k-free extract was digested in the upper gut and prOportionately more was digested in the lower gut with the mixed diets than with carn or hay alone. This suggests undigested corn escaped fermentation in the upper gut by rapidly passing from the reticulo-rumen; it was subseQuently digested in the lower gut. The importance of the upper gut in carbohydrate degradation, however, is clearly evident. negative digestion coefficients were Obtained in every case for asn in the upper gut, thus indicating a considerable addition of non-dietary inorganic material. The amounts added to the ingesta ranged from LOz-deé g./day, and in some in— stances exceeded the dietary intaxe. The amount of ash re— moved in the lower gut always exceeded the dietary intake. Flow of ingesta from the upper gut was essentially con— tinuous irreSpective of diet. The 'continuous' method of collection resulted in irregular but frequent passage of in- gesta from the upper gut. Flow was accelerated when ingesta was not returned to the lower gut, and was reduced for a period of time when ingesta was re-introduced. The duration of this effect appeared to be related to the quantity of in— gesta re—introduced. Results obtained in one instance (R21) suggest that frothy ingesta may inhibit passage from the upper gut by producing distention of the small intestine. The pH of ingesta passing to the duodenum fluctuated only within narrow limits; it was not influenced appreciably by diet or frequency of feeding. 416 From :5-ao liters of ingesta passed from the upper gut in L4 hours. It was estimated that a net increase of 68-54 liters of water occurred in the gut between the mouth and the proximal duodenum. Saliva and gastric Juice probably account- ed for most of this increase. motal ingesta passed from the upper gut at the rate of bed-85c ml./15 min. Passage was more rapid with the mixed diets than with corn or hay alone. During eating passage was accelerated. This effect was greatest when the total ration was fed once a day. The amount of ingesta passed from the upper gut progressively decreased at the rate of —l to -b ml./lo min. with time after feeding. more frequent feed- ing resulted in less rapid rates of decline. The mean concentration of dry matter, organic matter and asn in ingesta leaving the upper gut with the various diets was 5.6, 5.0 and 0.6;, respectively. The concentration of solids with each diet increased soon after the morning meal and reached a maximum between 8—14 hr. after feeding. with the high-hay diets the concentration of solids also exhibited a temporary rise during eating. The concentration of organic matter followed a pattern of change similar to that of dry matter. The concentration of ash tended to remain more con— stant. Of the total dry matter (1.9—5.0 kg.) passed frOm the upper gut in L4 hr., about ldfl with the high-corn diets and about hp with the high-hay diets was estimated to be of non— 5‘“. h -.‘-N <\ «E J l e S ;. d 5‘ he 0... n A. : § Eu. nC e .s x a: § U 1r. 417 dietary origin. The rate of dry matter passage was 20-29 g./ lo min. Passage was most rapid with the high—corn diet and was followed in order of decreasing rate by the high-hay, all- nay and all-corn diets. Dry matter passage was accelerated during eating and was influenced to a greater ex ent by hay during this period than by the corn. Rumination and more frequent feeding usually reduced the rate of dry matter pas- sage. The amount of dry matter passed from the upper gut with time after feeding decreased at the rate of -l.l to -a.5 g./ in min. Thus, the terminal rate of passage was about 50% of its initial rate. About 10» of the total organic matter (1.6-z.5 kg.) passed from the upper gut in as hr. with the high-corn diets and about 2% with the high-hay diets was estimated to be of endogenous origin. The rates of passage with the various diets ranged from 17-45 g./15 min., and the amount passed after feeding decreased at the rate of —l.0 to -L.3 g./15 min. The passage of organic matter reacted similarly to that of dry matter. SOme 15-b7w of the total ash (0.3—0.5 kg.) passed from the upper gut per day was apparently of non-dietary origin. with the high—corn diets the amount of non—dietary ash ex— ceeded the dietary intake of ash. Ash passed from the upper gut at the rate of 3.0-4.7 g./15 min. Its rate of decrease with time after feeding varied from —O.l to —0.4 g./lo min. -w The passage of ash appeared to be more closely associated with -.\ f- s c s V . I . 4 . r\ 31‘ fi . ¢ ‘ . ‘ \.\ F rC : A . . F; r u v .l . k .n . BC 4. K i L .CW 8’ hi ; U r»; C» .. N . ¢ 3 5 u . . i 4 i L. _C E ... .J a; g L . . _wc M. ..i S E d S ._ u i; C S .7. c. 5 .C . v . r V... 2.. ... i wt! 2.. _ u a c .. . is. H .t a: .. n C. h. , .. : h; ., u .A t o .. . . u .I rm. .9 {U Ad ..0, 2. .. . .N‘ .f :J. ..u I; .u ah ru ~ . v .. u . \ x . 1» z e .. ¢ 418 passage of the soluble rather tian the insoluble fraction of the ingesta. :rotein output from the upper gut varied from 0.6 to 0.9 Aé./L4 nr. A net gain in protein due to non-dietary E was ooserv:d MitJ the high-curn diets whereas a net loss occurred with the high-hay diets. Protein passed from the upper gut at the rate of L5-67 g./hr. The rate of decrease after feed— ing varied from —O.c to -O.7 g./hr. Relative to the rates of decline for the other organic fractions, the rate for protein was least rapid; the terminal rate of passage was 68% of its initial rate. The protein content of ingesta leaving the upper gut was higher than that of the food ingested and pro— gressively increased during the day. lfle output of ether extract (145-L53 g./54 hr.) from the upper gut was more than the amount consumed in the corre- Sponding diet. The rates of passage varied from 6.0-10.7 g./ hr. It was estimated from the rates of decline (-o.os to -O.dc g./hr.) that the terminal rate of passage was about 62% of its initial rate. Relative to the other organic compo— nents, the decrease in passage of ether extract was slightly more rapid than that of protein but considerably less rapid than that of the carbohydrate fractions. The ether extract Content of ingesta leaving the upper gut was greater than that in the food and remained relatively constant throughout the feeding cycle. From 75-448 g. of crude fiber passed from the upper gut «Le 419 per day. Relative to intane, the output of crude fiber de— creased as the dietary intake increased. Thus, the removal of crude fiber in the upper gut was sharply depressed by in- creasing the preportion of corn in the diet. Crude fiber passage varied from 5—19 g./hr. The decrease in passage of crude fiber (-o.l to -o.7 g./hr.) after feeding was relatively more rapid than that of protein and ether extract and, with the high—hay diets, L—free extract. It was less rapid than that of L—free extract with the nigh-corn diets. 'he crude fiber content of the ingesta with the high-corn diets was greater than that in the corresponding diets whereas with tne high-hay diets the concentration was less. There was a progressive reduction in crude fiber content of the ingesta after feeding each diet.- titrogen—free extract output from the upper gut varied frOm eta-1.0 Ag. in L4 hr. The rates of passage ranged from 244%3g./hr. for the various diets. Feeding hay and corn in coaoination resulted in consideraely more rapid passage of E-free extract than feeding either one singly. A transient increase in the R-free extract cantent of the ingesta after tne morning meal was observed with all of the diets contain- ing Corn; the increases appeared to be less transient with the nigh—corn diets. The concentration of K—free extract in the ingesta was subatantially lower in each case than in the corresponding diet. The decrease in passage of N—free extract (-b.é to -l.9 g./hr.) after feeding was considerably more any a. A .. v t.“ ”-v w E . u v v. t a\» 4:0 rapid with the mixed diets than Jith corn or hay alone. This decrease was relatively more rapid than that of protein and ether extract with eacn diet and crude fiber with the high- corn diets. The results suggest that (l) a variable amount 3 of corn miy escape fernentation in the reticulo-rumen by q rapidly passing to the lower gut and (z) the hayzcorn ratio is an inportant factor in determining the extent to which this will occur. PhysiOlOgically, the aninal appeared to be undisturbed by the long—time collection procedure for the values obtained for various activities suc; as eating, rumination, etc. were comparable to those reported in the literature. It is emphasized that the data obtained in this experiment involved the use of only one animal without repetition of treatment. Thus, the results must be regarded as tentative until con- firmed either by this method or by independent methods. The results do indicate, however, that the method is a feasible means of partitioning digestion in and studying passage of ingesta through the gut. x7. 7 a. ..L [T ‘ 4C1 LITERATURE CITED Alexander, F. A review of knowledge available concerning 19o4 digestion in domestic herbivore. Brit. Vet. J., 110: 146-1oe; 136-e04. Allen, a. 5. Personal communication. 86b Alvarez, a. C. An Intrgdpgtion t9 Gastro—enteroloav. 5rd Ed. 1840 Paul B. doeber, lnc., Lew York. Amadon, R. h. 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L., thsteit, G- on 1941 Preliminary OUSBPV€tiOLS on chemic . . rumen in;e esta with and without urea. J. 3 L4: £31-00. ‘ f‘ heiss, 1. E. Ihysiolo ical studi: s on eructation in rumi- 1965 nants. Onderstepoort J. Vet. Res., 26: 461—185. ”elier, R. A. The amino—acid C5nposition of 1ydrolyzate of 1967 uicrOLial preparations from tie runeh of sheep. Austral. J. Biol. Sci., 10: 584 -5;9. ,L 0) L0 Lelle , R. A. and F. V. Grey. [he pesse;e of stercl through 9:4 the stoLech of the shuep. J. 3x;. 8101., 31:40-48. Leller, R. A., Grey, F. V. end L. F. Pil~riz The conversion 1908 3“ giant hiCFOieL to microoiel nitro_~n 1n the rumen 1 of the sheep. grit. J. Lutrition, 12: 4zl-4z9. LG i. lzsr. 1he eLylese of Clostridium 'cuL. EiocheL. J., 48; 415-4;3. e on the di estive process of sheep. (trens— title) J. Lenoxirtocioft £7: 177—L49. Lilley, L. 5., RiL-s, J. L., Coley, %. W., Butler, C. D. lacL Jr. sLd A. fieiser. 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The uechrrisL of cellulose 13;; digestion in the ruminsnt oreriSL. TIT. The transforLetlon of cellulose into glucose by the agency of cellulose-snlittiLg tecterie. J. Agr 501-, 18: 715-7L5. Young, 3. E. A d ofeLel fistula in the LoviLe eniLel for 1951 ex eriL.ental investigstioL. J. AL. Vet. Led. ASSL., 118: 98—100. 470 APPENDIX Iaole 18. Influence of no re-iLtroduction on pi and composition of ingest? peeeeo from duodenum ‘1 u‘ one volume, A: lilae A—Jtlrl 0 '0 p1: Organic metter A J' :31 P5 H (‘3 D" H (O O H De L3 (O O) T" HHD' NI—Jb' r—J r—J ((7 r—J (1) (2) (IN ((1 (:3 @«wn-o: (nouown O {O (O (O n+AFJH quw FFJFJH 0(D«)© C‘ (51 vb (D H H +—’ H (0 \‘1 (D (C O (0 Co. (I) (‘3‘) +¥> 01 (n (II-1 $cn C‘: FPPPPPCN b.80 4.0L rh-unbhb- (\‘flmto hWDLOD“ wwwm ".0101 OHCA+¥> Ch (‘ 0.92 5.80 0.80 (:1 0 7'3 3.77 0.78 0.31 “.87 C‘.‘ | 1 line Inif.- ..-—- :45 DJ |'—’ O") U? C‘ 0‘ 47b Influence of no re—introduction on the volume, pd and conposition of ingesta passed from tne duodenum Dry Orgsnic Volume matter matter Ash 475 1.80 3.05 8.33 0.75 9L5 p.05 3.68 b.90 0.70 940 8.1: 3.74 8.89 0.8r nr. 785 L.b8 4.09 3.18 .91 430 L.Lb 4.48 3.55 0.98 140 4.00 3.91 3.08 0.85 590 n.80 3.80 3.09 0.71 hr. 490 (.07 4.04 3.15 0.90 4L0 L.Ob 4.09 3.L4 0.87 95 b.b4 4.85 3.34 0.91 330 L.lO 3.35 2.50 0.85 nr. 7L0 8.09 3.51 b.81 0.80 440 L008 3.65 8.80 0.84 5L0 4.05 3.57 4.74 0.83 685 8.4 3.93 3.01 0.93 nr. 630 4.89 3.88 5.89 0.79 465 .9C 3.37 8.64 0.74 440 8.06 3.L3 4.45 0.78 645 (.10 3.63 6.87 0.75 nr. 640 8.15 3.84 3.00 0.82 L75 b.b5 3.35 2.54 0.83 500 b.10 3.L3 8.48 0.77 535 b-lé 3.36 8.55 0.78 hr. 540 c.15 5.53 8.77 0.75 Iecle 8a. 473 Influence of 15—minute re—introduction on the volume, pH and CuRpOSltion of ingesta pessed from the duodenum ..‘“ ..'—“..‘.— Dry Organic Tine Volune matte matter Ash min. ml. pH 8 8 fl 5 530 3.34 4.59 3.89 0.70 30 1140 1.83 3.98 3.85 3.67 45 950 1.78 4.14 3.44 0.73 1 nr 1310 1.80 4.46 5.71 0.73 15 1850 8.81 5.50 4.66 0.84 50 670 1.70 4.59 3.77 0.88 45 1800 8.08 5.81 4.38 0.89 8 nr. 780 1.64 3.50 8.91 0.59 15 140 1.90 3.30 8.58 0.78 30 60 8.50 8.50 8.08 0.48 45 860 1.48 8.60 1.94 0.67 3 nr. 1108 1.55 8.77 8.87 0.50 5 900 1.71 8.86 8.48 0.44 30 745 1.78 3.57 8.97 0.60 45 680 1.70 4.85 3.47 0.78 4 hr. 750 1.78 4.01 3.87 0.74 15 895 1.98 3.88 8.99 0.83 30 300 1.96 8.78 8.0 0.79 45 815 1.80 8.55 1.90 C.67 5 nr. 1375 1.88 8.79 8.18 0.67 15 375 1.65 8.75 8.18 0.64 30 1375 8.00 5.00 4.81 0.79 45 50 8.90 3.81 8.40 0.81 6 hr. 180 1.66 3.73 1.85 0.75 474 _\ 85. Influence of 15-minute re-introduction on the volune, pH end composition of ingesta passed from the duodenum r1 0) C H (D _____ .- Dry Organic Tine Volume matter matter Ash min. ml. pH i g g 5 . 8.75 . e 0.77 1087 '32 0055 8.79 8 0.71 UMPLD‘HB (COOK 1 9 8.18 1.5; 0.60 1 3 4.0 P If a FJFWJFJ +JFJFHA 15 1830 .94 3.35 8.58 0.83 30 300 .88 8.95 8.11 0.88 45 710 .78 3.17 8.48 “.75 8 nr. 400 .58 8.10 1.47 0.64 1; 160 .44 1.85 1.19 0.6 30 400 .08 3.86 8.44 0.8 45 910 .95 3.73 8.86 0.8 3 hr. 65; .88 3.50 8.61 0.8 Qinomq QDQHSO) 15 415 .85 8.65 1.88 O. 30 790 .30 4.91 3.83 1. 45 930 86 3.93 3.05 0. 4 hr. 150 .85 8.91 8.14 0. Hrebw~ FW4D‘H FH4PVF’ \I-QOQ \7LDO-x7 15 975 .88 3.51 8.83 0 8 30 1400 .07 4.88 3.81 1. 7 45 400 .58 8.78 1.99 0. 3 5 nr. 570 .80 3.08 8.85 0. 8 15 1580 8.08 3.64 8.79 0.85 30 440 1.78 3.65 8.89 0.74 45 540 1.90 3.44 8.59 0.73 6 hr. 1850 1.83 3.44 8.55 0.78 475 leole 32 Influence of onthuous re-introduction on the volume, p5 and composition of ingest? passed from he duodenum Dry Orgenic Time Volume netter wetter Ash min. 81. p4 % fl 8 15 170 8.8. 3.40 8.68 0.78 30 855 8. 9 3.33 8.60 0.73 45 65 1.87 3.86 8.6 0.65 1 hr. 980 1.80 4.81 3.54 5.68 15 975 8.11 4.9 4.19 0.79 30 350 1.96 4.35 3.5 0.76 45 350 8.01 3.98 3.86 0.66 8 nr. 755 8.10 3.59 8.84 0.75 15 1150 8.05 3.81 8.99 0.88 30 330 1.95 3.60 8.86 0.74 45 345 1.73 8.96 8.31 0.63 3 hr. 880 1.97 3.84 3.09 0.74 15 1000 8.00 3.88 3.06 0.74 30 630 8.05 -3.56 8.8- 0.74 45 605 8.08 3.87 3.13 0.76 4 hr. 300 8. g 8.95 8.86 0.69 5 585 1.90 8.73 8.18 0.68 30 690 1.85 8.87 8.84 0.64 45 800 8.08 3.17 8.51 0.67 5 nr. 955 8.18 3.65 8.99 0.66 15 875 8.10 8.84 8.16 0.68 30 690 8.00 8.94 8.84 0.70 45 710 1.85 8.88 8.1/ 0.71 6 nr. 760 1.94 3.45 8.78 0.73 476 leble 35. Influence of continuous re—intraduotion on the volume, p3 end composition of ingesta pessed from the duodenum Lry Orgenic Tine Volume Letter matter Ash 818. 81. p4 g k a 15 105 1.67 3.84 3.09 0.75 30 750 1.90 3.04 8.45 0.59 45 750 1.60 4.76 4.06 c.69 1 nr. 1150 8.13 4.99 4.06 0.94 5 900 8.19 4.09 3.18 0.9 30 405 1.98 3.3‘ 8.65 0.74 45 665 1.95 3.7 8 0 3 9 ('3'? 8 gr. 1085 fi>q C>Oto " ' Q. ‘ H q o q #3 5 565 1.96 8.8 8.33 0.54 30 618 1.65 8.8- 8.88 0.68 40 510 1.99 3.58 4.80 0.65 3 hr. 650 8.00 3.37 8.64 0.71 15 360 1.98 8.73 8.18 .6 30 545 1.98 8.83 8.80 0.63 45 750 1.96 8.53 8.07 0.59 4 nr. 1140 8.01 3.83 8.68 0.6 15 480 8.16 4.89 3. 6 ’.61 30 :5 1.94 8.6i 8.85 5.63 45 75’ 1.94 8.75 8.14 0.6 5 nr. 630 8.18 8..9 8.86 0.63 15 970 8.00 3.5 8.9 0.64 30 75: 1.95 3.94 3.89 0.66 45 535 8.07 3.48 8.73 0.64 6 nr. 780 8.00 3.07 8.43 0.64 I I 477 bm.ofl 63.0m ww.ba mm.® av.ma nH.Hm mm.¢ mono w H>.Qn mm.mw mm.mH Nm.m nn.©q ma.mb no.4 move a m©.mH mm.om mm.ba ma.w mb.mu mm.om no.0 3m;u w om.ma ab.m. wm.ba mb.m 69.nu 00.0m on.m Onon w mb.ma m§.mw no.6H HD.¢. wn.ou .4u.©o nn.w “fume u ow.HH uw.bv Hm.©a H§.w mm.ma om.mm vb.m owno H l!!!ll1!l!t!»-!t:1:11;!!!l H lento! .: R .H3 .9: £84 pomupxm pooflg poappxo Anu.wxmv poppma mepma oasaob mafia mopwucmmoppfia mCSLo pmmpm cfimuomm oagmwpo mam '1 ll .I‘li' Illi‘l';|!l|»l‘lll I! adamwosu 5H5 3358 Umummm mpmouua 90 mod Hmomawo 58¢ megao> emu so soaposwoppgalog 0: mo oesosamcH .84 magma 478 00.44 .4.04 40.04 04.0 44.44 00.04 40.n 0004 0 04.00 40.04 40.04 0m.0 34.44 00.04 44.0 0444 0 44.4- 00.04 40.44 84.0 44.44 44.04 40.4 0444 4 04.40 00.44 40.04 40.0 n0.n¢ 44.40 00.4 0244 n 00.44 44.44 40.04 40.4 40.44 0 .00 44.4 0044 4 04.44 04.44 40.44 0m.0 44.44 40.04 40.4 0400 4 ....... .I!!s :iii!l - -1. 44 .45 .43 3.4 pomppxm 44044 pomnpxm 404.044V 404403 404449 04040> @345 mmLMIuowoLpaa @0540 Loflpw Campopm oacmwpo mpg MO Q .204p4m0é500 044 0gs4o> 004 50200000 004 304% 000004 mummus4 so n04posvoppc4amg 0c 40 moaosaaqH .04 04005 00.04 00.4w 04.44 40.4 H0.0» 04.40 00.4 0404 0 00.4w mm.mu 00.04 00.0 m.4u 40.00 04.0 0004 n 43 44.44 00.00 40.74 am 4 00.44 00.m0 00.0 0400 4 M . 00.04 0m.04 00.44 m0 0 ua.0n 44.40 mm.» 0004 m 04.04 wm.mm 00.04 no.4 0m.0H 00.40 00.4 0008 u 40.04 00.48 40.44 44.0 40.42 00.mu 04.4 0000 H I & u a .45 .42 £04 40044x0 40444 40044x0 404.0440 404400 404403 033404 0040 0044:20004444 00340 40H4m 240404& 0420040 040 00200000 024 3044 000000 0400024 40 20444000000 020 00240> 034 20 204405004424104 04:245n04 40 002034424 s mm.mq mm.bq mo.ba mo.© mm.mu ma.«b mm.n onbn m ma.vu a©.mq Ho.ma $0.0 ¢H.Qu om.om me.w wwwn m 0 om.flu Ho.mm wm.ma mn.m mm.oa oa.wb ww.¢ mama w MW Hm.ug @Q.mu ma.ba mH.© b5.¢u . mo.bb no.¢ swag n Q¢.w2 bw.mn mm.wa m¢.© ma.ba mn.ob mw.n o¢©q J mw.oq mm.ma ao.va um.u ma.bo aa.wb Hm.q 000a H .1 Nil xx . 3 . a: £m< pouprm mefim pomgpxm “ma.m4gv pmppma hmppms masao> mafia mmgwImeogpam muzgo pmnpm uflmpopm oagmwpo mam Escmoosw mun £099 Cowman mummwQH no cofiuamowioo mug masao> mgp so soapospoppsalvg mpzcfialoa yo mogmsawaH .un magma \1 O LI \2 ' 3 Kl) g \1 r0 H LO H B 10 w w J 03 u) w L Q ‘0 ’3 x ) n w J (O mm.dd w&.mu Mm.uH m®.© um.ml “O.§b m¢.m ;fl0n O 1 mafia)“ Hm‘ZOm ©D.mH Owiw JDZNQ. 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Inf1ueLce of 311 an the volume, p3 end ccmposition or in esta Leased frou the duodenum ‘1 Dry Orgpnic line Volu4e matter wetter Ash min. ml. pH fl % % 1040 4.15 4.99 18 4.4.4 30 570 4. 5 4.78 4.31 0.47 45 510 4. 5 4.94 4.35 0.58 1 hr. 740 4.19 3.15 4.55 0.50 lb 56 4-14 4.85 aobO 0.63 30 1340 4.19 4.55 4.07 0.50 45 1400 4.40 4.79 4.4 0.55 4 hr. 159 4.14 5.19 4.54 0.55 l; 1503 4.10 3.b0 4.59 0.61 30 750 4.00 4.71 4.13 0.59 45 400 4.00 4.49 1.94 0.58 3 .r. 450 4.00 4.43 1.93 0.5 15 795 1.98 4.87 4.1: 0.5 30 770 1.94 4.65 4.15 0.5 45 555 4.09 4.55 4.14 0.53 4 hr. 400 4.01 4.57 4.14 0.5 15 470 4.03 4.59 4.04 2.57 50 790 1.99 4.5 4.01 0.49 45 1040 1.54 4.04 4.14 0. 0 5 hr. 740 1.94 4.79 4.30 0.49 15 995 1.80 3.14 4.57 0.57 70 890 1.90 3.44 4.59 0.5 45 300 1.95 3.34 4.75 0.57 5 hr. 550 1.94 3.55 3.00 0.5 15 840 1.90 3.53 5.05 0.5 30 540 1.85 3.59 3.04 0.5 45 395 1.90 3.34 4.78 0.5 7 nr. 555 1.99 3.53 4.97 0.5 04 Q I H . 0(7 0 O (O (O (O (O (PCflCDU n FH4FJF‘ 0H\t r p h b U~l .. m ¢ (3 ()1 (17 (31 <)> QLDQO Qwflhfi $ b p U” '33 \7 C) hr. 305 .J {J L ,2 . . a Q . . . 4 ~ . V ..v V "..v ..‘ ...v v LUV .~ ..v .-v ..v .\J 49 V r.» .4: ,b J lb, 4 ,1.» .v ,9 ..VV 4 1.3 .: .1. . 1.3 4. .1 if) .2 4 .4.) 2.; .4.) :_. .41.: 1 u . . . 0 u . g . ~ - o n . . v a ¢ o 4 ¢ . a u leole 10. (Continued) Dry Organic Time Volume wetter matter Ash 14111 0 “.1 a pH 70 IL/é 55 1. 545 1.90 3.97 3.40 0.57 50 450 1089 5081 s'bb 0059 5 450 1.91 4.11 3.50 0.51 9 nr. 345 1.89 4.10 3.57 0.54 5 955 1.90 4.18 3.44 “.75 10 HP 1530 1.91 4.49 3.78 0.54 10 770 4.00 4.84 4.27 O. 5 45 740 4.00 4.05 3.53 0.5 11 nr. 400 .99 4.01 3.44 0.5 1; 47 1.94 3.ez 3.45 0.57 so 45 1.93 3.50 4.95 0.50 45 7e 1.97 5.00 3.08 0.58 14 nr. 33 1.91 4.13 3.50 0.53 O) OCDC‘O1 C009: 3 1.93 4.34 3 8&- (.45 30 49 1.95 3.71 3 41 0.49 45 71 1.91 3.54 3.05 0.58 13 Ar. 95 1.97 3.58 3.14 0.55 15 715 1.90 3.59 3.05 0.54 30 770 1.90 5.90 3.48 0.54 45 580 1.88 5.81 3.35 0.45 14 hr. 395 1.85 3.84 3.47 0.55 15 540 1.85 3.35 4.79 0.55 30 740 1.90 3.43 4.70 0.57 45 790 1.94 3.34 4.81 0 51 15 hr. 745 1.78 3.39 4.75 0.54 5 545 1.91 3 58 3.41 (.45 30 450 1.91 3.54 3.04 0.50 45 390 1.95 5.57 3.13 0.54 15 hr. 350 1.83 3.40 4.55 0.54 ,...~ 1» l .\J ifiu : ...‘ l 1 p u C 4 .MJ 4,2 . .r. J l. a.» v wL1J :u 9‘ v V 0 iv ,J C 1.0 1%. ..v 1 L 1801a 10. (Continued) Dry Organic Tiue Voiume _metter Latter Ash ‘ ._ . L.. x. A‘Ol Li 0 “Al 0 p; ["0 1"0 ..0 .L 9 C C" C 61 10 00 (Thurman O®(O@ tb \N o O " (T‘ (T) 4 ‘ ‘::u _L / 51;". UMP w LN me-J C) 5 (U 0: U“ O H H }—’ F5 l‘-‘ (l, (1 '0 (1‘ C U' VJ (V 0 0 0 0 0 490 1.66 5.56 1.84 0.52 50 510 1.96 5.41 b.50 0.61 40 160 1.66 3.13 2.60 0.53 1: hr. 4L0 1.90 3.07 b.43 0.63 16 470 1.92 5.30 2.64 0.46 30 COJ 1.66 3.b1 9.71 0.50 40 500 1.96 5.67 3.60 0.47 9 hr. 490 1.60 5.69 3.LL 0.46 10 490 1.91 3.67 3.19 0.45 30 L90 1.69 5.73 5.50 0.48 =0 560 1.66 5.49 b.55 0.64 LU nr. 650 1.90 3.31 b.53 0.65 16 460 1.90 4.67 6.55 0.62 00 060 1.9L 4.,9 6.53 0.65 45 390 1.91 3.L1 1.53 0.6% L1 hr. 596 1.91 b.99 4.36 0.64 16 410 1.90 p.73 1.09 0.64 50 4LU 1.9; b.5- 0.0; 0.61 40 760 1.90 b.7L 5.15 0.60 a; nr. 490 1.94 a. 4 b.00 0.64 10 470 1.95 6.40 1.73 0.5b 50 400 1.90 4.60 .99 0.60 40 300 1.66 9.66 L.L4 0.61 :5 nr. 170 1.66 z.95 L.L9 0.63 10 690 1.69 9.6; 6.05 0.59 30 560 1.91 c.65 4.09 0.64 46 470 1.90 6.89 5.25 0.63 L4 hr. 695 1.69 b.90 9.29 0.62 t a I (J H (fl J "zu .L p. r—w ( ( N‘- (.. al‘ ~u.+-' (7‘ PI‘C‘L Cw!" ( ,1 (I ( 4!“- -———-—- ~———.—,—.——-———. ~- CO (0 Inf1uenoe of %41 on tge volume, of ingeste pessed frog the duodenum p9 end composition Dry -a. Organic gime Toluae matter matter Ash bin. 41. p? p 5 fl 5 540 1.95 9.70 9.99 0.46 50 470 1.64 9.99 4.45 0.46 45 1140 1.66 4.45 9.0; 0.59 1 nr. 1130 1.54 9.49 4.04 0.57 15 905 1.66 4.45 9.09 0.41 50 1050 1.76 ‘.64 4.41 0.43 45 970 1.60 9.56 9.15 0.41 4 hr. 195 1.76 9.54 4.07 0.47 15 190 1.74 9.36 1.95 0.43 50 660 4.00 9.67 4.41 0.45 45 540 1.69 3.19 4.67 6.45 5 hr. 650 1.66 9.94 4.49 0.59 15 650 1.6; 4.65 4.40 0.43 30 640 1.77 9.70 4.9o 0.44 45 440 1.73 4.60 4.34 ”.46 4 nr. 450 1.75 5.07 4.57 0.49 15 190.1 1.64 3.41 4.67 0.53 50 1110 1.69 3."5 4.79 0.54 45 1460 1.94 5.45 4.75 0. 9 5 hr. 65 1.96 4.96 4.55 0.45 15 973 9.05 5.17 4.66 0.49 50 750 1.69 5.15 4.65 0.50 45 650 1.67 5.50 9.64 (.47 6 or. 965 1.99 5.56 5.10 0.46 15 4 4.01 5.66 5.16 0.50 50 9 4.03 5.56 5.14 0.44 45 6 1.66 5.49 4.96 0.59 7 hr. 6 1.75 3.75 5.44 0 49 (001 (C‘ H (3‘; l--' I“ <1 t—J (O (In D 07 O O 01 C. C C O (V H H H H O O O (O \? O) 03 (I) (1’ L0 LT) #5 (Ni 0 '~ 0) (A UID (C) [Y {D (D .~ 1‘) l‘ a") \D (N Mix m (V'- ()1 (‘71 CD (3 {3 =13 1941e 11. (Continued) —-—— "" Dry Orgenic line Volume wetter metter Ash Iain. :41. pH ;6 fl ’3 o 1510 1.99 4.66 4.10 0.56 50 66 4.00 4.50 3.94 .56 45 750 1.91 4.19 5.65 6.49 9 hr. 45 1.95 4.09 3.64 “.46 15 995 1.99 4.46 3.76 0.51 50 1460 1.90 4.17 3.6: 0.54 45 1075 1.69 4.64 4.10 0.54 10 gr. 1410 1.74 3.97 5.50 6.47 lo 1155 1.71 5.69 3.59 0.50 50 415 1.70 5.66 3.17 0.51 45 1060 1.64 4.50 5.64 0.46 11 hr. 750 1.69 4.09 3.61 0.46 5 1540 1.96 4.77 4.45 0.54 50 105 4.01 4.11 5.65 0.46 .b ..- __ .... -.. .— 14 hr. 400 .60 3.03 9.61 0.47 o (0 so 530 HHHH H (“£003 030?“ lbkflUwVw OCHCNO ¢~$+403 w 0 \7 3 ¢ \7 g \7 C)( 15 1.94 5.57 5.10 0.43 30 r50 1.94 5.45 4.76 0.47 40 090 1.79 4.87 9.49 0.44 14 n E 5 1.69 5.49 9.84 0.45 15 870 1.43 5.07 9.61 6.45 50 100 1.74 5.67 3.99 0.39 45 1034 1.85 3.69 5.13 0.49 15 1500 1.67 3.30 ‘.65 6.47 lb 655 1.76 9.75 9.97 0.45 50 34C 1.76 5.60 3.10 3.50 45 690 1.84 5.49 9.90 0.:9 15 590 1.79 5.41 9.94 0.47 Teole 11. (Continued) _g‘“ Dry Organic lime Volume nettew Lette? Ash ...11’. . ...1 . p3 L ,‘4 15 835 4.09 3.69 3.14 0.57 50 4360 1.96 3.47 3.06 0.:0 45 1340 1.98 3.86 3.37 0.51 17 hr. 190 4.14 4.40 3.75 0.43 15 56 4.00 3.13 4.74 0.44 30 o;0 4.04 4.91 4.46 0.45 45 79, 4.09 5.87 3.36 0.51 16 nr. 1410 4.10 3.41 4.90 0.54 15 333 4.14 4.44 1.96 0.4Q 30 1410 4.04 4.41 1.99 0.41 45 664 1.90 4.45 1.84 0.44 19 hr. 513 1.84 4.41 1.79 0.44 o 945 1.66 4.64 4.43 0.40 30 1075 1.64 4.34 1.99 0.~5 45 1460 1.60 4.43 1.99 0.44 40 nr. 1600 1.64 3.41 4.97 0.44 o 1440 1.66 3.30 4.99 0.44 50 450 4.00 4.83 4.39 0.45 45 730 4.04 4.63 4.19 0.43 41 gr. 1140 4.15 4.69 4.45 0.43 15 166 4. 6 4.63 4.34 0.5 30 1144 4.40 4 65 4.44 0.41 45 :30 4.05 4.30 1.49 0.44 44 gr. 1640 4.04 4.66 4.44 0.44 15 440 4.05 4.75 4.39 L.36 30 1075 1.96 4.34 1.93 0.39 45 500 1.90 4.13 1.77 0.35 43 hr. 1040 1.63 4.-7 1.66 ‘.38 5 375 1.85 4.30 1.97 0.33 50 530 4.00 4.54 4.16 0.34 45 1410 4.00 4.94 4.47 0.47 44 gr. 360 4.00 4.85 4.37 0.47 --...V v ..J .10 s. 4 4.4 .u L ..J ....v fh‘ 7v L/u .I¢.\,J ..’: .4 ...V ...v 7*.) L9 ..\~ hf n .«ba *. v J C. v 4 4 494 leole 14. Influence of 344 on the voluue, pE Fid 099P051t10n of in este passed fro; toe duoaenum Dry Organic lime Voluue Letter Letter Ash 1.5112 0 I“: o p: ‘r- ’0 :‘L 1: 1350 4.33 4.01 3.64 0.49 50 4160 4.46 3.66 5.17 0.5 45 1340 4.43 4.18 3.66 0.5. 1 HP. 1010 4.55 5.64 3.49 0.54 14 1640 4.48 5.87 3.31 0.*6 30 590 4.4: 4.13 5.64 0.55 40 :40 4.48 4.63 4.10 0.57 4 gr. 1140 4.34 4.44 3.65 0.56 15 450 4.34 4.59 3.54 0.57 30 860 4.44 3.69 5.57 0.54 45 910 4.44 3.91 3.58 0.55 3 4 . 950 4.44 3.81 3.44 0.57 15 595 4.40 3.99 5.44 0.55 30 930 4.18 4.05 5.41 0.64 45 460 4.06 5.74 3.19 0.55 4 hr. 140 4.05 3.51 4.94 0.59 10 940 4.40 4.75 4.17 0.57 33 1410 4.15 4.54 5.79 0.56 c 990 4.40 4.47 5.61 0.66 C nr. 740 4.44 4.44 5.64 0.64 15 430 4.13 3.50 4.30 0.60 30 005 4.10 3.60 4.97 0.63 44 1340 4.14 4.01 5.44 0.58 6 nr. 1615 4.00 3.64 5.54 0.50 1“ 745 1.94 5.53 5.05 0.50 50 995 4.00 3.84 5.31 0.51 45 565 4.00 5 40 4.76 .63 7 JP. 48; 1.90 5.41 4.59 0.63 15 390 1.68 3.19 4.65 0.53 30 740 1.68 3.09 4.55 0.54 45 770 1.68 3.43 4.84 0.41 6 nr. 480 1.70 5.01 4.6 0.39 Eagle 14. (Cantinued) Dry Orgenic Lime Volume matter matter .. ' - , ' ..', cr/ L411; 0 114.1. 0 /0 /‘C *0 41; 15 140 1.71 4.94 4.5 30 460 1.60 5.14 4.55 45 650 1.6: 5.57 5.10 9 hr. 9.- 1.96 3.66 5.44 15 760 1.96 5.6; 3.19 30 65. 4.05 -3.36 4.7 45 510 1.96 3.14 4.5 10 nr. 645 4.04 3.46 4.: “5 H (O O Q +9 l" 01 15 940 1.90 3.79 5.4 50 330 1.60 3.65 3.0 45 700 4.04 3.70 5.0 11 hr. .914 4.14 4. 4 3.4 14 1360 4.11 3.99 3.56 30 1410 4. 9 4.41 3.66 44 600 4.15 4.44 5.65 14 hr. 350 4.03 5.45 4.6. 1' 600 1.95 5.14 4.57 30 970 1.91 5.35 4.77 45 634 1.97 3.45 4.66 15 Jr. 415 1.90 3.43 4.6” 15 345 1.99 5.01 4.44 30 790 4.05 5.19 4.66 45 995 4.04 5.67 5.09 14 nr. 690 4. 4 5.95 5.47 5 565 4.14 5.46 4.94 50 670 4.13 5.09 4.54 5 545 1.99 3.01 4.45 5 “r. 495 1.90 4.90 4.36 15 370 1.76 5.50 5.05 30 60 1.94 5.46 3.04 45 540 1.96 5.70 3.46 16 hr. 1495 4.01 5.64 3.36 (Q) C) O C) “,1 C) O (3 CT) 03 (D U1 (N [V 04 (O C. (‘3 (3'1 0‘) (in (I) (O Q" F4 (0 C30 C3 ’ {11) C? O O C3 ()1 ()1 C“: C.‘ #3 (O (71 O7 Q) (0 C14 \7 (")1 O 0000 (510‘! \ .__/ f {1) ()1 (V? CD ()1 C)" O1 O") H \N-Q . :43 $+b¢\# Q C) (J O ()3 494 Taele 14. (Continued) Orgenic Time Vo1ume mstter L. 1.”. . ..‘-l . p :i )5 a; Dry matter 15 1440 4.14 5.79 5.43 30 1350 4.07 3.54 4.93 4; 9 0 4.09 5.45 4.94 17 nr. 500 1.90 5.44 4.77 15 490 1.95 3.19 4.65 30 640 1.90 3.45 5.01 44 500 4.00 3.55 5.09 14 hr. 60; 4.04 5.71 5.05 15 900 4.15 5.46 4.99 50 ECU 4.0-D 3.450 4.69 45 1000 1.96 5.54 5.05 19 hr. 735 4.00 5.51 4.95 15 965 4.06 5.69 3.44 30 490 4.14 3.64 3.44 45 1100 4.40 5.60 5.05 40 gr. 675 4.40 5.47 4.94 15 640 4.00 5.45 4.97 30 190 1.99 5.56 5.05 45 545 4.19 3.60 5.04 41 gr. 1465 4.44 4. 6 3.47 15 1340 4.39 4.00 5.36 30 1370 4.39 3.5 4.95 45 435 4.59 3.47 4.91 44 hr. 460 4.15 3.49 4.79 15 440 4.00 3.31 4.64 30 945 1.96 5.6“ 5.13 5 1195 4.05 3.64 5.04 43 nr. 1100 4.45 3.34 4.94 5 460 4.40 3.04 4.5 30 36 4.45 3.46 4.76 4‘ 770 4.19 3.71 3.06 44 hr. 1440 4.45 3.75 5.17 #53450) C) (3' 43 (3 GOOD 00. 14>- 01 (Ln (p. H +43 01 :\_ L.“ #5145 ()3 ('j'! ()1 $0145 :: (U H -\) . L \ ’2} ()1 (n U) .15 ()1 \7 0.2" (“D 01 (D. (n N3 (O 07) (\1‘ @- Obie-010 0105014“ CD+¥>O $450404 Hb ocooao l‘ O l‘ (E) 45 u: U! HUQH 4 15 111" . H (71“. \7 iv 740 1.98 3.55 4.93 90 80 1.94 3.84 3.44 4' 540 1.94 3.70 3.08 13 hr. 490 1.94 3.45 4.85 (O Q) \7 ()3 (D (O (O l"? \‘1 37 (D ()3 #- U) (N (L) ()1 \7 (D (‘5) (O :01) (D (A Q 0 +15 0) 04 (v 4> 0" C“ (D (D Q 03 (D O‘) \7 .' if ) i1) (004 L30 0 ()3 m ()1 O 497 Eagle 13. (Continued) Dry Orgenic Time Volume Letter Letter Aeh Lib. 41. p3 m g p 15 L00 b.00 3.37 4.71 0.66 30 300 1.60 3.03 ;.51 0.55 45 330 1.70 3.40 5.6 0.59 17 nr. 1040 1.80 3.55 3.01 0.54 15 665 1.66 3.81 3.16 0.63 30 500 1.9a 4.06 3.47 0.59 45 130 4.04 3.19 4.5; 0.66 16 hr. L05 1.9 3.30 9.63 0.62 15 600 1.79 3.5" 2.95 0.61 30 8C0 1.91 4.17 3.54 0.63 45 665 1.99 4.77 4.11 0.66 19 hr. 745 1.90 4.44 3.6; 0.65 o 350 1.04 4.0; 3.43 0.59 30 570 1.5; 3.71 3.10 0.61 45 530 1.53 3.40 4.97 C.5~ LO hr. 1090 c.00 3.99 3.34 0.64 15 640 L.O5 4.67 4.0; 0 66 I0 700 5.11 5.10 4.46 0.69 45 50‘ c.00 5.0L 4.39 C.63 a: nr. 340 1.64 3.3b 2.74 0.59 5 930 1.96 3.83 3.13 0.66 30 350 1.76 3.14 z.62 0.52 45 570 1.30 3.56 3.01 0.55 LL hr. 770 1.99 4.73 4.1L 0.66 15 L 0 1.98 4.16 3.47 0.65 30 LCD 1.79 3.67 2.45 0.62 ‘5 710 1.5: 3.35 5.50 0.55 L5 nr. 360 1.6; c.98 L.41 (.57 e 560 1.65 3.69 3.30 0.56 30 650 1.9; 4.9a 4.31 0.61 4 £70 1.9: 3.64 3.17 6.67 54 hr. 170 1.94 3.0; p.44 0.59 iecle 14. Influence o ‘5 T I )9 n I _ "‘ .I lrgeste pesseo on the Volume, pH and comgosition from the duodenum Dry Organic iiue Volume metLer Letter Ash 51L. 51. p3 € fl 4 15 L00 L.30 3.33 L.9L 0.5L 30 715 L.61 3.50 L.95 0.59 45 1L50 L.14 3.55 L.97 5.59 1 nr. 166” L.4L 4.40 3.78 0.62 15 635 L.ou 5.50 4.68 0.81 30 645 L.Lo 4 5 3.90 0.67 45 630 L.11 3.95 3.41 0.54 L hr. 605 1.69 3.53 L.E9 0.60 15 550 1.86 3.31 4.81 0.50 33 190 L.06 L.6‘ L.06 0.54 45 400 1.30 L.76 L.L5 0.50 5 nr. 760 1.75 L.9L L.31 0.61 15 650 1.47 3.L1 L. 4 0.61 30 610 1.39 3. 6 L. 5 0 6 45 450 1.65 3.L5 L. L 0.55 4 or. 560 L.0L 5 ' 1 0.73 § 0 I owned FAGuqcD 15 90 96 3.7 3. 4 0.63 50 660 L.OO 4.54 3. 7 0.66 45 990 4.00 4.01 3. 6 0.65 5 hr. 990 L.07 4.03 3. 3 0.70 lo 540 c.09 4.08 3.45 0.50 )U 300 (v.05 41.43 5.5L. 0.70 45 530 1.65 3.50 b.63 0.7L 5 nr. 810 1.82 3.66 3.01 0.70 15 545 1.99 3.94 3.35 0.60 30 660 1.90 4.08 3.39 0.39 45 :65 1.9L 4.95 4.LL 0.76 7 nr. 595 L.06 4.35 5.58 0.73 15 650 L.06 4.59 3.90 6.6" 30 L00 L. 5 3.76 3.05 0.71 40 1500 L.Ul 5.00 4.LE 0.72 5 hr. 1000 L.08 6.03 5.16 0.61 6 (a) (O Dry Orgenic lime Volume matter matter Ash ILlL. 141. ;pfi )3 f5 i 15 690 L.41 5.60 4.90 3.71 30 530 L.OL 4.63 4.06 0.57 45 395 L.03 4.49 3.79 0.66 9 hr. 75 L.46 3.59 L.61 0.75 15 490 L.0L 4.LL 3.63 {.59 30 915 L.00 3.6L 3.L7 0.55 45 950 1.9: 4.05 3.41 0.64 10 nr. 1190 1.90 4.56 3.79 0.77 15 1990 L.13 4.74 4.14 0.60 30 190 L.O5 4.06 3.57 0.49 45 470 1.67 3.83 3.33 0.50 11 nr. 650 L.0L 4.L6 3.75 0.51 15 955 L.00 4.14 3.57 0.57 30 1140 L.09 4.04 3.55 0.53 45 300 L.31 4.39 3.86 {.55 1L nr. L35 1.64 3.L7 L.95 0.4L 5 670 1.93 3.Lo L.6L 0.44 30 500 1.90 3.36 L.93 0.43 45 795 1.69 3.54 3.04 0.: 13 nr. 630 1.9L 3.74 3.L9 0.46 5 110 L.10 L.63 1.96 0.67 30 555 1.90 3.37 L.91 0.47 45 505 1.90 3.L1 L.79 0.49 14 nr. 990 1.90 3.38 L.81 0.59 5 735 L.06 3.53 L.96 0.67 30 950 L.14 4.L1 3.64 0.57 45 130 L.L1 3.36 L.89 0.44 5 Hr. 5L0 1.93 3.51 3.00 0.50 5 1010 1.9L 3.36 L.6 0.56 30 960 L.00 3.7L 3.11 0.6 45 965 L.05 3.63 3.03 0.61 5 hr. 11L0 L.08 3.74 3.09 0.69 |.|u_1 rC 01‘ 3‘.‘ 500 'sble 14. (Continued) Lry Organic lime Volume matter matter Ash . - .. -. 'T 9'" .-. 141113 0 [LA]... 0 p“ /C ['0 '19 15 330 L.00 3.4L L.75 0.65 )0 035 1.70 5.51 L.13 0.52 45 530 1.55 4.64 L.11 0.47 17 3?. 470 1.53 b.85 b.34 0.43 5 550 .5L 5.08 L.47 0.61 0 565 .60 L.56 L.17 0.45 45 160 .76 L.39 1.36 0.53 12 LP. L00 .6 L.LL 1-74 0.48 0 L 4.15 0.44 30 L70 .56 L.oL 1.99 0.50 45 900 .61 3.10 L.49 0.61 9 hrn 65” .86 3.46 4.65 0.57 o C,“ \7 C; T; 04 +5 C \‘I Crvkhv O U‘ C O D H O 3010 A. U~ “c: ( {0 0‘: <0 \1 O 5: {N O 0‘: I—‘ CH (A (\f (A C H-. L») [11‘ - I” H ue (\fQJ;¢-43 #5040404 01 15 1130 L.41 .50 3.66 0.73 30 445 L.46 .63 4.06 0.77 45 365 L.lL .07 L-40 9.67 L1 hr. 6L5 1.90 .66 L.L0 0.49 15 490 1.60 L.31 1.71 0.60 30 415 1.6L L.44 1.91 0 53 45 770 1.66 L.76 L.L6 0.5L LL hr. 455 1.66 L.67 L.15 0.56 5 3s0 1.75 L.59 1.99 0.60 30 170 1.66 L.37 1.93 0.43 45 L65 1.75 L.50 1.96 5.56 L3 nr. 760 1.61 4.61 LoL5 0.5L 5 1375 L.09 3.31 L.76 6.55 30 153“ L.13 4.31 3.71 0.0 5 715 L.4L 3.67 L.99 0.71 L4 nr. 315 L.19 3.L7 L.64 0.64 .\.J 501 able 1:- Influence of £41 04 the volume, p3 end CJKPOSitiOH .- 4.. - ,. ,. "b ... 4—‘ A .. .. q; 1n,eete pegged Irom pflc duodenum I‘ . “\044 Cl.- C)! C‘ (3‘ +1?- (1* F‘ 4“ CH C) ('31 (‘3 (D (II (i‘ rfikfiH 544 N‘ \7 01C: ('5‘ Dry Organic Voluue Letter wetter Ash 4.1.. 13:1 ;5 {c f. 1110 4.45 4.50 .84 0.50 1070 4.45 4.75 .00 0 75 45 4.33 5.19 .41 0.95 (“womb “(3.5.4554 1100 4.58 5.41 .48 0.9 1445 4.59 4.5 .91 0.77 1055 4 50 3.79 .05 0.77 hr. 1010 4.45 5.45 .95 0.47 93 4.53 3.19 4.43 0.71 1540 4.4” 4.70 4.51 5‘. 5 440 4.50 4.54 1.77 0.75 hr. 590 4.47 4.45 1.94 0.54 540 4.19 4.37 1.74 0.?5 1470 4.40 4.39 1.73 0.59 950 4.40 5.07 4.36 0.70 nr. 1700 4.44 3.14 4.40 0.71 850 4.40 4.89 4.17 4.74 740 4.10 4.50 1.75 0.55 550 4.00 4.41 1.77 0.49 gr. 710 4.00 4.17 1.7; 0.43 1400 4.00 4.15 1.4 0.55 9&5 1.99 4.14 1.: 0. 5 910 1.95 1.95 1.5 0.44 hr. 740 4.44 4.44 1.9 0.44 700 4.19 4.44 450 4.43 4.10 1190 4.11 1.93 nr. 1050 4.1% 4.39 0101 F-J \) (D |-—' (0 (_ij‘, HIP-’i-‘FJ flu»: [‘07 1000 4.18 4.71 4.14 0 59 1045 4.45 4.7% 4.07 O. 9 490 4.45 4.53 1.E 0.73 nr. 855 4.41 4.55 4.08 0.45 504 18418 15. (Continued) .———-—.-—.~.— Dry Orgenic flue Volume metter matter Ash 5 555 4.41 4.70 4.40 0.50 50 480 4.45 4.81 4.57 0.40 45 810 4.14 4.54 4.40 0.54 9 nr. 1150 4.47 5.57 4.55 0.74 10 1000 4.46 4.97 4.35 0.59 50 580 4.44 5.15 4.58 0.51 45 450 4.49 5.55 4.95 0.59 10 nr. 840 4.48 5.54 4.74 0.59 15 C50 4.17 4.97 4. 9 0.77 50 750 4.14 5.14 4.58 0.55 45 450 4.40 5.44 5.08 0.54 11 hr. 500 4.50 4.85 4.54 0.57 15 ~— -- -— -- -- 30 1050 4.45 4.74 4.17 0.55 45 715 4.05 5.55 4.85 0.58 14 hr. 530 4.05 4.55 5.57 0.57 14 580 4.10 4.89 4.51 0.64 50 790 4.18 5.44 4.54 0.54 45 550 4.44 5.51 4.54 0.57 15 nr. 580 4.40 4.54 5.75 O-f7 5‘ (if; 4.45 4.64. 3.79 0.35 50 850 4.55 5.55 4.55 0.87 45 550 4.55 5.48 4.54 0.95 14 nr. 1545 4.55 4.90 4.04 0.91 15 1510 4.40 4.11 5.55 0.78 50 595 4.18 4.15 5.57 0.80 5 710 4.11 5.89 4.91 0.79 15 nr. 1145 4.10 5.71 4.98 0.75 5 1450 4.18 5.75 4 93 0.79 50 415 4.19 4.18 5.44 0.75 45 —— —- -- —- ~— 15 hr. 515 4.40 4.58 4.59 0.27 505 (V x J C) U; C‘ (M H H ‘1‘ V. J 1 "j ‘1 C W p. (‘5 pcfik: i-—’ (P 0 Ci- (V 'kufiF-J ' (D C.‘ 01 e 15 (Continued) Dry Orgenio Volume matter wetter Ash ml. pH 5 fl 5 4L0 4.11 4.34 5.55 0.94 580 1.95 5.54 5.04 0.5 hr. 510 1.95 4.05 5.50 0.75 515 1.98 5.91 5.47 0.54 570 1.94 5.50 4.75 0.74 590 4.00 4.55 5.74 0.84 hr. 90; 1.99 4.45 5.50 0-55 5/0 4.00 5.47 4.79 0.45 490 1.85 5.19 4.38 0.51 h . 545 1.77 4.59 4.59 0.50 650 1.89 4.47 5.71 0.56 500 1.95 5.54 4.9 0.55 555 1.80 5.50 4.84 0.49 770 1.83 5.08 4.5 0.49 835 1.81 4.84 4.41 0.55 915 1.7; 4.81 4.55 0.40 450 1.90 4.04 5.55 9.5 710 1°88 30L4 boEl 0043 nr. 850 1.77 4.54 1.9: 0.55 055 1.64 4.87 4. 8 0.59 775 1.55 4.55 4.07 0.55 504 Teole 13. Influence of 344 on the volume, p3 end composition or inieste pessed fPOm tne duodenum Dry Organic Lime Volune uetter netter Ash 1.; i 1'. o L l 0 pH ,2 ff) :5 15 880 1.84 4.79 4.14 0.54 55 950 4.0 4.41 5.78 0.55 45 545 1.90 5.45 4.57 0.79 1 750 1.98 4.90 4.04 0.87 15 840 1.95 5.84 5.11 0.75 50 1510 1.85 5.74 5.17 0.57 45 1455 1.81 5.57 5.0 0.55 4 785 1.81 5.95 5.40 0.55 15 51 1.8 4.05 5.49 0.55 50 1110 1.74 5.55 4.84 0.51 45 940 1.78 5.50 4.98 0.55 5 85 1.74 5.90 5.41 0.55 15 900 1.80 5.75 5.05 0.75 50 440 1.84 5.08 4.49 0. 9 45 570 1.85 4.74 4.04 0.5 4 1100 1.70 4.54 1.95 0.5 15 1070 1.74 4.95 4.57 0.57 50 540 1.84 5.44 4.95 0.48 45 530 4.04 4.C8 5.51 0.77 5 875 1.85 5.54 4.85 0.58 5 450 1.84 4.74 4.10 o 54 50 1490 1.70 4.85 4.41 0.55 5 515 1.70 5.]7 5.44 0.55 5 1140 1.81 4.51 5.75 0.75 15 955 1.78 4.14 5.55 0.57 50 490 1.81 5.47 4.74 0.75 45 850 1.85 5.58 4.95 0.75 7 dr 750 1.84 5.49 4.85 0.55 5 995 1.88 4.05 5.55 0.54 50 950 1.94 4.55 5.55 0.80 45 510 4.04 4.)5 5.47 0.79 8 550 1.95 5.4“ 4.57 0.77 (31 O ()1 ”sole 15. (Continued) Dry Organic line Volume matter matter .sh 4;“. 41. pH 4 4 Z 5 180 1.93 4.47 3.85 0.82 30 1550 1.84 4.47 3.88 0.59 18 815 1.99 4.47 3.73 0.54 nr 700 1.38 4.71 3.95 0.77 15 400 1.95 4.79 4.38 0.73 30 1190 1.89 3.31 4.48 0.84 48 890 1.83 3.58 4.91 0.88 10 a? 970 1.88 4.44 5.49 0.93 15 1050 1.98 4.5 3.90 0.88 30 788 1.91 3.77 4.98 0.84 45 1130 1.87 7.98 3.41 0.45 11 hr. 115 1.9: 3.08 4.50 0.58 18 818 1.80 3.01 4.45 0.78 30 880 1.88 3.54 3.03 0.51 45 515 4.03 4.47 3.84 0.88 14 hr. 885 1.89 4.59 3.71 0.88 5 880 1.81 4.31 3.73 0.58 30 1085 1.80 4.08 3.49 0.57 48 95 1.74 3.44 4.88 0.54 13 hr. 430 1.74 3.71 3.17 0.54 lu 745 1.71 4.00 3.33 0.87 30 340 1.59 3.55 4.88 0.89 45 315 1.81 3.88 4.94 0.72 ‘4 nr. 870 1.73 3.58 4.85 0.74 lb 430 1.77 4.59 3.77 0.83 30 540 1.90 4.33 3.84 0.79 45 810 1.98 4.37 3.83 0.74 15 hr. 800 4.00 4.73 3.98 0.75 E- 415 1.90 4.83 3.97 0.88 30 104- 1.83 4.84 3.93 0.89 48 740 1.75 4.44 3.78 0.83 18 hr. 400 1.77 4.84 4.03 0.80 Table l6. (Continued) Dry Organic Time Volume matter matter Ash min. Ll. pH 6 g g le '6“ .81 4.64 4.06 0.61 30 646 .7; 4.39 3.77 0.66 45 75 .66 4.54 3.76 0.56 17 “r. 650 .63 4.Ll 5.56 1.66 lb /00 .66 4.64 4.11 0.6? 50 ~LO .76 5.63 4.4: 0.67 46 960 .61 6.00 4.a£ 0.73 1; nr. 660 .60 4.05 6.53 0.70 16 660 . 5.47 4.9 0.57 50 l‘lO . .5.64 3.03 0.61 45 ’ 3.45 6.64 0.56 15 hr. 4L0 . b.64 4.z4 0.60 H I‘ 0) CD HF-‘Ht—J F—‘F-‘l-‘l-J l—JF-‘l—‘t—J HHF-‘H l—‘HI—JH (NQU‘LD $900 10 57C .7~ 3.57 b.66 0.49 )0 550 .60 3.66 2.60 0.69 40 460 .70 3.zo 6.61 6.59 LO nr. 950 .64 5.40 2.61 2.67 16 540 .66 3.69 2.91 6.66 50 760 .74 4.56 3.9” 0.62 46 910 .66 4.67 3.65 0.65 L1 nr. 66: .90 3.16 2.4; 0.76 l; 740 1.60 4.5; 5.01 C.50 50 516 1.64 6.56 2.15 0.44 46 410 1.67 9.77 6.51 6. 6 LL 5?. 676 1.64 4.73 4.5b 2.41 lb 1070 1.7” 4.96 L.&8 L.67 60 000 1.66 4.69 b.0z 0.67 46 510 1.73 c.97 6.36 0.6z 4.3 --I’o 5350 1.64 p.87 ao3f C-SL l“ (x 03 \7 Lu C (V (I) C H H lr—J H \7 \1 “Q 0) C)‘ C)» H}- D U L, U1 we UJ (\ ()1 44>- (n (51 \ D' 4‘4 U“) h" :0 w 44 hr. 760 607 Hm.®H no.0m 46.9H fio.mmH ®H.0w Dana wm w 1 ma.ma mH.Hm no.m m©.m 00.0 ow.om mu.n 366a 64 mm.mH mo.mn me.w nm.oa Hu.mu Hw.ow wl.m swan in mm.dH ©4.Hw mm.w 6v.a Hw.¢m bw.am mm.n mama an mw.m ¢¢.on um.¢ mb.oa wa.mm nn.am mw.n Cuba on mm.mfl wa.on mm.v 96.3H ©H.mw 6.6Hm mn.w QJQH m 00.0u mm.bu Ha.m JH.HH u¢.mm 00.0m wa.n abwa ma av.ma mm.ma mo.w om.HH 6m.mm mw.am aa.n Gama 6H mm.6a mm.om ww.¢ mm.HH mo.m ea.um 6m.n Dana ma Hm.wm mm.mu 4H.m 66.3H 66.60 mw.am mm.u mama 0H 64.na mt.am 46.4 em.HH 64.4m 66.66 mw.m 6444 4H Hw.wa mm.un mm.n ma.ua mm.mn ma.wm mu.m name ma 64.5H nm.4n Hm.m mm.afi «6.46 06.66 uw.n coma 3H um.4a nc.mm H4.m mg.HH m..am ma.6m mn.n @346 HH mu.m 66.6. mn.m mH.HH mb.ow vb.¢m mm.n mawn OH m¢.m nu.mm mm.w @6.aa mm.gm «n.6w 06.9 ooma m ma.ba vb.mm 6a.¢ 6n.&a mn.um m.um w©.n 06w w oo.mfi mm.wm 6©.m ma.ua mm.nm oo.aw mw.m own& 6 ¢H.ou _m¢.m& mn.m w).ua ma.wmr ©®.»b 3H.m 04mg 6 ao.x2 Hw.ra aw.u wm.ga Ho.¢m 4m.6b ow.q Dawn 0 oo.mu ov.mu 6m.4 a©.ua 06.nm oo.mb mm.u ownu w «m.fl« mw.ow 6H.m wo.¢a Hw.um ©©.m6 a .n stun a 0m.NN mu.bg mb.m mu.ua wv.©m H¢.b§ OH.@ omoa J mm.flz 66.54 mm.4 44.na 4n.mm ua.mn 66.6 own» a u§1i1i1$1;1.. 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