OVERDUE FINES: 25¢ per day per item RETURNING LIBRARY MATERIALS: Place in book return to remove charge from circulation records INFLUENCE OF SOURCE AND LEVEL OF NON-PROTEIN NITROGEN ADDITIONS ON THE NUTRITIVE VALUE OF CORN SILAGE BY Ronald Lewis Boman A DISSERTATION Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Dairy Science 1980 ABSTRACT INFLUENCE OF SOURCE AND LEVEL OF NON-PROTEIN NITROGEN ADDITIONS ON THE NUTRITIVE VALUE OF CORN SILAGE BY Ronald Lewis Boman Four experiments were conducted to investigate the relationship of non—protein nitrogen additions to fermentation and the subsequent influence on the nutritive value of corn silage. A common objective of all experiments was to vary the level of NPN addition to corn silage and to compare ammo- nia with urea and determine their effects on fermentation or ruminant nutritional parameters. The first experiment (l-A) was designed to study the effect of urea, aqua-ammonia or an ammonia solution, each at three levels (.23, .46 or-.92%N) of addition, on silage nitro- gen and organic acid fractions during fermentation. The ni- trogen sources and levels were compared to a control corn si- lage receiving no additive. An added dimension was to com— pare mineral and disaccharide additives alone or in combina- tion with each low level of nitrogen source. Silages were eva- cuated of air and stored in 56 kg portions inside experimental silos. Silos were opened, sampled (5009) and re-evacuated of Ronald Lewis Boman air on days 1, 3, 5, 10, 15, 20 and 40 of fermentation. Tem- perature of silage during fermentation decreased over time and was not affected by nitrogen source or level. Silage final pH on day 40 was increased (P—<.05) by nitrogen addition, with the pH of the highest level of the aqua-NH4 and NH4-solu- tion treated silages remaining above 6.0. Lactic acid was in- creased (P<<.05) in silage containing the low levels of added nitrogen; However, lactic acid production was essentially eliminated at the highest level of addition to silage by the two sources of ammonia. Acetic acid levels were increased (P<<.Ol) by the same treatments which depressed lactate. To- tal nitrogen and total soluble nitrogen content of corn silage was increased (P¢<.05) by each incremental level of added ni- trogen. Water insoluble nitrogen levels in this experiment were unchanged by nitrogen additions to corn silage. Mineral and disaccharide additives had no consistent influence on si- lage fermentation parameters except that CaCO3 caused elevated lactic acid levels especially incombination with ammonia and lactose tended to cause lower silage pH values. The second experiment (2-A) was designed to study the effect of three levels of anhydrous ammonia (.24, .48 and .72%), with three levels of added water (0, .8 and 1.6%), on silage fermentation parameters and nitrogen recovery of corn silage harvested at 30, 35, 40, and 45% dry matter. Duplicate silage treatment combinations (56 kg each) were stored as in experi- ment l-A. Silos remained sealed until day 40 of fermentation. Ronald Lewis Boman Ammonia and water were mixed and added to silage at the si- lage blower to simulate farm conditions. Recovery of added ammonia, after 40 days of fermentation, decreased with ad- vanced silage maturity and increasing amounts of added ammo- nia. Over all recovery was 78, 69, and 59% for the incremen- tal levels of NH and 91, 68, 60 and 54% for the advancing 3 stages of plant maturity (DM%). Silage pH was increased with increasing silage dry matter and by the incremental amounts of added NH3. ‘Lactic and acetic acids were highest (P‘=.05) for the 30% dry matter silage and were not affected by NH3 or H20 level. Water insoluble nitrogen (WIN) levels of corn silage were.increased (P4<.05) at the highest dry matter (45%) and WIN levels were higher for all NH3 levels than for the control silage. It is theorized that the higher dry matter silages and NH both increase WIN or "true protein" content 3 of corn silage by preventing proteolysis. The third experiment (l-B) was designed to study the effect of urea (.5 and 1%) and anhydrous ammonia (.3, .6, and .9%) on silage fermentation and lactation parameters. The five silages were compared to control corn silage which was fed with either a 20% or a 9% crude protein (CP) concentrate. The NPN treated corn silages were also fed with 9% CP concen- trate. .All concentrates were fed at .4 kg/lkg daily milk. Thirty-five cows were blocked according to production into five groups. Cows from each block were randomly assigned to one of the seven different treatment groups for a 10-week feeding Ronald Lewis Boman trial. Water insoluble nitrogen tended to be higher (P—<.lO) for the .6% NH treated silage. Lactic acid was higher for 3 all NPN silage treatments compared to control. Milk yield was maintained at higher (P<=.05) levels for the cows on the positive than negative control ration (20% gs. 9% CP conc) while cows fed NPN treated silages had intermediate yields. Yields of 4% fat-corrected milk (FCM) were not different but cows receiving the negative control ration tended to eat less silage dry matter and to give less 4% FCM. Ruminal VFA levels were highest for cows receiving the positive control and the .6% NH3 rations. Blood urea N levels and daily yield of milk protein were highest for cows fed the positive control and the two highest levels of NPN. The fourth experiment (2-B) was designed to compare the effects of ammonia and urea additions to: l) freshly chopped corn silage prior to ensiling; or 2) fermented con— trol corn silage prior to feeding. Eight rumen fistulated Holstein steers were used in two 4 X 4 Latin squares. Diges— tibility of dry matter and nitrogen balance was lower for those silages to which NPN was added prior to ensiling. Ru- men liquor VFA concentrations and pH were unchanged. Rumin-_ al NH3 levels were lower (P<<.05) for NPN additions at ensile ing. Water insoluble N was higher (P<<.05) for NH3 added at ensiling but there were no discernable advantages manifest in this trial. DEDICATION To Rosella and Our Children: Robert Douglas Deborah Diana Paul Thomas ii ACKNOWLEDGEMENTS Sincere appreciation is extended to my advisor, Dr. John T. Huber for his guidance, encouragement and direction and many helpful suggestions during my association with Michigan State University. I thank the members of my guidance committee, Drs. Bergen, Cook and Gill for their appraisal of this dissertation. Also, I express my gratitude to Judy Ball and Becky Winters for their help in the laboratory and at the research barns, respectively. Most of all, I'll be eternally grateful to my angel wife for her encouragement to perservere and for typing this thesis. We are indebted to our children for making our lives full and rewarding. iii LIST OF TABLES . . . LIST OF FIGURES . . INTRODUCTION . . . . LITERATURE REVIEW . TABLE OF CONTENTS Importance of Corn Historical Aspects Harvested of Corn Silage Fermentation of Corn Silage as Silage Degradation of Carbohydrates . Degradation of Protein . Corn Silage Maturity . Dry matter harvested per hectare Ensiling losses Voluntary silage dry matter intake Silage dry matter digestibility . Milk production . Non-Protein-Nitrogen Additives to Corn Silage Urea treatment of corn silage . Ammonia treatment of corn silage PART A. NITROGEN FRACTIONS, PH, DRY MATTER AND ORGANIC Page vi ACIDS OF N-P-N, MINERAL AND DISACCHARIDE TREATED CORN S I LAGE O O O C 0 MATERIALS AND METHODS Experiment 1. Experiment 2. RESULTS AND DISCUSSION Experiment 1. Experiment 2. SUMMARY AND CONCLUSIONS iv Pilot Silo (1972-73). Pilot Silo (1973-74). Fermentation Fermentation 34 35 35 40 43 43 85 101 Page PART B. LACTATION AND METABOLISM TRIALS WITH NPN- TREATED CORN S I LAGES . C C O C O O C O C C O O O C O l 0 4 MATERIALS AND METHODS . . . . . . . . . . . . . . . 105 Experiment 1. Lactation Trial . . . . . . . . 105 Experiment 2. Metabolism Trial . . . . . . . . 108 RESULTS AND DISCUSSION . . . . . . . . . . . . . . . llO Experiment 1. . . . . . . . . . . . . . . . . . 110 Experiment 2. . . . . . . . . . . . . . . . . . 118 SUMMARY AND CONCLUSIONS . . . . . . . . . . . . . . 126 APPENDICES . . . . . . . . . . . . . . . . . . . . . . . 128 BIBLIOGRAPHY O O O O O O O O O O O O O O O O O O O O O O 135 TABLE 10 ll 12 l3 14 LIST OF TABLES Corn silage maturity (%DM) gs. voluntary silage intake by lactating dairy cows . . . . . . . . . . Continued . . . . . . . . . . . . . . . . . . . . Description of pilot silo treatment combinations . Statistical organization of parameters from Experiment 1 Part A O O O O O O O O O O O O O O 0 Effect of source and level of nitrogen and days of fermentation on temperature ('C) of corn silage. Effect of source and level of nitrogen and days of fermentation on pH of corn silage. . . . . . . . Effect of source and level of nitrogen and days of fermentation on lactic acid of corn silage . . . . Effect of source and level of nitrogen and days of fermentation on acetic acid of corn silage. . . . Effect of source and level of nitrogen and days of fermentation on total organic acids. . . . . . . . Effect of source and level of nitrogen and days of fermentation on dry matter content of corn silage Effect of source and level of nitrogen fermentation on total nitrogen of corn Effect of source and level of nitrogen fermentation on total soluble nitrogen Silage O I O O O O O O O O I O O O O I Effect of source and level of nitrogen and days of silage. . . and days of of corn and days of fermentation on water insoluble nitrogen. . . . . Corn silage temperature (°C) main effects during .fermentation . . . . . . . . . . . . . Effect of nitrogen source, additive, and day of fermentation on pH of corn silage . . vi Page 23 24 36 39 44 46 48 50 52 54 55 57 59 61 62 TABLE 14 15 15 16 16 l7 17 18 18 19 19 20 20 21 21 22 23 24 25 Page Continued . . . . . . . . . . . . . . . . . . . . 63 Effect of nitrogen source, additive, and day of fermentation on lactic acid content of corn silage 66 Continued . . . . . . . . . . . . . . . . . . . . 67 Effect of nitrogen source, additive, and day of fermentation on acetic acid content of corn silage 69 continued 0 O O O O O C O O O O O O O O O O O O O 70 Effect of nitrogen source, additive, and day of fermentation on total organic acid content of corn Silage O O O O O O O O O O O O O O O O O C O O O O 72 continued 0 O O O O O O O O O O O O O O O O O O O 73 Effect of nitrogen source, additive, and day of fermentation on dry matter content of corn silage 75 continued 0 O O O O O O O O O O I O O O O O O O O 76 Effect of source of nitrogen, additive, and day of fermentation on total nitrogen content of corn Silage O O O O O O O O O I O O O O O O O O O O O O 77 continued O O O O O O O O O O O O O O O O O O O O 78 Effect of nitrogen source, additive, and day of fermentation on total soluble nitrogen content of corn silage . . . . . . . . . . . . . . . . . . . 80 continued 0 O O I O O I O O O O O O O O 0 O O O O 81 Effect of nitrogen source, additive, and day of fermentation on water insoluble nitrogen content of corn silage . . . . . . . . . . . . . . . . . . 83 continued 0 O O O O O O O O O O O O O O O O O O O 84 Ammonia treated corn silage pH after 40 days fermentation . . . . . . . . . . . . . . . . . . . 86 Lactic acid of ammonia treated corn silage after 40 days fermentation . . . . . . . . . . . . . . . 88 Acetic acid of ammonia treated corn silage after 40 days fermentation . . . . . . . . . . . . . . . 90 Total organic acids of ammonia treated corn silage after 40 days fermentation . . . . . . . . . 92 vii TABLE 26 27 28 29 30 31 32 33 34 35 36 37 38 Page Dry matter content of ammonia treated corn silage after 40 days fermentation . . . . . . . . . . . 93 Total nitrogen of ammonia treated corn silage after 40 days fermentation . . . . . . . . . . . . 95 Total soluble nitrogen of ammonia treated corn silage after 40 days fermentation . . . . . . . . 98 Water insoluble nitrogen of ammonia treated corn silage after 40 days fermentation . . . . . . . . 100 Composition of concentrates and description of rations fed to lactating cows . . . . . . . . . . 106 Mineral supplement for Holstein steers fed NPN treated corn silage . . . . . . . . . . . . . . . 109 Chemical composition of corn silages fed in lactation trial . . . . . . . . . . . . . . . . . 111 Milk and milk constituent yield and body weight changes of cows fed urea and ammonia treated corn Silages O O O O O O O I C O O O O I O O O O I O O 112 Intake of dry matter and crude protein equivalent as influenced by NPN treatment of corn silage . . 114 Effect of urea and ammonia additions to corn silage on rumen and blood parameters. . . . . . . 116 Chemical composition of corn silages fed to fistu- lated steers (two 4 X 4 latin squares). . . . . . 119 Intake, digestibility, and nitrogen balance ob- tained from fistulated steers fed corn silage treated at ensiling or at feeding with either ammonia or urea . . . . . . . . . . . . . . . . . 121 Rumen liquor and blood plasma parameters of fis- tulated steers fed corn silage treated at ensiling or at feeding with either ammonia or urea . . . . 123 viii APPENDIX TABLE 1 Effect of source of nitrogen, disaccharide or mineral additive and day of fermentation on temperature ('C) of corn silage. . . . . . . . Continued . . . . . . . . . . . . . . . . . . Effect of CaCO plus sucrose or lactose and three sources 8f nitrogen on pH and lactic acid content of corn silage. . . . . . . . . . Effect of CaCO plus sucrose or lactose and three sources 8f nitrogen on acetic and total organic acid content of corn silage. . . . . . Effect of CaCO plus sucrose or lactose and three nitrogen sources on dry matter percent and total nitrogen content of corn silage. . . Effect of CaCO plus sucrose or lactose and three nitrogen sources on total soluble and water insoluble nitrogen content of corn silage . . . . . . . . . . . . . . . . . . . . Percent ammonia recovery as affected by silage dry matter and levels of added NH3 and H20 . . ix Page 128 129 130 131 132 133 134 LIST OF FIGURES FIGURE Page 1 Effect of maturity of corn plant on total dry matter accumulation . . . . . . . . . . . . . . . . l8 2 Silage dry matter intake as affected by corn silage maturity . . . . . . . . . . . . . . . . . . 25 3 Anhydrous ammonia and water mixing apparatus . . . 41 4 Effect of source and level of nitrogen upon lactic and acetic acids after 40 days of fermentation. . . 51 INTRODUCTION Corn will produce more digestible nutrients per hec- tare than any other food crop. Harvesting the entire corn plant as silage, instead of only for grain, nearly doubles the nutrient yield for ruminant feeding. Green-chopped corn ensiles remarkably well due to a high carbohydrate content which yields substantial amounts of organic acids upon fer— mentation. Corn silage is a highly palatable, concentrated forage of consistently high digestibility. Corn silage is an excellent energy source for rumi- nants but it is notariously low in crude protein content (8% of dry matter). Corn silage rations must be supplemented with either expensive plant protein or a source of non-pro- tein nitrogen (NPN). Urea has traditionally been the NPN supplement for increasing crude protein content of corn si- lage. Anhydrous ammonia is cheaper than urea and not only augments crude protein but also has been shown to increase the water-insoluble or "true protein" content of corn silage. Therefore, the objectives of this study were: (1) To evaluate urea and anhydrous ammonia alone or with mineral buffers and disaccharides as corn silage fermen- tation ammendments: (2) To compare recovery of anhydrous ammonia at vary- ing stages of corn silage maturity and follow fermentation parameters; (3) To evaluate urea and ammonia treated corn silage with minimal plant protein supplementation as a feed for lac- tating dairy cows; and (4) To determine nitrogen balance and digestibility of corn silage treated with urea or ammonia at ensiling and just prior to feeding. L I TERATURE REVI EW Importance of Corn Harvested as Silage Corn (Zea mays L.) is grown within a wide climatic range. It is grown from 58 north latitude in Canada and the USSR to 40 south in South America, and from below sea level in the Caspian Plain to 3,600 m and beyond in parts of the Andes. Despite this adaptability to vastly different environ— mental conditions, a minimum amount of moisture must be avail- able and temperatures must be above freezing during the grow- ing season. Corn is a warm-weather crop requiring consider- able warmth after tasseling. Once it is above ground it will tolerate only very brief and light frosts (Jenkins, 1941). Temperate areas, specifically the USA Corn Belt, the La Plata corn belt of Argentina, the Garonne Basin of France, Italy's Po Valley, and the Hungarian and Walachian Basin, produce three-fourths of the world's corn and are considered to have almost ideal climatic and soil conditions for the crop. Summer temperature should be about 24° C, with warm nights (average 14' C), and rainfall should be abundant, from 460 to 600 mm during the growing period (Van Royen, 1954). Corn will produce more digestible nutrients per unit of land surface where it is well adapted, than any other food crop that can be grown: Sorphum is a close second. Both have high levels of net photosynthesis with a minimum of energy loss through photorespiration (Wittwer, 1974). 4 Corn uses 56% less water per unit of dry matter produced than alfalfa (Coppock, 1969). Green-chopped corn ensiles remarkably well due to a high carbohydrate content which yields substantial amounts of organic acids upon fermenta- tion. Corn silage is a palatable, concentrated forage of consistently high digestibility (65—75% of the dry matter). Corn as silage is harvested but once during the growing sea- son, and lends itself to mechanical harvesting, storing, and feeding. Corn silage is the most important silage crop in Michigan with over four million metric tons produced in 1973 (Mich. Ag. Stats., 1974) which was 57% greater than 1959 due to 25% increases in both yield per hectare and total hectares harvested. US corn silage production for 1973 (USDA Ag. Stats., 1974) was 100 million metric tons with increased pro— duction trends similar to Michigan for the last 14 years (USDA Ag. Stats., 1972). The state of Wisconsin alone pro- duces 10 million metric tons and with the seven other North- central states accounts for nearly one-half the total US corn silage production (USDA Ag. Stats., 1974). Corn harvested for all purposes (approx. 25 million hectares) in 1969 re- presented 22.1% of all harvested US cropland and only 12% of this was harvested as silage (USDC Census of Ag., 1969). When harvested as silage instead of grain the total dry mat- ter for ruminant feeding is nearly doubled. It would appear that this idea ought to be actively promulgated among dairy- men and cattlemen. The cultural practices of sod-seeding 5 and minimum tillage should permit corn to be grown on land which, because of inclined terrain, has heretofore been used for less productive crops. Historical Aspects of Corn Silage Coppock and Stone (1968) reviewed the literature and credited the Egyptians and Greeks for having stored grain in pits or underground trenches. Johnston (1843) presented as worthy of acceptance a German method for harvesting and stor- ing green fodder by packing the direct-cut material into trenches which are then covered with boards and earth to fa- cilitate sealing. Reihlen of Germany was credited (Miles 1918) with being the first to use a silo to preserve the whole corn plant. Goffart (1877), of Burtin, France having gained experience with silage preservation for 20 years was the first to describe in practical terms in 1873 the impor- tant aspects of making corn silage successfully. He recom- mended that the length of out be one cm and that bricks or stone be placed on top of the silage to aid in packing and exclusion of air. Among the first to preserve corn as silage in the United States were Miles of Illinois in 1875 and Morris of Maryland in 1976 (Miles, 1918). By 1882 a USDA special re— port (Nesbit, 1882) summarized the experience of 91 respon— dents who were then using corn silage. Corn silage has been fed to dairy cattle at Michigan State University since 1881, but research in this area did not start until the introduc— 6 tion of hybrid corn in 1940 (Huffman, 1960). The late C.F. Huffman deserves much acclaim for his pioneering investiga- tions of corn silage during the 1950's from which he attest— ed to the abundant yield of total digestible nutrients per hectare, to the milk-stimulating capacity for lactating cows, and be strongly suggested that "corn silage should not be considered a true roughage, but a mixture of roughage and grain" (Huffman 1954a and b, 1956, 1959 and 1960). Fermentation of Corn Silage One of the first observations of production of or- ganic acids in corn silage was by Brandeau who analyzed the corn silage of Goffart. The volatile acid was designated acetic acid and the non-volatile, lactic acid (as reported by Annett and Russell, 1908). Analysis of the whole corn plant before and after ensiling led Annette and Russell (1908) to conclude that the major changes which take place during fermentation are: disappearance of most of the sugars; production of carbon dioxide and a number of organic acids; reduction in protein nitrogen by one—half and a concomitant increase in non—protein nitrogen. However, there was little change in fiber content. Subsequently, Russell (1908) iden- tified in corn silage the volatile fatty acids (formic, ace- tic, and butyric) and the non-volatile acids (lactic, malic, and succinic) plus a number of amino acids and purine bases. The five aliphatic acids, formic through valeric, were quantitatively identified by Dox and Neidig (1912), 7 with acetic comprising about 90 percent of the total. Pro- pionic acid was second in importance and butyric acid was found only in samples characterized by some spoilage. One year later the same workers (Dox and Neidig, 1913) reported that lactic acid was normally present in corn silage at 1e- vels 25% higher than the volatile acids. They further char- acterized the lactic acid of corn silage as an optically in- active racemic mixture. Neidig (1914) took samples over a two week period and reported the concentration of both vola— tile and non-volatile acid reached a plateau in about eight to ten days, which indicated that fermentation was essenti- ally complete after two weeks. The amount of acid produced was indirectly related to maturity, owing to the higher sug- ar and moisture content of the immature corn plant. Barnett (1954) outlines the changes during silage fermentation as a four or possibly five—phase process: Phase 1. The continued respiration of the plant cells results in the production of C02, the utilization of simple carbohydrates, and the evolution of heat; ' Phase 2. Acetic acid is produced in small quanti- ties by organisms of the coliform group (This phase is short and merges into the third phase); ‘Phase 3. Lactic acid organisms, lacto-bacilli and streptococci, supported by adequate carbohydrate, initiate a lactic acid fermentation; Phase 4. Quiescence in the silage mass during which lactic acid production passes its peak and remains constant 8 at 1 to 1.5% of the fresh weight, with a constant pH less than 4.2. These four phases occur over a three-week period with the first three being complete after three days. Insufficient lactic acid production or incorporation of air into the mass may cause development of the fifth phase; Phase 5. Butyric acid-producing organisms attack both residual soluble carbohydrates and the lactic acid which has been formed. In extreme cases, there may be deami- nation of amino acids with the formation of higher volatile fatty acids and ammonia as well as decarboxylation leading to the formation of amines and carbon dioxide. Peterson gt 31; (1925) noted that the first chemical changes incident to ensiling corn were that after four to five hours oxygen disappeared and for about 48 hours carbon dioxide rapidly increased. They observed the presence of large numbers of lactic acid-producing bacteria, as fermen- tation products appeared in 25 to 48 hours after ensiling. Utilizing sterilized corn inoculated with bacteria they de- monstrated that corn silage could be made without the bene- fit of plant cell respiration. Their conclusion was that bacteria are the chief agents involved in the production of silage acids from the sugar and starches of the ensiled plant. A similar conclusion regarding the production of acids was made by Hunter (1921), but he felt that the forma- tion of ammonia was due to both plant exzymes and bacteria. A complete review of the microbiology of silage is presented by Kempton (1958) who found that less than .1% of 9 the bacteria on the crop at time of ensiling were capable of growing on lactobacillus selection medium. Degtadation of Carbohydrates Organic acids are formed due to the action of micro- organisms on the carbohydrates of the ensiled plant material (Hunter, 1921; Watson and Nash, 1960). This is considered the most salient feature of the ensiling process. Johnson gt El; (1966) reported decreases in corn plant soluble car- bohydrate ranging from 39 to 83% and concurrent conversion to lactic and acetic acids. Peterson gt El; (1925) observed that starch of the corn plant material decreased from 10 to 30% with ensiling. Iowa researchers (Dox and Neidig, 1912) also noted considerable degradation of starch, while others (Dexter gt glt_a959) showed no appreciable breakdown. Geasler (1970), using laboratory silos to evaluate fermentation parameters over a 10-week harvesting period with silage dry matter ranging from 22 to 48%, showed that as dry matter and/or maturity increased the lactic acid con- tent of corn silage was significantly (P-<.01) reduced from a high of 5.8% to a low of 2.2% of the dry matter. Acetic acid was also significantly (P‘<.Ol) reduced with advancing corn plant maturity. Soluble carbohydrate level followed that of the organic acids and was probably the reason for the decrease in organic acids. Other researchers have noted similar declines with advancing maturity of the corn plant (Gordon gt al., 1968; Johnson and McClure, 1968). 10 Degradation of Protein Plant protein breakdown and a consequent increase in water soluble NPN during ensiling is regarded as an in- evitable forfeiture. Various factors may alter the extent of proteolysis. Ordinarily proteolytic enzymes of plant cell origin are directly responsible for this hydrolysis (Barnett 1954; Watson and Nash 1960). Russell (1908) treat- ed corn silage with chloroform or toluene to arrest plant cell and micro-organism activity and attributed the result- ant proteolysis to plant "tryptic" enzymes. Hunter (1921) analyzed field pea and oat, corn, and corn plus soybean sil- ages and concluded that the bacteriological and chemical changes were similar for all silages. The field pea and oat silage ensiled in glass jars was subjected to either control treatment, 2% chloroform, or sterilization by heating and inoculation with silage juice. Chloroform treatment essen- tially halted organic acid production via microbial inhibi— tion but did not change the level of proteolysis ascribed to the plant enzymes. Sterilization of the silage mass and subsequent inoculation with silage juice teeming with charac- teristic silage bacteria resulted in normal organic acid production but proteolysis was arrested due to plant enzyme inhibition. Mabbit (1951) approached this question by ensil- ing timothy grown in a microbe free chamber. Chemical analy- sis after ensiling revealed the absence of organic acids, a fourfold increase in amino acid nitrogen, and an elevenfold increase in volatile bases. This effect on fermentation was ll attributed to the plant enzymes since bacteria were absent Watson and Nash (1960) conclude that protein degradation to amino acids is primarily the action of plant enzymes, but add that certain butyric acid bacterial enzymes may decom- pose plant protein of crops low in soluble carbohydrates during initial fermentation. Refermentation of silage, associated with putrefying changes when air is introduced into silage, elicits further bacterial degradation of amino acids to keto acids, amides, amines, carbon dioxide and am- monia (Barnett, 1954) Some loss of plant protein during ensiling is un- avoidable since the bacteria which produce the acid neces- sary for silage preservation require nitrogen for growth. In fact, nitrogen may have to be added to crOps which have a low content of natural protein. Cullison (1944) showed that a more rapid fermentation of sweet sorghum was acheived by adding 0.5% urea to the fresh material. The keeping quality, as measured by lower silage temperature and increas— ed titratable acidity, was also enhanced. Barnett (1954) suggests that chopping and crushing plants prior to ensiling induces earlier lactic acid fermentation which in some cases has increased the crude protein content of the resultant silage. The magnitude of proteolysis of ryegrass (Lolium perenne) silage, harvested just prior to head emergence and after seven days of ensiling, ranged from 18 to 29% depend- ing on the silage dry matter (Brady, 1965). Water soluble 12 NPN constituted from 37 to 47% of the total N after 133 days of ensiling. Hughes (1970) estimated that 20% of total N of fresh perennial ryegrass was NPN compared to a determined average value of 65% NPN for eleven samples taken 2-18 months after ensiling. Hawkins (1969) observed 54% of total N as soluble NPN in 22% DM alfalfa silage. The amount of sol- uble N decreased as silage dry matter was increased due to wilting. Crude protein of freshly chopped corn silage consists of only 13-15% NPN (Cash, 1972; Salas, 1971). Protein degra- dation to ammonia and other NPN compounds consequent to en- siling elevates NPN to 36-48% of total N (Bergen, Cash and Henderson 1974; Cash, 1972; Salas, 1971). Johnson gt gt; (1967) reported tungstic-acid—supernatant nitrogen nearly doubled during ensiling over a range of 20-46% dry matter while there was essentially no change when harvested at 55% dry matter. Proteolysis is extremely difficult to eliminate ex- cept with mineral acids. Watson and Nash (1960) credit A.I. Virtanen with having shown experimentally that neither plants nor the anaerobic microorganisms contain proteolytic enzymes capable of action below pH 4.0. Addition of hydro- chloric acid to clover silage to give a pH of 3.6 after four weeks resulted in soluble and ammonia nitrogen levels equiva- lent to freshly chopped material, while the non-acid control treatment magnified the respective nitrogen levels 3 and 15 times. Addition of hydrochloric acid to achieve a final pH 13 of 4.3 led to proteolysis intermediate between fresh mater- ial and control, while a final pH of 4.6 was similar to con- trol (Virtanen, 1933). Other mineral acids including sul- furic and phosphoric have been used alone and in combination with hydrochloric (Watson and Nash, 1960), but the corrosive nature of the mineral acids for men and equipment is a seri- ous problem which tends to limit their use (Owen, 1971). Organic acids have been used on a limited scale to inhibit proteolysis and enhance corn silage preservation. Huber gt gt; (1972) employed pilot silos (plastic bags in— side 200 liter metal barrels) to investigate additions of formic, acetic, propionic, and lactic acids to 24-28% DM corn silage. Formic acid markedly decreased silage lactic acid and NPN, while causing a concurrent increase in water insoluble nitrogen. All other acid treatments had a similar but less pronounced influence on silage nitrogen fractions. Feeding trials with dairy (Huber gt 21;! 1973b) and beef (Cash gt gtt, 1971) animals demonstrated no advantage in animal performance from .5 to .6% formic acid at ensiling to 31 to 39% DM corn silage, even though proteolysis and bacte- ria fermentation were reduced. Again (Huber gt 91;! 1973b) formic acid more effectively inhibited proteolysis and lac- tic acid production than either acetic or propionic. Huber (1971) demonstrated increased silage intake and greater milk production of 43% DM urea-treated corn silage when formic acid was added prior to ensiling at 1.5% of the dry matter. These animal responses were negatively related to the extent 14 of bacterial fermentation and silage proteolysis. A more attractive method of controlling proteolysis of corn silage would be the addition of NPN. Johnson gt gt; (1967) demonstrated that additions of urea and limestone, each at .5% of corn silage green weight, further decreased the percent of total N as tungstic-acid-precipitable nitro- gen (true protein nitrogen) when harvested at 27% dry matter and below, but increased the amount of true protein at dry matter levels of 34% and above. Coppock and Stone (1968) cite German and Russian workers who have shown that urea ad— ditions to corn silage at ensiling increased the true pro- tein and ammonia content when compared to control silage. 15N labeled urea at .6% of silage fresh weight Addition of increased true protein 22% more than in control corn silage. Approximately 30% of this increase in true protein was attri- 15N labeled buted to microbial synthesis of protein from urea. The remainder of the true protein increase was ascrib- ed to a sparing action of the urea since it appeared to re- duce proteolysis during silage fermentation. Another Russ- ian experiment cited by these same reviewers (COppock and Stone, 1968) demonstrated that .65% urea added to corn sil- age provided true protein values approximately 35% greater than control corn silage. Ammoniated corn silage also evokes higher true pro- tein levels than the same material ensiled without additives. Huber and Santana (1972) showed that compared to control corn silage, urea and an anhydrous ammonia-water mixture 15 elevated water-insoluble nitrogen (true protein) 34 and 49%, respectively. A subsequent investigation (Huber gt 21;! 1973c) revealed that urea, aqua ammonia, and an ammonia— molasses-mineral suspension all increased water-insoluble nitrogen 38, 45, and 54%, respectively, when compared to control corn silage. Other researchers have reported simi— lar increases in water-insoluble nitrogen when either urea or ammonia is added to corn silage at ensiling (Beattie, 1970; Cash, 1972). Bergen gt_gtt (1974) filled 4-1iter glass jars with either control or corn silage treated at 2.25% of green weight with an ammonia-molasses-mineral suspension (13.6% nitrogen). Buffered extracts from these laboratory silages were used as proteolytic enzyme sources. Proteolytic acti- vity (m equiv. nitrogen solubilized per 5 ml of incubation system per 420 minutes) of NPN treated silage was 50, 20, 42, and 56% lower than control silages on days 0, l, 2, and 5 respectively. This observation would imply that NPN spares corn plant protein from degradation. Corn Silage Maturity The most important single factor affecting digesti- ble nutrient yield per hectare and voluntary silage intake by dairy cattle is the stage of growth at which corn is har- vested for silage. Field and storage losses are affected by stage of maturity, but digestibility of dry matter bears little relation to stage of growth (Coppock & Stone, 1968). 16 Dry matter harvested per hectare Dry matter accumulation (average of adapted hybrids grown in central Iowa) as related to stage of growth, dry matter percent, and the relative proportion of plant parts is depicted in Figure 1 (Hanway, 1966). While this graphic representation is not universally applicable, it does point out that harvesting too early diminishes the total dry mat- ter yields. This reduction would be almost entirely due to less grain which in itself enhances silage energy value. The corn kernel at physiological maturity is 65 to 70% dry matter (Daynard and Duncan, 1969; Hanway, 1966) which, in effect, dries out the corn plant. Silage made from corn harvested at this stage of growth (35% dry matter) will not cause seepage problems in the silo and will be readily con- sumed by cattle. Physiological maturity of normally developed corn coincides with the formation of an abscission-type layer near the tip of the kernel. This closing layer (ranging in color from brown to black) reportedly forms within a 3-day period and is a useful indicator of cessation of nutrient deposition in the kernel coincident to maturation of the corn plant. Normal kernels should be obtained from the cen- tral portion of the ear on healthy green plants to most ac- curately characterize physiological maturity (Daynard and Duncan, 1969; Rench and Shaw, 1971; Daynard, 1972). This simple method has proven effective in Kentucky (Daynard and Duncan, 1969), Iowa (Rench and Shaw, 1971; Baker, 1971) and with early planted corn in Ontario, Canada (Daynard, 1972). 17 Dry matter content of normally developed corn kernels is ap- proximately 70% at completion of black layer formation. How- ever, this phenomenon also occurs subsequent to a deficit of available assimilate due to frost-damage of leaves, drought, desease, or a nutrient deficiency (Daynard and Duncan, 1969; Daynard, 1972) and therefore cannot always be relied upon to predict when to harvest corn for silage. Total dry matter content of the corn plant also re— flects the degree of physiological maturity. Descriptive terms for kernel development such as milk, dough, dent, or glaze while less objective than dry matter percent do, how- ever, assist in characterizing stage of maturity. The dry matter content of the whole corn plant at physiological ma- turity is 32 to 38% and the kernel is in a hard dent to glazed state and it is at this point that maximum yield of grain and silage dry matter is realized (Jorgensen and Crow- ley, 1972). The proximate composition of the corn plant changes with increasing maturity. Dry matter content of the total plant increases, but expressed as a percent of the total dry matter, there are decreases in crude protein and crude fiber while both ether extract and nitrogen free extract increase (Hooper, 1925; Stallcup gt gtt, 1964). Harvesting corn for silage before physiological ma- turity reduces potential nutrient yield. On the other hand, delaying harvest beyond physiological maturity augments field loss of leaves, ears, and in extreme cases the stalks and whole plant may be lost because of lodging. Byers and 20 Figure l. 100 90 4.) g 80 r-1 0.. .2 70 H (D 3 60 (U E 5 50 'U H B 40 O 4.) % 30 JJ :2 (1) 0 H (1) (3.. Source: 10 18 Effect of maturity of corn plant on total dry matter accumulation. ' I -All kernels fully dented I 100 (physiological maturity) ~ ~ 90 4.) tLate dough & early dent___§ _ 80 g H ' Q _Late milk & early dent_;> _ 70 ,5 LI 3 ~Blister & early milk_;, 1 60 -g E: _ a 50 5‘ COBS AND SILK P Q ~ 40 8 HUSK & EAR SHANK u — 3o 6 STALK AND TASSEL u C: ~ 20 § LEAK SHEATHS g 10 LEAVES l l l l I J 0 0 20 4o 60 80 100 110 120 Age of corn plant, days % Dry Matter 14 20 27 29 35 39 Maturity of corn plant Hanway, 1966 l9 Ormiston (1964) harvested late planted corn at 32% dry mat- ter and 45 days later at 55% dry matter. The last harvest yielded 11% less dry matter per hectare mainly due to plant lodging. USDA researchers (Gordon gt 21;! 1968) harvested corn silage in two successive years at the hard dough (26 and 30% DM) and seven to eight weeks later after full maturity and additional weathering (58 and 63% DM). Dry matter yield was 19 to 27% less when harvest was delayed 50 to 60 days. This loss in yield was attributed to plant lodging. Reduc- tion in dry matter yield of late harvested corn in both the Illinois (Byers and Ormiston, 1964) and the USDA (Gordon gt gtt, 1968) experiments should have been greater had their early harvested corn been physiologically mature. Huber gt El; (1968) harvested corn for silage at 30, 36, and 44% dry matter and noted dry matter yields of 10.4, 12.2, and 10.2 metric tons per hectare, respectively. The lower yield at the earliest harvest was attributed to the plant not having reached physiological maturity, while the reduced yield at. the last harvest was due primarily to field losses. South Dakota researchers (Owens gt gtt, 1968) showed three to five- fold greater field losses due to leaf and ear droppage and whole plant lodging when corn was harvested for silage at 62 compared to 38% dry matter. Geasler (1970) reported decreas- ing dry matter yields on three harvest dates with dry matter contents of 28, 48 and 60%. Obviously, peak yields were again missed. However, the subsequent year there were no yield differences for three harvest dates ranging in dry 20 matter percent from 31 to 43. Hoglund (1964) appraised field and harvest losses of corn harvested for silage to be only 4% when total plant dry matter is 30 to 35% at ensiling time. Ensilingilosses Seepage losses should be negligible to nonexistent if corn is harvested for silage at the point of maximum dry matter yield and physiological maturity. Gordon (1967) re- viewed seepage losses of grass and legume silages and conclu- ded that seepage loss was practically eliminated when dry matter content reaches 30 to 32%. Georgia researchers (Mil- ler and Clifton, 1965) report no dry matter lost as seepage from 38% DM corn silage. Seepage tends to be less in hori- zontal silos, because of less vertical pressure. However, in unsealed bunkers, leaching from rain and snow can increase seepage losses an additional eight to ten percentage units above that observed in sealed bunkers (Gordon, 1967). Sprague and Leparulo (1965) stored corn silage of 24 and 33% DM in 1.8 metric ton plastic silos and reported DM losses of 5.6 and 3.8%, respectively. After summarizing several studies, Hoglund (1964) concluded that 30 and 35% DM corn silage at ensiling lost 11 and 8%, respectively, of the DM in a concrete vertical silo, but only half that amount in a gas-tight vertical silo. Huber gt El; (1968) observed av- erage DM losses of 7.0, 6.4 and 15.1% for corn silage har- vested at 30, 36, and 44% DM and either ensiled as control or with .5% urea. This greater DM loss at the higher dry matter was attributed to less effective air exclusion which 21 caused extended heating and aerobic oxidation. Byers and Ormiston (1964) suggest that fine chopping and packing to exclude air are more critical with 55% DM corn silage. Spoilage losses are directly proportional to the a- mount of air permeating the silage mass and the extent of surface exposure to air and weather (Gordon, 1967). Gordon gt gt; (1968) reported spoiled silage of 2.3 and 4.3% for corn silage stored in gas-tight silos at 28 and 60% DM, re- spectively. Gaseous losses are also increased by increasing permeability of the silage structure and silage mass to air. This is particularly true in forages of low moisture content, which are less dense and readily oxidized (Gordon, 1967). Voluntaty silage drytmatter intake The interrelationship of corn plant maturity (% DM) at harvest and voluntary silage dry matter intake by lactat- ing dairy cows from 19 experimental comparisons is summarized in Table 1. Pertinent details such as number of cows, length of experiment, and amount of feed in addition to silage for each comparison are also included. The first nine compari- sons (Bechdel, 1926; Bryant gt gtt, 1966; Buck gt 21;! 1969; Huber gt gtt, 1965; and Owens gt gtt, 1968) show increased dry matter intake with increasing silage dry matter content. The response was greatest when comparing silages harvested in the 20% DM range with those harvested near 32 (Bechdel, 1926; and Bryant gt gtt, 1966). Gas tight silos used in two of these first nine comparisons resulted in four to eight percent greater dry matter intake with advancing maturity 22 when comparing silages of 38 to 39% DM with those of 61 to 64; however, the grinding of the latter silage in a hammer- mill may have accounted for this increased intake (Owens gt 21;! 1968). The remaining ten comparisons either showed an in— crease followed by a decrease of dry matter intake over the range of silage DM percentage studied (Montgomery gt gtt, 1974; Huber 22.31;! 1968; and Polan gt 21;! 1968) or a slight (Huber gt 21;! 19730; Gordon gt 21;! 1968; Huber, 1971) to a significant (Byers and Ormiston, 1966; Gordon gt glt, 1968; and Huber, 1971) decrease in dry matter intake with advancing maturity. Data on intake and stage of maturity from Table l (excluding the two South Dakota gas tight silo comparisons of Owens gt 21;! 1968) were subjected to covariance analysis with experimental trials serving as treatments and dry matter percent at harvest as the polynomial covariate. The multiple regression coefficients thus derived were used in the equa- tion Y = B0 + le + B2X2 + 33x3 to best estimate silage dry matter intake (Y) over the dry matter (X) range of 15 to 63%. The polynomial regression curve in Figure 2 indicates maximum dry matter intake corresponding to corn silage maturity at 38% DM. However, intake would not differ appreciably within the silage dry matter range of 33 to 43%. Depressed DM intake associated with silage dry matter percent above 43 is probably not due to maturity per gg, but to an inability to exclude air from the silage mass. High DM 23 Table 1. Corn silage maturity (%DM) 2g. voluntary silage intake by lactating dairy cows DM intake % DM %of BW 1. 15 .64 Bechdel, 1926. 12 to 16 cows/trt for 56 23 .72 to 84 days. Corn silage + conc. @ 1:4 + 4 27 .78 kg hay/day. 2. 19 .62 Bechdel, 1926. 8 to 16 cows/trt for 84 21 .71 days. Corn silage + conc. @ 1:4 + 3.2 kg 31 1.04 hay/day. 3. 22 1.51 Bryant gt al., 1966. 12 cows/trt for 105 32 2.38 days. Corn silage + 1.8 kg CSM or conc. @ 1:3 and 2.3 kg bay. 4. 22 1.58 Buck gt al., 1969. 16 cows, (4 X 4 latin 30 1.73 sq. with 5-wk periods). Corn silage + 34 1.85 4.2 kg conc./day. 46 1.86 5. 25 1.95 Huber gt al., 1965. 6 cows/trt each of 2 30 2.13 years. Corn silage + SBM @ 1:7.6 for 33 2.31 last 8 wks of 140 days in 1962 & SBM @l:9.6 for first 11 wks of 150 days in 1963. 6. 25 1.81 Huber gt al., 1965. 6 cows/trt each of 2 30 1.90 years. Corn silage + conc. @ 1:3.5 for 33 2.00 first 12 wk of 140 days in 1962 and last 4 wk of 105 days in 1963. 7. 33 2.04 Buck gt al., 1969. 16 cows (4 X 4 latin 39 2.12 sq. with 5-wk periods). Corn silage + 4.6 kg conc./day. Each silage normal-cut and recut. 8. 39 .93 Owens gt al., 1968. Gas tight silos. Sil- 61 .97 age ground in a hammermill. 10 cows for 119 days. Corn silage + 4.5 kg hay/day + conc. @ 1:2.5. 9 38 1.78 Owens gt al., 1968. Gas tight silos. Sil- 64 1.92 age ground in a hammermill. 10 cows/trt in double reversal trial (5-wk periods). Corn silage + conc. @ 1:3. 10. 26 1.31 Montgomery gt al., 1974. 6 Jersey cows/trt 34 1.51 in a switchback trial (5-wk periods) each 42 1.50 of 2 years. 8 cows/trt for 12 wks for 3rd year. Corn silage + conc. @ 1:3 all years. 24 Table 1. Continued. DM intake % DM % of BW 11. 30 2.02 Huber gt al., 1968. 18 cows/trt for 60 36 2.04 days. Corn silage + conc. @ 1:2.5 above 44 1.88 11.4 kg milk/day. One-third of cows from each group received urea-treated silage. 12. 32: 2.00 Polan gt al.,a1968. 6 cows/trt for 63 days. 37 2.20 Corn silage ( .85 or .6% urea) + conc. 44 2.10 @ 1:3. 13. 37 1.06 Byers and Ormiston, 1966. ll cows/trt for 44 .84 56 days. Corn silage + conc. @ 1:3 + hay 52 .81 @ 1% of body weight. 14. 26 1.54 Gordon gt al., 1968. Gas tight silos. 7 58 1.44 cows/trt for 50-day gg lib. trial. Corn silage 3g lib. + conc. @ 1:2.8 + hay @ .5% of body weight. 15. 30 1.02 Gordon gt al., 1968. Gas tight silos. 10 63 .79 cows/trt for 110 days. Corn silage + conc. @ 1:2.4 or 1:3.6 + hay @ .5% of body weight. Silages fed in summer with a tendency to heat. 16. 36 1.70 Huber, 1971. 6 cows/trt for 70 days. Corn 52 1.20 silage (urea .5 or .75%, fresh basis) + conc. @ 1:3. 17. 28 1.50 Huber, 1971. 6 cows/trt for 56 days. Corn 43 1.38 silage + conc. @ 1:3. 18. 31 1.25 Huber gt al., 1973c. 8 cows/trt for 84 days. 42 1.24 Corn silage (2 or 2.5% NH -soln.) + 2.2 kg hay/day + conc. @ 1:3. 4 25 mmmawm auoo mo uwuuma hup ucwoumm mm Hm mm hm mm mam av 3 me ma av mm Em mm mmam am pm mm mm am m.” D m.” w. h. m. m. o.H H.H N.H m.H v.H m.H m.H b.H m.H m.H o.N H.m mxmhaaoooo.+ N.N xmmmmoo.lthma.+MFhm.lnM m.N v.m Q mmufiusume mmmafim :uoo mo pmuowmmm mm wxmucfi uwuums mun wmmHflm .N musmflm .Amcfla cofimmwummu HmfiEocmHom EOum pwuufleo m a m mamfluuv H manna ca mamfluu mum mala muwDEDZm (qubram Apoq go quaoxad) axequr Jaqqem Kip 362113 26 corn silage in the South Dakota study (Owens gt glt, 1968) was ground in a hammermill (2.5 to 3.8 cm screen) and ensiled in gas tight silos. Both operations would tend to exclude air resulting in a cooler more desirable fermentation thus improving intake. Silage dry matter digestibility Digestibility of corn silage dry matter is not appre- ciably nor consistently altered by maturity of the corn plant. Various researchers have reported modest declines in DM di— gestibility with advancing maturity (Noller gt git, 1963; Owens gt 21;! 1968), others noted no change (Buck gt 91;! 1969; Huber §£,§l;r 1965; Perry gt 21;! 1968; and Johnson and McClure, 1968), while others observed modest increases with advancing maturity from 20 to 30 (Bryant 23.21;! 1966; Buck gt El;' 1969;) and from 20 to 40% dry matter (Buck gt gtt, 1969). Mean dry matter digestibilities taken from nine di- gestion trials by seven groups of researchers (Bryant gt gtt, 1966; Buck gt 21;! 1969; Huber gt_gtt, 1965; Johnson and McClure, 1968; Owens gt gtt, 1968; Perry gt 31;! 1968; and Sprague and Leparulo, 1965) were subjected to covariance ana- lysis similar to the dry matter intake data. There were 42 individual dry matter digestibility (Y) observations ranging from 22 to 80% dry matter (X) (avg. 4.7 observations per ex- perimental trial). A simple linear regression, Y=69.39 - .00136x, failed to have significant slope, i.e. the effect of maturity on dry matter (DM) digestibility was not significant. 27 Crude protein digestibility of the corn silage dry matter tended to decline an average of .16 percentage unit for each percentage unit increase in silage dry matter over a range of 21 to 71% (Bryant 23.21;: 1966; Johnson and McClure, 1968; Owens gt al., 1968; and Sprague and Leparulo, 1965). Milk production Milk yield of cows fed corn silage is either positive- ly correlated with (Bechdel, 1926; Bryant gt gtt, 1966; Buck gt gtt, 1969; Byers and Ormiston, 1966; Huber gt 21;! 1965; Huber, 1971; Owens gt glt, 1968; Polan gt gtt, 1968) or not significantly affected by silage dry matter intake (Gordon gt gtt, 1968; Huber gt gtt, 1968; Huber gt gtt, 1973c; Mont- gomery, gt gtt, 1974). The polynomial regression curve of estimated silage dry matter intake in Figure 2 also approxi- mates the milk production response to silage maturity (DM%). The stimulus being greatest up to 33% DM (Bechdel, 1926; Bryant gt glt, 1966; Buck gt_g1t, 1969; Huber gt 21;! 1965; Montgomery gthtt, 1974), then stable from 33 to 42 (Buck gt 21;: 1969; Montgomery ££,éi;v 1974; Polan gt git, 1968; Huber gt git, 1973c) and either increasing slightly (Owens gt 21;} 1968) or slowly decreasing (Byers and Ormiston, 1966: Gordon gt gtt, 1968; Huber gt glt, 1968; Huber, 1971) beyond 42% dry matter. Non-Protein-Nitrogen Additives to Corn silage Corn silage is an excellent source of energy for dairy and beef animals but crude protein (8% of dry weight) is 28 inadequate for most productive purposes. Ruminants can util- ize NPN via microbial protein synthesis and corn silage is a convenient and uniform carrier for such additives. Distribu- tion of silage intake over a greater part of the day compared to concentrate intake should permit more efficient utiliza- tion of NPN when added to corn silage as compared to addition to the concentrate. Urea treatment of corn silage Urea is the most widely used and accepted NPN source for addition to corn silage. Uniform distribution of urea at from .5 to 1% over the top of the load of silage before un— loading or by metering onto silage at the blower should in- crease crude protein on a dry basis by four to eight percen— tage units. Woodward and Shepherd (1944) and Wise 2£.El; (1944) were among the first to add urea to corn silage in this coun- try. Addition of .5% urea to 25 to 30% DM corn silage reduc- ed voluntary intake but did not alter milk production. The latter researchers (Wise gt_gtt, 1944) successfully fed two cows a diet of 1% urea treated corn silage in substantial a- mounts for 60 days. Conrad and Hibbs (1961) showed that .7% urea treated corn silage was unsatisfactory as the only feed for lactating cows. Feed intake, nitrogen utilization, and milk production were lower than comparable cows on alfalfa- hay and grain. However, this study was of short duration (3 wk), the corn silage of low DM% (26.6) with accompanying seepage, and milk production was low for both groups of cows. 29 Even so, it was concluded that corn silage contained insuffi- cient energy to support NPN utilization in dairy cows and that urea should be supplemented via concentrate feeding. These same researchers, three years later (Conrad and Hibbs, 1964), suggested limiting urea-treatment of corn silage at .35 to .5%, and subsequently admitted (Conrad and Hibbs, 1967) that 32% DM corn silage ensiled with 1% urea provided suffi- cient supplemental nitrogen to maintain daily milk production at an average of 22 kg (highest 34 kg) during the third to sixth months of lactation provided that 50% of the ration DM came from cereal grains. Klosterman gt gt; (1965 and 1970) also at Ohio have reached similar conclusions for finishing beef cattle. Schmutz gt gt; (1969) treated 29% DM corn silage with 0, .5, or .75% urea and compared these three silages as the only roughages for lactating cows. Rations were made isocal- oric and isonitrogenous by additions of ground shelled corn and soybean meal. DM intake was reduced by the highest level of urea but milk production responses were similar for all treatments. Van Horn gt El; (1967, 1969) found no intake or milk production differences when 33% DM corn silage was un- treated or treated with .5% urea at ensiling, even though the latter was fed with or without urea in the concentrate. Knott gt gt; (1972) compared corn silage with .5% urea added at ensiling to non-urea silage both fed with 13% crude protein concentrates containing either 0 or 1.5% urea. Intake of dry matter and persistency of milk production were 30 both enhanced by urea in the corn silage. Huber and Thomas (1971) compared 35% DM corn silages treated at ensiling with 0, .5, or .75% urea. Concentrates containing 8, 12, or 18% preformed crude protein were also fed with certain of the silages. Milk production and intake were lowest (p<:.05) for cows receiving no supplemental nitro- gen. Addition of .5% urea to corn silage resulted in a 4.5 kg increase in daily milk yields when compared to the nega- tive control group. The highest and most economical milk yields were noted for the ration in which approximately 50% of the supplemental N came from .5% urea added to the corn silage and the remainder from concentrate with 12% crude pro- tein. Polan gt gtt (1968) added between .5 and .85% urea to corn silage which ranged in dry matter from 32 to 44%. Con- centrates contained protein from natural sources. Milk pro- duction and silage intake were not significantly altered by urea-treatment. Cows receiving .85% urea-treated corn silage tended to have lowered silage intakes and milk production; however, silage dry matter for this treatment was lowest (32%) and nearly 40% of the total nitrogen intake was from NPN. Ammonia treatment of corn silage Anhydrous ammonia is a less expensive source of nitro- gen than urea, and thus has appeal as an alternative silage NPN additive. Polish researchers (Abgarowicz gt gtt, 1963) treated corn silage of 17% dry matter with .5% urea, .5% di- ammonium sulfate and/or ammonia water (isonitrogenous with .5% 31 urea). Silages were stored for four months in cylindrical basalt vessels of 62 liter capacity. Silage quality was sub- jectively scored organoleptically and structurally. The ammonia water treated silage was rated inferior to the other silages, but all silages were considered to be representative of good silage. Huber and Santana (1972) treated 35% DM corn silage with anhydrous ammonia dissolved in water (equivalent to .28 and 3% of NH3 and H20 on a fresh silage basis, respectively). Water and liquid NH3 hoses were connected by means of a "Y" tube and the above solution was delivered to the silo blower. Comparable silage was either ensiled with .5% urea or no add— itive (control). Heifers weighing approximately 420 kg (10/ silage) were offered either control or ammonia treated corn silage 3g libitum for 16 days. Crude protein was increased (from 8.8 to 11.5% of silage DM) by ammonia treatment as was daily silage DM intake (2.08 2g. 2.33% of BW). Lactating cows, fed concentrates containing preformed protein at one kg per three kg milk and silages gg libitum, consumed control, urea-treated, and ammonia-treated silages equally well when offered iso-nitrogenous rations. Persistency of lactation was similar for all treatments. Corn silage (30% DM) treated with 1% aqua ammonia (22% N) prior to ensiling was compared in a 12-wk lactation experiment with silages treated with either .75% urea or no additive. There were no differences in silage intake or milk production (Huber and Santana, 1972). In an experiment by Huber gt al. (1973c), factors 32 influencing utilization of ammonia-treated corn silage were studied in two trials. In trial 1, aqua ammonia, a commer- cial ammonia-mineral-molasses mixture (ProSil) or urea was added to 32% DM corn silage prior to ensiling. The ammonia- ted silage resulted in greater (P<:.025) milk production but there were no differences in silage DM intake. ProSil addi- tions to 31 and 42% DM corn silage gave similar results. In the second trial, ProSil and urea treated silages were com- pared at low (29-30%) and high (44-53%) dry matter. Milk production among NPN treatments favored the low dry matter silage (P<:.025). Cows fed ProSil-treated corn silage out— yielded those fed urea treated corn silage when dry matter of both silages was 30%. NPN treatment of silage signifi— cantly increased (P<:.025) DM intakes compared to untreated control corn silage. Anhydrous ammonia gas (.4 or .5%), ProSil (2 or 4%), and urea (.6%) were added to 33% DM corn silage (Huber gt E11: 1973c). The gaseous NH3 was sprayed onto the silage from a perforated steel tube as the silage passed through an auger box en route to the blower. The ProSil was mixed with silage at the blower and the urea was distributed evenly on top of the load of silage prior to delivery to the blower from a self unloading wagon. There were no differences in nitrogen recoveries due to form of NH3. Milk production (8 cows/sil- age for 77 days) was similar for all silages even though cows fed silages containing the two highest levels of NH3 received no soybean meal. Silage intakes were highest for the high 33 ammonia treatments. Anhydrous ammonia (.38%), applied directly to corn silage at the forage harvester; ProSil (2%), applied at the silo blower; and urea (.6%) applied to the top of the load were added to 33% DM corn silage and compared to untreated silage (Lichtenwalner gt gtt, 1972). Recovery of added ni- trogen at feeding time was 48, 88, and 91% for the respective silages. Intake of the control and the anhydrous ammonia silages was significantly lower than for the ProSil or urea treatments. Milk yields (8 cows/silage for 9 wk) were not different between treatments. Farm application of anhydrous ammonia to corn silage (Hillman £E.££;r 1973) at the forage harvester either directly as a gas or mixed with water in- creased silage crude protein 3.15 and 4.28 percentage units. This review of literature identifies a real need to further investigate and evaluate the very intriguing obser- vation that urea and ammonia treated corn silage have higher water-insoluble nitrogen levels than untreated silage. It has been theorized that this is due to: 1) enhanced microbial synthesis of protein during fermentation (Coppock and Stone, 1968); or 2) to a protein sparing action caused by reduced proteolysis (Coppock and Stone, 1968; and Bergen 23.21;! 1974) during fermentation. If in fact, either or both of the above phenomena are true there exists a tremendous potential to in- crease the level of NPN in corn silage based rations. Fur- ther work needs to be done to clearly elucidate this princi- ple. PART A. NITROGEN FRACTIONS, PH, DRY MATTER AND ORGANIC ACIDS OF N-P-N, MINERAL AND DISACCHARIDE TREATED CORN SILAGE 34 MAT ERI ALS AND METHODS Experiment 1. Pilot Silo Fermentation (1972-73) Freshly chopped corn silage (35% DM) in 56 kg por— tions was thoroughly mixed with additives and stored in pilot silos. Each silo was two, 004 gauge, 1 X 1.7 m transparent polyethylene bags (one inside the other) positioned inside a 210 1 metal drum. Table 2 describes silage treatments. Add- ed nitrogen was .23, .46, or .92% of silage fresh weight. Additions were: .5, 1, or 2% urea; l, 2, or 4% aqua-ammonia; or 1.8, 3.6, or 7.2% ProSil (NH -molasses-mineral suspension). 3 Control received no additive. Distribution of the silage additive(s) was achieved by spreading an even layer of the 56 kg of silage upon a large polyethylene sheet. The additive was then uniformly applied over the silage surface. The entire silage mass was stirred and blended with a shovel and then rolled and rotated several times in the polyethylene sheet to insure complete mixing. The treated material was then transferred to pilot silos, sampled (5009), evacuated of air with a vacuum cleaner and sealed by tying with a .3 mm cord. Containers were stored inside an enclosed barn on a concrete floor. Silos were again opened, sampled (5009) and re-evacuated of air on days 1, 3, 5, 10, 15, 20 and 40 and of fermentation. Temperatures were measured at the center of silage mass while the bags were open using mercury thermometers attached to wooden dowels. 35 Table 2. 36 Description of pilot silo treatment combinationsa Disaccharide or mineral additive 1% CaCO3 1% NaHCO3 1% Sucrose 1% Lactose .5% NaCl 1% CaC03+ 1% Sucrose 1% Lactose X X Nitrogen additive Urea(45%N) Aqua-NH3(22%N) ProSil(l3.6%N) .5% 1% 2% 1% 2% 4% 1.8% 3.6% 7.2% X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X aAdditives were thoroughly mixed into silage mass as a per- cent of silage fresh weight. silo. Each 'X' represents one pilot 37 Samples were immediately frozen at -20’ C to await chemical analysis. Frozen silages were comminuted with a commercial food cuttera to insure representative sampling. Dry matter (in duplicate) was determined on approximately 40 g fresh silage by drying in a forced-air oven at 80° C for 24 hours. Total nitrogen was determined on 5 g wet silage by macro-Kjeldahl procedures. Silage extracts were prepared by homogenizing 20 g wet silage and 180 ml distilled H20 in a Sorval Omni- mixerb for three minutes. The homogenizer cup was immersed in ice. The homogenate was strained through two layers of cheese-cloth and a 20 m1 aliquot of strained liquor was cen- trifuged 10 minutes at 15,000 rpm. The supernatant was used for determination of pHC and soluble nitrogen by micro- Kjeldahl. A second 20 ml aliquot was deproteinized with 50% sulfosalicylic acid (1 part SSA to 10 parts extract). The deproteinized extract was then centrifuged at 15,000 rpm for ten minutes and the resulting supernatant was analyzed for lactic acid and VFA. Colorimetric procedures of Barker and Summerson (1941) were used to determine lactic acid. The VFAs were analyzed by injecting 3 micro liters of the deproteinized sample into a Hewlett Packard F & M gas chromatographd using a glass Hobart Manufacturing Co., Troy, Ohio Ivan Sorvall Inc., Newton, Conn. Beckman Zeromatic SS3 Hewlett Packard F & M Scientific Co., Model 402 QIQU‘DJ 38 column packed with chromasorb 101 (80/100 mesh)e. The in- jection-port temperature was set at 225° C, the column at 225° C., and the flame detector at 240° C. Nitrogen was used as the carrier gas and flow rate was 30-40 ml per min- ute which created a retention time of approximately seven minutes per sample. Sample VFA concentrations were calcu- lated by comparing peak heights with those from a standard solution made with known weights of analystical grade acids in a stock solution diluted until concentrations comparable with samples were reached. Water insoluble nitrogen in silages was calculated by the difference between the total nitrogen determined by macro-Kjeldahl and the soluble nitrogen determined by micro- Kjeldahl. Experimental parameters from the various treatment combinations outlined in Table 2 were divided into three groups for statistical examination by analysis of variance and partition of single factor or treatment effects by ortho— gonal contrasts as outlined in Table 3. The mean square error terms from the first statisti- cal comparison (ten trts with 2 silos/trt) were used to test for single factor, main, and interaction effects for each experimental parameter of the remaining two comparisons be- cause the latter had only one observation per treatment com— bination. eJohns-Manville, Celite Div., Denver, Colorado 39 Table 3. Statistical organization of parameters from Experiment 1 Part A * l — 10 treatments, 2 silos/trt, 4 days sampled * 2 - 4 X 6 X 4 4 N-sources X 6 additives X 4 days sampled (one silo per combination) * 3 - 3 X 8 X 4 3 N-sources X 8 additives X 4 day sample (one silo per combination) l 2 3 Item 23 Item DE Item DF Treatments 9 Nitrogen 3 Nitrogen 2 Nitrogen (2) Additive 5 Additives 7 N-level (2) N X A 15 N X A 14 N X level (4) Error a from 1 Error a from 1 Control 2g. others (1) Error a = silo/ trt 10 Days 3 Days 3 a N X days 9 N X days 6 Days 3 A X days 15 A X days 21 Trt X days 27 N X A X days 45 N X A X days 42 Error b (silos X days)30 Error b from 1 Error b from 1 Total (n - l) 79 95 95 * Temperatures were obtained on 7 days (1, 3, 5, 10, 15, 20 & 40) while all other parameters were analyzed on days 0, 3, 15 & 40. 40 Experiment 2. Pilot Silo Fermentation (1973-74) Freshly chopped corn silage was ensiled in pilot silos as described in Experiment 1. Four harvests were made at estimated whole corn plant DM of 30, 35, 40 and 45%. Ex- perimental design at each of the above DM was a 4 X 3 factori- al replicated twice with the respective factors being: 1) an- hydrous ammonia application of 0, .24, .48, and .72%; and 2) water addition at 0, .8, and 1.6% of fresh silage weight. The anhydrous ammonia and water were added to silage via the mixing apparatus illustrated in Figure 3. Ammonia was metered into the mixing chamber using a regulator from a conventional anhydrous ammonia field applicator. Source of water was the farm tap water system. Silage was conveyed to blower at the rate of 500 kg/min, where the desired a- mounts of ammonia and water were added via the mixing appa- ratus. Thirty seconds were allowed for the ammonia-water mixture to equilibrate itself during which time the treated silage was discarded. After equilibration enough silage was diverted onto a large polyethylene sheet to fill two pilot silos and then the flow of silage was directed away to be discarded while the mixing procedure was shut down. Each pilot silo was filled with 56 kg of experimental silage. The air was evacuated, bags were sealed and silos transfer- red to an enclosed barn for storage. After 40 days, 1 kg samples were taken from the middle of each pilot silo and frozen (-20 C‘) for subsequent chemical analysis. Nitrogen, VFA, lactic acid, pH, and DM determinations were identical 41 Attach 3 m water hose to silage blower « 2. 1.9 cm pipe thread 3. 3.8 cm pipe about 40 cm long —-———-‘ 4. Water jacket 13? 5. Perforated 9.5 mm pipe 45 cm long with 32 holes 3.2 mm in diameter. 6. 1.9 cm hose pipe fitting for water hose 7. Pipe bushing, 915 mm to 3.8 cm 8. 915 mm pipe "T" 9. 9.5 mm to 3.2 mm busing 10. Ammonia gas from applica- tor meter manifold 3.2 mm pipe niples Figure 3. Anhydrous ammonia and water mixing apparatus (Standard black iron pipe and standard pipe fittings). 42 to those described in Experiment 1. Experimental parameters of this 4 X 4 X 3 factorially designed experiment were exam- ined statistically by analysis of variance and partition of single factor or treatment effects by orthogonal contrasts. RESULTS AND DISCUSSION Experiment 1. Temperature of NPN treated corn silage as affected by nitrogen source and level on seven fermentation dates is presented in Table 4. Temperature was not changed by nitrogen source or level. Temperature decreased (P<<.01) linearly from day one to day 15. Temperature for day 40 was lower (P-<.05) than that for day 20. The low temperature on day 15 coincides with the lowest daily mean outside tempera- ture and an extreme low the previous night of -8.9° C. Obvi- ously silage temperature closely paralleled ambient tempera— ture. There was no excessive heating in any of the silages. Temperatures were lower than those which normally occur in farm silos because of: l) the relatively small volume (56 kg) allowed heat from fermentation to be readily dissipated; 2) anaerobic conditions created by promptly evacuating the air reduced aerobic fermentation (Federson, 1971); and 3) the low ambient temperatures during October and November. Geasler (1970) reported mean temperatures of 25° C for the first 12 days of fermentation of corn silage harvested at ten maturities from 22 to 48% DM and stored in experimental silos, but he harvested earlier in the year and his experimental silos were placed in a warmer building. The pH values of the corn silages treated with three sources and levels of NPN and sampled on four different days are presented in Table 5. Control silage had a lower (P¢<.05) average pH than the nine NPN treatments; however, these 43 44 .moHflm Hmucweflummxm 03» EOum mommum>m ucwmwumwu coHumucwEumm mo mhmp now mwsHm> umasnmem «Hm. ADUHSOm w Hw>malzv ma.mafim.v oa.maae.v mH.MHAN.V wo.maaov cmmE Hw>wa :m00uuflz n.a m.m N.m| m.h m.m o.m m.vH cmwe magma moamuso gem. m.» m.m m.m N.NH >.¢H m.mH ¢.om came awn m.h >.m o.m «.ma «.ma m.ma N.om m. m.h m.m o.m H.NH m.va o.~m m.ma v. N.n m.m m.m o.mH m.mH N.om o.Hm N. v vm.ma HOmI mz m.n m.oa m.m ¢.NH o.qa ¢.>H v.om m. o.n o.m N.m m.HH m.va «.ma o.o~ v. m.> m.m m.m «.ma m.wa m.ma m.o~ m. w mm.mH mZIm3q¢ m.> m.m m.m «.ma o.ma o.ma m.o~ m. m.> h.m m.m o.NH m.¢a «.ma o.om a. m.n h.m m.m o.ma m.va o.ma m.om m. HH.mH mqu wo.ma m.n w.a m.h m.aa o.ma m.mH m.om o acuucou 2mm cme ow.,. om ma oa m m a pmpom w mumsom wouDOmlz mc0wumucmEuwm mo mama cwm0uuflz .mmmaflm auoo mo “Dov wusumummeu co newumucmEumm mo mmmm paw ammOHDMC mo Hm>wa cam mousOm mo powmmm .w magma 45 differences were least (P<:.25) on day 40 of fermentation. Urea treatment lowered (P<:.05) silage pH when compared to silage treated with aqua-NH4 and NH4-solution. The overall mean for pH within nitrogen sources increased as level of nitrogen addition increased with .4 and .8% added nitrogen being higher (P<<.01) than the control, and .8 being higher (P-<.01) than .2% added nitrogen. A significant (P<<.05) source X level interaction due to the inconsistent effect of urea compared to the ammonia treatments at the different lev- els of N addition and a rather large standard error for means makes subtle differences difficult to detect. Control and silages treated with .2% added nitrogen had similar pH values on day 40 that were significantly lower (P<1.05) than the two highest levels of the ammonia treatments and the intermediate level of aqua-NH4. There was a general decrease in pH with fermentation time. Day zero values were higher (P<:.01) than all others and day three values were higher (P<:.01 than those on day 40. A significant (P<<.05) day X treatment in- teraction was due to an inconsistent pattern noted for urea particularly on day three of fermentation. One would ques- tion the lower value for day three, but it coincided with a higher lactic acid (Table 6). The pH values (Table 5) are in general agreement with those reported by other researchers (Geasler, 1970; Lo- pez gt git, 1970a; and Cash, 1972) using similar experimental silos; however, such high levels of ammonia with the resul- tant high pH values have not been previously reported. 46 .moHflm Hmucmaflummxw 03D EOum mommuw>m ucmmwumwu coflumucmEuwm mo m>Mp you mosam> umasnmam mwm. mwm. 2mm Amou50m a Hw>walzv wm.m mm.m no.m mb.¢ CMOE GOHDOmIZ mm.h No.m mm.m mH.m no.m Nh.m mo.m vm.m mw.v mh.v hm.mam.v C005 ucwaummue ma.mAv.V He.mam.v wm.¢ hm.m $0.0 om.m Hm.b mv.m mm.v No.m ¢H.h mm.w mm.v hv.m mn.m mo.w wh.w mm.m mfi.m NH.> mm.v mm.v mh.m wm.v om.¢ mm.v mm.v mm.v mm.¢ mm.v mm.v mm.¢ hm.v H>.¢ mm.v ow ma m m sewumucwEuwm mo mama ma.axov cams Hw>ma ammOuuflz mm.> came >mo om.m m. mm.m a. mo.m N. v How: m2 vo.m m. oe.m a. mH.m m. a mzumsaa om.m m. Hm.m v. ma.m m. mm“: m¢.m o HOuucou o owppm w mousom cmeHDMZ. .wmmaflm suoo mo mm co cofiumucwEuwu mo mmmp pcm ammOHUwc mo Hm>ma cam wowsom mo nommmm .m manna 47 Lactic acid content of corn silages treated with three sources and three levels of NPN is shown in Table 6. The tremendous variation in lactic acid content of silages in this experiment as evidenced by the large standard error of the mean, makes statistical interpretation difficult. Urea appears to elicite more of a stimulatory effect on lac- tic acid production than the NH4-solution or aqua-NH4. How- ever, lactic acid content at .2% added nitrogen (the level recommended to farmers) on day 40 was substantially higher (6.11 and 5.52 yg. 4.81) for the ammonia treated silages. The important biological phenomenon starting at .4 and mani- festing itself at the .8% added nitrogen was the marked inhi- bition of lactic acid production with the ammonia treatments. There are two explanations for this reduction of lactic acid: First, initial application of similar levels of ammonia has been shown to destroy fungi present in fresh-cut corn silage (Britt, 1973) and eliminate or significantly reduce all mi— croorganisms in high moisture shelled corn (Bothast gt 21;! 1973, 1975) and; Second, most rod shaped forms of lactic acid bacteria cannot grow in media with an initial pH greater than 6.0 (Stanier gt 21;! 1970). The pH values (Table 5 observed for ammonia added at .4 and .8% N were initially above those for optimum growth of lactic acid bacteria (Lang— ston gt gtt, 1958). The low level (.2%) of nitrogen result- ed in the highest (P<:.05) concentrations of silage lactic acid. Lactic acid at day zero was lower (P<:.01) than at days three, 15 and 40. 48 .moaflm Hmucmfifluwmxw 03» 50um mommuw>m “commummu pcm mammn who D co pwmmwumxw mum coflumucmEumm no name How mmsam> umannmfim Emma Hm>ma cmeuuwz cmmE wan m. ¢O N. Homnamz w. v. N. v mzumsva m. ¢O NO mono o acuucoo poppm w wou50m om.H ADOGDOm w Hw>malzv mo.NAm.v mm.HAv.v ma.wAN.v mo.mfiav mm.a H>.m wh.m mh.N OH. ma. ea. No. so. No. mm.H mm.m Nm.a oo. mo. hh.¢ Nm.m Nv.m Ho.v NH. HH.N mm. 00. NH.N oo. mo. om.H No.m mo.N oo. NH. Ho.m Ha.m No.m mm. wo. No.a mm.m hh.v mm.m mw.m ma. mo.m NN.m bh.m wm.m «o. mh.v Hm.¢ mo.m ON.m mo. Nm.m mo.m mo.m mm.m wv.m Nm.v Nm. 2mm game came ow ma m o mousomlz ucwEummuB cofiumucwEumw mo mmmo m cmm0uuwz .mmmawm auoo mo pfiom ofiuoma so cofiumucmEuwm mo mmmo paw cmm0uuwc mo Hm>wa cam wousom mo uowmmm .w manna 49 Lactic acid values (Table 6) for control and urea treated silages are similar to those reported by Lopez gt .21; (1970a), Thomas gt gt; (1975), Cash (1972), and Geasler (1970) at equivalent maturities. Acetic acid values for control silage were consis- tently lower (P4:.05) than those for the NPN treated silages (Table 7). Values for urea treatment were generally lower than for the NPN treated silages (Table 7). Acetic acid values for urea treatment were lower than for the NH -solu- 4 tion and aqua-NH4 treated silages at the two highest levels (.4 and .8%) of nitrogen addition on day 40 (P<:.05). In fact this elevation of acetic acid concentration coincides with the depression of lactic acid as is graphically portray- ed in Figure 4. Acetic acid concentration increased linearly as fermentation progressed with day 15 values higher (P<:.01) than day zero and day 40 values higher (P<<.01) than all oth- ers. Level of added nitrogen and acetic acid concentration of silage were positively correlated, i.e. the .4 and .8% levels of added nitrogen stimulated the highest (P<<.05) lev- els of acetic acid in silage. Total organic acid content of corn silage (Table 8) paralleled that of lactic acid. There was a tendency toward higher (P<<.10) total organic acids with urea compared to aqua-NH and NH4-solution. The .2% level of nitrogen addi- 4 tion tended toward higher total organic acids than at .4 and .8%. This was particularly true for the NH4—solution and aqua-NH4 treatments since lactic was so markedly reduced 50 .monm Hmucwefiummxm 03¢ EOum mommum>m ucwmwumwu paw mammn mun D co pmmmwumxw mum coflumucmEuwm mo mwmp you mosam> awasnmam «AN. mom. ZMm AmouSOm w Hm>maazv Nw.a mm.H NN.H oo.H Gme MUHDOmIZ mm.aam.v mm.H on.H mm.H mw.H mh.a bN.H mN.H mH.H NN.H oo.H mefi ucmfiummua mm.aav.v mN.HAN.V mm.N mm.a mm. mH.m Nb.H ON.H Nm.N NH.N no.H Nm.N mm.H «h. mm.N hv.a Nm.a mm.N mv.N mm. ON.N Nm.H Nm. mm.a mH.N om. ho.N NH.H vo.H mo.N om.H mo.H wb.H ov.H ow. O¢ ma m oo.aaov acme Hw>wa somOMDNZ mm. cme mmo 0N.H m. mm. a. mm. N. v Howl m2 NN.H w. oo.H a. Nm. N. w mzumsa< ow. m. ow. v. Na. N. mm“: ow. o acuucou o cocoa m wousom 6 coHpmucmEuwm mo wmma cmeuufiz .mmmawm auoo mo pflom vaumom co coflumucwEumm mo mmmp cam comOuuflc mo Hm>ma paw mousom mo uommmm .a magma 51 (a) O O Acetic acid N 0 (percent of DM) N U! A H U1 —————— ’ a” ” ’4‘ .4. — _ __ __ __. .. __ 4’ nnnnnnn r) I . ”’ /./ I ..’ I” I’././ g #A ’I/ \1 Lactic acid (percent of DM) Figure 4. .2 .4 .8 Percent added nitrogen Effect of source and level of nitrogen upon lactic and acetic acids after 40 days of fermentation. 52 .moHfim HmucwEwuwmxw 03» EOum womanm>m ucmmwummu paw mambo hop D co cwwmmumxm cofiumucmaumm mo m>m© now mmsam> unasnmem mm.H Hm.a 2mm ADOHDOm a Hw>malzv mm.m mN.m mo.m 5H.v .CNOEA OUHSOWIZ ¢H.maw.v mo.N mN.m mm.o mm.N mo.m mm.v mm.q mN.v No.m 5H.v Emma #CGEUMQHB vm.ma¢.v mm.mANv oa.m Hm.m mo.v Nm.m @M.N om.a mm.m mN.v mm.H oa.m mm.oH mm.m mm.N mm.m mm.H Nm.m or.v mm. Nm.m om.m mo.N wv.m ¢N.m om.m mN.b mm.v mm.v mm.m hm.m mN.OH Hh.m wm.v mo.m 0%. ma m na.waov came Hw>wa cmm0uufiz mm. cme mam H¢.H m. mu. w. an. N. v Howl mz Hm.H m. mH.H v. mm. N. a mzumswa mm. m. em. a. ma. N. mmuD am. 0 HOuucou o omppm.w mousom m CONDMDCmEuwm mo mwmo cmm0uuflz .mpfiom uficmmuo Hope» co c0wumucwEumm mo mmmp new cmeuuflc mo Hm>ma 0cm mousom mo uowmmm .m mHQMB 53 (Table 6 and Figure 4). Total organic acids were higher (P<<.05) on day 40 than day zero. Other differences were not detected because of the large standard errors for means which is indicative of the unusually large amount of varia- tion in treatment combination response. Dry matter content of all silages decreased slightly as fermentation progressed (Table 9). Values on day 40 tend- ed to be lower (P<:.25) than those on days zero and three. Similar results were reported by Lopez gt_gtt (1970b). This phenomenon was possibly due to a loss of volatile organic acids during oven drying coupled with the evolution of CO2 and the production of H20 in the silos during fermentation. Total nitrogen of corn silage (Table 10) was increas- ed (P<:.01) by each incremental addition of nitrogen at en- siling. Increases due to urea were greater (P<<.05) than for aqua-NH4 and NH4-solution. Nitrogen addition was calculated to be equal from each source. An explanation for these dif- ferences is that less nitrogen from urea was volatilized dur- ing application and mixing than from the aqua-NH4 and the NH4- solution. The NH4-solution lost less NH3 during application and mixing than the aqua-NH4 probably because of a lower NH4+ concentration or a possible binding by minerals and molasses. TN at the .8% N level on day 40 was actually lower for the urea silage. This could have been due to sampling error or a reflection of more stability of ammonia compared to urea ' treated silages (Britt, 1973). These barrels had been opened seven times for sampling by day 40 and secondary fermentation 54 .moHflm Hmucwefluwmxm o3u EOum mmmme>m ucmmwumwu coflumucwEuwm mo mmmn now mosam> umHstBm ham. mNm. 2mm mousom a Hw>walzv h.vm m.¢m C605 wou50m|z o.mmxm.v b.vm w.vm o.mm m.vm N.mm m.wm ¢.mm b.vm m.mm m.vm C605 ucmEummuB a.amae.v m.emAN.v m.mm n.vm v.mm o.mm m.mm m.¢m ¢.mm h.mm o.mm ¢.¢m w.mm m.vm m.vm h.vm m.¢m H.¢m m.mm N.hm m.mm H.mm h.¢m m.vm v.mm 0.0m m.mm N.vm N.mm ¢.Nm m.vm m.vm m.mm m.vm w.mm 0% ma m .m cofiumucmEumm mo mama m.wonv cme Hw>oH cmmOuufiz m.mm came man H.mm m. N.¢m e. o.>m N. w HOmI mz o.mm m. N.mm v. o.mm N. a mzumsaa m.mm m. b.vm v. m.mm N. mmuD v.mm o Heuucoo o cocoa w wousom cmeHDMZ IcmEuwu mo mmmp can cmmOHDNc mo Hw>wH cam mousom mo uommmm .mmmaflm Cuoo mo ucwucou umuume man :0 coflumu .m magma 55 .moaflm Hmucmefiummxw 03» EOuu mommum>m ucmmwummu mam mambo hub D co pmmmwumxm mum cofiumucmEumm mo mama now mmsam> amazemem NmN. ADUHDOm w Hm>malzv mNN.mAm.V omm.N.e.v bmo.NAN.V mmm.aaov Nma. Nam.N mhv.N ham.N mmm.N meN.m wam.m mmm.m owo.m omo.m mm¢.N Hmm.N oaw.N mam.N www.N aom.a Nmm.H «mm.a ohm.a mmm.a mom.N meo.m ovm.m mom.N mNb.N nON.m mmm.N mmm.N vam.N NON.N wmm.N mom.a mwo.N «hm.H Hoo.N onm.a hw¢.N wwm.m hma.m HN¢.m mvm.m mmm.m mvb.N onw.N NHh.N 5mm.N omn.N oom.N Nom.N NmN.N emH.N mmN.N cam.N mmm.H mmm.a eam.H mNm.H v>¢.H oem.a 2mm cme . :mmE. . ow ma . m 7 o wOuDOmlz ucwEummuB coflumucwEuwm mo.mmma fl came Hm>ma cm00uuflz cmmE mma w. v. N. Hemuamz m. fi. N. a mzumsa< m. a. N. ammo o acuucoo wmppm,w mousom .cwmouuflz .wmmaflm cuoo mo ammOuuwc Honey :0 coflumucwEuwm mo mama 0cm ammouufic mo Ho>wa Dam ocusom mo Dowmmm .oa manna 56 could have caused a loss of nitrogen. The total nitrogen content at .8% added nitrogen was higher (P¢:.01) than .2 and .4 and .4 higher (P«<.01) than .2. The only other dif- ference was that for day three total nitrogen values tended to be lower than for days zero, 15 and 40. Lopez gt 21;. (1970b) reported slightly lower total nitrogen at urea addi- tions equivalent to the .2 and .4% added N of this study, but ground shelled corn was also added at either 3.5 of 7.0% of silage fresh weight which would dilute the total nitrogen concentration. Total soluble nitrogen (TSN) of control silage was lower (P<:.01) than the other nine treatments (Table 11). TSN values for all levels of urea were higher (P<:.05) than those for aqua-NH4 and NH4-solution because of greater ini- tial incorporation of total nitrogen (Table 10). Likewise, when all N sources were averaged, .4 and .8% added N result- ed in higher (P<:.01) levels of TSN than .2, with .8 being higher (P<:.01) than .4%. TSN values on day zero of fermen- tation were not different (P<=.25) from the other days. Day 15 values tended to be lower than days zero, three and 40 but there was a significant (P<fi.05) day X treatment inter- action and the difference between duplicate silos was also significant (P<:.05), i.e., the observed difference was not statistically significant. Control silage TSN was unchanged as fermentation pro— ceeded from day zero to 40. This is not in agreement with the bulk of published research. Johnson gt a1. (1967), Lopez 57 .moHNm Hmucmeflummxw 03D EOum mwmmum>m ucwmwummu pcm mammn hue m :0 pwmmwumxw mum coflumucmEumm mo mmmp now mmsHm> amasnmem mON. mou50m w Hw>walzv mao.NAm.oV Nmm.aaw.ov nmm.AN.ov mov.flov cmmE Hw>wa comOHDMZ moa. omm.a mMN.H an.H va.H cmme man omo.N 65¢.N mmo.N NNH.N ONm.H m. mom.H mmv.a NmH.H hmm.a onm.a w. com. eam. mmh. mmm. New. N. w Nav.a Howl mz rah.a omm.a mmm.a mam.a th.H m. hHN.H NmH.H mma.a vom.H NmN.H w. can. mow. vmm. Nmm.. mam. N. v mmN.H mz mswm NmH.N oom.H ona.N mh¢.N NNH.N m. Nmm.a vbm.H mmq.a mmm.a mom.a e. Nho.a woo.H mNm. Noa.H omN.H N. mom.a mouD mow. mow. «me. mam. omm. mmw. o HOuucou 2mm cme came ow ma m. o poppm.w mousom mousomuz ucmaummue mcoflumucmEumm mo mmma ammouuwz .wmmafim Cuoo mo cmm0uuflc mansaom Hmuou co coflumu IcwEuwm mo mamp 0cm cmeuufic mo Hw>wa paw wOHDOm mo uowmmm .HH wanna 58 gt_gtt (1970b), Geasler (1970) and Cash (1972) have all ob- served substantial increases in TSN during fermentation as a result of proteolysis. Bergen gt El; (1974) showed that the TSN content of control corn silage accounts for about 35% of the total nitrogen after 12 hours of fermentation and remains rather constant thereafter. At 0 hours fermentation it ac- counted for only 13% of the TN. It is possible that some proteolysis occurred in all silages on day zero before the samples were frozen and thus the initial TSN value remained constant. Cool temperatures coupled with anaerobic condi- tions in the experimental silos may have further minimized protein degradation. The effect of source and level of nitrogen on water insoluble nitrogen (WIN) was negligible (Table 12). The only observed differences were that day three values appeared low- er than the values for 0, 15 and 40 days; however, the dif— ferences between duplicate silos was significant (P<=.05) making statistical interpretation of results extremely diffi- cult. The control silage WIN values were not decreased by proteolysis during fermentation as is usually the case (Lopez 'gt 91;! 1970b; Johnson EE.§£;I 1967; Cash, 1972; and Geasler, 1970). There is normally an increase in water insoluble nit- rogen with ammonia additions (Huber and Santana, 1972; Huber, 1973c; Beattie, 1970; and Cash, 1972). Explanations for this abnormality are: 1) the corn silages may have already under- gone proteolysis before being treated with NPN, or 2) the 59 ucwmwumwu cam mammn hub m :0 pwmmmumxw mum .monm Hmucmefiummxm ozu EOum mommum>m c0wumucmEuwm mo mhmp How mwsam> umasnmam 0mm. ADUHDOm w Hw>walzv amm.axm.v mma.ala.v oom.HAN.v oma.axov came Hm>ma cmeuufiz Nwa. HmN.H wwN.H mod. mom.H cmme mmo mna.a mwo.H NmN.H mmm. omv.H m. mHH.H mHH.H th.H own. me.H v. mmH.H mmH.H wha.a Hmo.a qu.H N. w mmH.H Howl mz NNm.H omm.a vNN.H ¢OH.H omm.H m. pmN.H mo¢.H omH.H mom. mom.a q. NON.H mbN.H HmN.H OHH.H va.H N. v mmN.H mzumst NON.H SON.H NmN.H «hm. v>¢.H m. NmH.H mmN.H th.H omo.H mNH.H v. mNN.H mmv.a eNm.H Noo.H mmo.H N. woN.H mono oma.a omH.H omH.H mna.a who.H Noa.a o H0uucoo SMm some CmmE ow ma m o pmppm w wousom ocusomlz ucmEumwuB mcoflumucwEuwm mo mama cmeuqu .cmmOuuflc wasHOmCN umumz co coflumucwsumm mo mmmp paw comOuufic mo Hw>ma Dam DUuDOm mo uowmmm .NH magma 60 cool temperatures in the barrels and the evacuation of air (creating rapid anaerobic conditions) may have inhibited proteolysis. The mean values for control and nitrogen source, di— saccharide or mineral additive, and day of fermentation on temperature of corn silage are shown in Table 13. Tempera- tures for individual treatment combinations are presented in Appendix Table 1. Standard errors of means were calculated from the mean square error terms outlined in Table 3. They are larger than those reported in Tables 4 through 12 because of only one observation per treatment combination, i.e. SEM = the square root of MSE instead of the square root of MSE/Z. Data were analyzed statistically as two separate factorials but are presented together in the same table for brevity and clarity. Nitrogen source had no significant affect on tem- perature. In the 3 X 8 X 7 factorial mean temperature of control and CaCO3 silages, averaged across days and N-sources tended to be lower than those for sucrose alone and the two CaCO3 and disaccharide combinations; however, the standard error of the mean was too large to allow one to say that these differences were statistically significant. The day effect on silage temperature was similar to that reported for level and source of nitrogen in Table 4, i.e. temperature decreased (P<<.05) linearly from days 1 and 3 to day 15 where they plateaued near 8°C for the remainder of the experiment. Silage pH values in the 4 X 6 X 4 factorial (Table 14) were generally lower for control than the N-sources and lower 61 .wm. um Humz umwoxw .wmmHHm nmwum mo NH um pwppm HmumcHE no prumnoomme comm .meHHm smwum mo NN. um poppm cmeMDHzm eve. Hm>Hqupm w onuDOmrzv mmm. lxmov am.MH wm0uomq mm.m._n meM 3m a>.n ow oomo mm.m om oa.mH Homz mm.m mH mm.mH mmouomq mo.NH OH Hm.mH mm Loom a nm.mH m om.mH m oomo na.mH «How: mz mm.mH m hm.MH oommz mm.MH mzsmswa mm.om H mH.mH HOHDcoo ow.MH mm”: HmHuouomm A x m x m «5.5 oa Hm.m om mm.mH Homz mm.m mH am.mH wmouomq a mm.HH OH Hm.mH mm Loam oa.mH aHow: az om.mH m Hm.MH m oomo nN.MH mzumsa< Hm.mH m vm.mH oommz mm.mH mono mm.o~ H mH.mH Heuucoo Nm.mH Heuucoo HmHuouomm a x m x a 2mm cam: Nam cmmz aw>HuHop« cmmz mwOLDOmIz .coHumucwEumm mcHusp muommuw chE Huey wusumummEmu wmmHHm Cuou .mH mHnt 62 memm uch so pwscHucoo mHntV mm.m em.m mm.a Hm.a m>m mousOmuz mm.¢ mH.v mm.v om.v mN.v ov mv.¢ mv.¢ Hh.v mv.v mN.v mH «m.¢ N>.m Nm.m m>.m Nm.m m mH.m Hm.m oo.m mH.m om.m om.m o wm0uosm Hm.m ma.m aa.o mm.m m>m mousomnz Hm.¢ No.m Nm.v m¢.m mm.v ow mm.m wm.m m¢.m m¢.m hm.v mH mm.m om.m mm.m vm.m HH.m m m mN.o mm.m mo.m NN.m mm.m om.m o oummz mo.m NH.m om.m mm.m m>m wouDOmIz oo.m oo.m mm.v oo.m mo.m ow Nv.m mm.m mm.m mm.m wm.m mH Nh.m No.m Hm.m mm.m NH.m m m Hm.m No.5 hm.> mo.m mm.o mm.m o oumu No.m Nb.m mm.v o>.v m>m mDHDOmIz Nm.v mm.v Nm.v mm.v 5N.v ow om.¢ mm.¢ mm.¢ mm.¢ Hb.¢ mH mo.m h¢.m mh.m mm.v mm.v m «N.m em.m No.m mH.m NH.o ow.m o Heuucoo 2mm muommmw chE .mmm Homl mm HuH©©¢ m>Hanp¢ man w0u50mlz mo mac .mmMHHm cuoo mo mm :0 coHumucwEuwm mo map can .m>HuHU©m .wousow cmmOuuHc mo uummmm .vH mHnme 63 .mw>Hqu©m HauwcHE no prumnoomme nmsuo HHm uOm mcoHum>uwmno mHmch 0cm Amcocv H0uucoo mom onHm mumoHHmsp EOum momma mum mwsHm> coHumcHneoo ucmEumwuB .wmm mH um mw>Hqupm uwnuo cam wN. um Dmppm coHusHOmlw m2 0cm Ham ammum mo .wm. um Homz Damoxmvn mzumsvm .mmu: EOum comOMDHzm omm. mm.¢Hoqv mw.vaHv mo.mamv Hm.haov muowmmm chE mma cow. Am>HuHccm av H>.m hm.m mN.m Nm.e muowmmw che wouDOmlz AH.m mm.m Hm.a an.a m>m mousomnz mm.¢ mm.¢y NN.¢ mN.¢ mm.¢ o¢ wm.¢ om.v mm.¢ m¢.¢ mm.¢ mH mw.¢ hm.m mm.m om.¢ hv.¢ m 0H.m OH.h Nm.b ov.m mm.m mm.m o HUMZ mm.m fim.m mb.¢ m¢.w mbm mOuDOmIZ om.v oN.¢ hfi.¢ MH.¢ oo.¢ ow v¢.¢ Nm.¢ mm.¢ wm.v NN.¢ mH Nh.¢ mm.v mm.m wm.v mm.m m mo.m dm.m mm.h mN.w hm.m mm.m o meHOMH 2mm .muowmmw CH 54.. >m Homlvmm meIDDwd mmuD Heuucoo coHumucwEuwm m>Hqun¢ wemqup< wUHDOmIz mo ace 3 pmscHucou .vH mema 64 for urea than aqua-NH and NH4—solution; however, these ap- 4 parent differences disappeared by day 40. Within dissacha- 3 and NaHCO3 tended to in- crease overall pH more than the other additives. This appa- ride or mineral additives, CaCO rent difference was still evident on day 40. There was a consistent drop (P<1.05) in pH as fermentation progressed with values on days 3, 15 and 40 being lower than those on day zero. The 3 X 8 X 4 factorial design includes all of the treatment combinations of Table 14 except the six control si- lages to which no nitrogen was added. The additional two ad- ditives (CaCO3 + sucrose and CaCO + lactose) and their treat— 3 ment combinations with the three NPN treatments are presented in Appendix Table 2. The general effect on pH was the same as discussed for Table 14, i.e. NaHCO3 and CaCO3 alone and in combination with sucrose and lactose tended to elicite slight- ly higher average and final pH values than the remaining min- eral or disaccharide additives. The intitial increase in pH with ammonia treatments was similar to that previously observed in Table 5 at the .2% level of N addition, but by day 40 any differences due to NPN treatment had disappeared. The mean effect of the mineral and disaccharide additions was to increase final pH by 0.2 units compared to the control and NPN treated silages. Lac- tose alone (lowest pH value, 4.0) and in combination with NPN additives caused the lowest pH values. It is theorized that lactose was a preferred substrate for lactic acid bacteria in 65 the silage and hence the low pH value. The ammonia pgt gg increases silage pH and the NH4+ ion combines with acetate and lactate to thus neutralize these acids and extend fermen- and NaHCO tation. CaCO contribute their respective anions 3 3 to the silage media and raise the pH. Limestone (consisting mainly of CaC03) has long been shown to increase silage pH (Owen, 1971; Johnson gt gtt, 1967). Silage lactic acid values even on day 40 were quite erratic (Table 15). Generally higher mean values were noted for those treatment combinations containing the NH4-solution. The final lactic acid concentration on day 40 was higher for NH -solution (6.34) than for aqua-HN4 (4.74),-urea (3.80) and 4 control (3.41) silages. Sucrose and NaHCO additions to si- 3 lages tended to lower (P<<.25) lactic acid especially on day 40. There was a significant increase (P<<.05) in lactic acid of all silages from day zero to 15. The same general trends for silage lactic acid as seen in Table 15 were manifest in the 3 X 8 X 4 comparison (Appendix Table 2). Lactic acid concentration was lowest on day 40 for the sucrose and lactose treatments and highest for CaCO3 alone and for CaCO3 in combination with sucrose and lactose. CaCO3 has been shown by other workers (Owen, 1971; Johnson gt gtt, 1967) to stimulate silage lactic acid. NaHCO3 and sucrose both lowered lactic acid compared to CaC03, but the depression was much less than for the high ammonia addi— tions (Table 6). The general trend for increased lactic acid with time 66 memm uch co pwscHucoo anmev mm.m mo.N OH.N mo.N m>m wouDOmIz wm.m mo.o mm.H NH.N mN.m oe vN.¢ mN.m ON.m wm.m Hm.H mH NH.N NN.N bw.H mm.H no.m m mv.N oo. oo. oo. oo. oo. o wwOuosm mv.N Hm.m mm.N mH.m m>m mDMDOmIz om.m hh.H NN.m em.N mo.m ow nm.v om.v mm.v mm.¢ mv.w mH NN.N NN.m m¢.m mH.N mm.N m m em.N oo. oo. oo. oo. oo. o oommz V mo.m am.m ma.m om.m m>m mousomtz m¢.m Hm.OH mo.m mo.v em. ow vm.v Nm.m Hm.¢ bh.v mm.m mH mm.N NH.N mo.H NN.N ON.v m m mN.m we. mH. oo. oo. oo. o oumu an.a oo.m ma.a mo.m m>m mousomuz mo.m Nm.m HH.m Hm.v mm.m ov mh.m Nv.m No.m mo.m mv.m mH hm.v Ho.¢ mm. 0N.m Nm.¢ m Hm.m «H. NH. we. mo. em. 0 HOHDCOO mmm wuommmw chE .m>m Homlvmm vm21m3m¢ mmub HOuucoo . coHumucmEumm m>Hqu©< m>Hquc¢ man wouSOmIz mo awn m.mmMHHm cuoo mo ucmucoo pHom oHuomH co coHumu IcmEumm mo map can .o>HuH©©m .mou50m cmeuuHc mo nommmm .mH mHDma 67 .HmumcHE uo mpHumnoomme uwnuo HHm you mcoHum>ummoo mech Dam HOuu Icoo now moHHm mumoHHmsp EOum mamme mum H29 mo unwoummv mwSHm> coHumcHnEoo ucwEummuB .mmm NH um mw>Hqupm uwcuo Dam wN. um poppm coHusHOmI e Ham ammum m o xwm. um Homz Damoxmvn mz can emznmswm .mwus EOum cmeuqum mm.H nm.vaovv Hm.¢AmHV NH.NAMV 0H.on muommmm chE hmo em.N Hw>Hqu©m av NN.N om.N wm.m mm.N muomwmw chE mumsOmlz ma.m ma.m mm.m m~.~ m>m mousOmnz Nm.v mv.b mo.m hm.¢ vv.H ow eh.¢ HH.m om.m No.m MN.¢ mH NH.m Hm.H mo.H OH.m NN.H m NN.N ow. oo. oo. oo. om.H o Homz mm.m nm.m mH.a mH.m m>m mousOmsz NN.N mem mm.v wN.m mm.m ow mm.m ww.m mm.m ev.m Hw.¢ mH mm.m NH.N om.H NN.N NN.N m vq.m oo. oo. oo. oo. oo. o mucuomq 2mm. muowmmw CHmEV dmflm Homlwmz. «SZIDDwm. mwubfimmmmmmm coHumucmEuwm w>HuH©p¢ m>HuHUp« >60 ocuSOmlz. mo awn n .pmscHucoo .mH anma 68 (Table 6 and 15) and concurrent decreases in pH (Table 5 and 14) is logical; however, pH on day 40 of the silage treated with NH4-solution was not different from control, urea or Aqua-NH4 but lactic acid was increased. This indicates that- ammonia does extend fermentation by neutralizing organic acid (Huber and Santana, 1972; Huber, 1973a and c). Acetic acid levels (Table 16) tended to be lower for control than for N-treated silages. Values on day 40 were lower (P<:.05) for control compared to the NH4-solution treat— ed silage. CaCO3 and NaHCO3 additions generally resulted in elevated acetic acid compared to sucrose and lactose and these differences were significant (P<:.05) on day 40. Trends in acetic acid were similar for the 3 X 8 X 4 factor- ial (Appendix Table 3 and Table 16). There was a tendency for higher acetic acid levels on day 40 for NH4-solution than and CaCO for urea and aqua-NH4. NaHCO elicited higher 3 3 (P<:.05) levels of acetic acid on day 40 than sucrose and lactose alone or sucrose in combination with CaC03. The in— crease in acetic acid was consistent from day zero to 40 with day 40 values higher than (P<<.05) days 0, 3 and 15. In con- trast, lactic acid reached a plateau after 15 days. Acetic acid levels seemed to parallel those of lact- ic acid (Table 15) and were increased most (.4 percentage unit) by NH4-solution treatment. However, the extremely low lactic values for the treatment combinations CaCO3 + control and NaHCO3 + NH4-solution on day 40 correspond to unsually high acetic acid values. This same inverse relationship was 69 Amman uxmc co poscHucoo mHQmBV mo.H mm. on. we. m>m mousomuz mm.H mm.H oo.H_ mm. em.H ow em. mm. HH.H am. we. mH mm. mm. mm. mm. Nm. m Nm. me. am. mm. om. mm. o mmOuosm aa.H om.H mm.m om.H m>m mousOmuz wm.m om.w «e.N em.m om.N ow mm.H hm.H mm.H NN.N ms. mH mm.H hm. o¢.H no.H Hm.H m m ob.H om. Nm. Nm. me. me. o oommz am.H ma.H ~>.H mm.H m>m mousOmuz wv-m Hm.m. mH.m no.m_ NH.N ow on.H mm.H mm.H NN.N mm.H mH no.H eo.H mm. HN.H mo.H m m nw.H me. me. om. «m. mm. o oumu mm.H GN.H -.H co.H m>m wousomuz NH.N Nm.N ON.N. mo.N on.H ow w¢.H mm.H Nm.H om.H ov.H mH mp. an. Nm. wo.H we. m HN.H we. mm. Nm. Na. 0%. o H0uucou 2mm muowmmw chE .dmmm. HomlHuH©©¢ m>HuH©o¢ mam wouDOmIz mo wmo .mwmmHHm choc mo ucwucoo pHom oHuwom co coHumucmE Iumw mo map Dam tw>HuH©©m .mousow cmeuuHc mo Dommmm .mH mHDmB 70 NH um mw>HuH©©m umauo cam wN. .mw>HuH©©m prumnoomme no HauwcHE umnuo HHm now mcoHum>uwmno mHmch 0cm HOuu Icoo mom moHHm mumoHHmsp EOum mcmwe mum Asa mo uco0ummv mwSHm> coHumcHnEOU ucmEummuB .wmm Ham 3 mmuu mo .wm. um Homz admoxmvn um pwpom coHusHomlvmz pcm aEZImsqm .mwu: EOum ammOHDHzm Hmw. N¢.Nonv mm.HHmHV wm.amv mv.Hov muowmmm _ chE wmo mom. Aw>HuH©©m wv mv.H mN.H Nm.H mo.H muommmw chE wousomlz ma.H mm.H ao.H an. m>m mousomuz mm.N NN.N mm.m mm.N N04H ON NN.H mm.H om. mm. hm.H mH om. we. mm. Nb. hv. m hH.H md. mm. Nb. Hm. mm. o HUmZ mN.H ¢o.H mm. Hm. m>m mUHDOmIZ Hw.H mm.N mm.H HN.H om.H ow vH.H bH.H H©.H NN.H mm. mH mm. om. mm. m¢. mm. m Ho.H mm. mm. hm. mm. «N. o mmouomq flmw muUmmmm.CHmE .m>m Howl mm «azumswfl mono HOuucOO coHumucwEuwm w>Hqupd w>HuH©©¢ man mUMDOmIz. mo awn n .pmscHucoo .mH mHQMB 71 noted when lactic was depressed by high levels of ammonia (Figure 4). Nevertheless, lactic acid values were normal on day 15, suggesting that secondary fermentation may have oc- curred due to air leakage into the plastic bags and may have resulted in conversion of lactic to acetic acid. Britt (1973) observed a threefold reduction in lactic acid content of corn silage seven days after bi-daily aeration; however, acetic acid values were not reported. Total organic acids (TOA) tended to increase more (P«<.25) in silages treated with NH4-solution than control, urea or aqua-NH4 (Table 17). Day 40 control silage levels of TOA were lower (P<<.05) than all others, with urea and aqua-NH4 lower (P<:.05) than the NH4-solution treated silage. There was a tendency for sucrose treated silages to be lower (P<<.25) in TOA than all other disaccharide or mineral addi- tives. Day 40 TOA levels were highest for CaCO3 treated si- lages and lower (P<:.10) for sucrose than all other disaccha- ride or mineral additives. Total organic acids increased with fermentation time but differences were slight between day 15 and day 40. The trends in TOA levels described for Table 17 were similar to those noted for the 3 X 8 X 4 factorial analysis (Appendix Table 3). Day 40 TOA levels for silages treated with CaCO alone or in combination with sucrose and lactose 3 were not different; however, sucrose and lactose silages re- sulted in lower (P<<.10) TOA than when added in combination with CaC03. 72 .wmmm uxmc co pwscHucoo meva mm.v NN.N mm.N ob.N m>m wouDOmnz mo.m om.N mH.w mb.w ow mo.m NN.N Hm.m NN.N NN.N mH NN.N NN.N NH.N m¢.N mm.m m om.m Hm. am. mo. mm. me. o mmOuosm ma.a om.a mo.a Gm.a m>m «casemuz hN.h hm.m. om.b mw.m No.m ow o¢.m hm.m m¢.m mm.h wN.m mH mm.¢ mm.w mm.w Nw.m m¢.v m m am.w Nm. Nm. Nm. me. mm. o oummz Na.o Hm.a am.a GH.a m>m mousOmnz oo.m mv.qH mm.¢e NH.N Ho.m ov mm.m mm.h «H.m mo.b nw.m mH No.6 om.w m¢.N mm.m m¢.m m m Ho.m me. me. om. em. mm. o oomu om.m mm.a No.8 AH.4 m>m mousOmuz mN.> OH.m NN.N mm.m Hh.m ow NN.N mm.oH oo.m hm.o em.v mH mo.m Nm.m mo.N wN.0H mo.m m Hm.m me. an. om. me. am. 0 H0uucou mmm muowmmm chE .m>m. Howl mm Hqup< m>muH©©¢ mma wousomlz mo mac n .mmmMHHm auoo mo ucmucoo pHom oHcmmuo Hmuou co coHpmu Icmauwm mo amp paw .w>Hqupm .mOHDOm cmmOHDHc mo powmmm .NH anma 73 NH D6 mw>Hqup6 umsuo 6:6 wN. D6 @6666 COHDSHOme .mw>Hqup6 H6umcHE no 66Hu6noo6me umzuo HH6 uOm mcoHu6>ummno mHmch 6:6 Heuu Icoo uom moHHm mu6oHHmsp EOum 6:665 6u6 Asa mo ucwouwmv mwsH6> coHu6cHQEoo ucoEpmmuB m6HHm cmwu mz 666 v 6 60 “am. 66 H662 ummoxmvn $216566 .66“: EOum cwm0uqu6 om.N No.>Aowv Nm.oAmHV mN.vAmv mm.Hov muommmw cha >69 6a.m Am>aua66m av ma.m Hm.a 95.4 aa.m whommmm came wouDOmlz am.m Hm.a mo.m 6H.m m>m mousomuz mm.m 0N.0H mm.m om.m. hv.N ow no.6 mo.m om.m mm.m Hm.m mH Hm.m Nm.N «m.H mo.m mv.N m ov.e mm. Nm. Nb. Hm. mm.H 0 H062 em.v No.6 NH.m mm.m m>6 wouSOmlz No.6 Nmum mm.m Hm.v mm.m ow mm.m Ho.> Nw.h Nw.m mm.¢ mH mN.v v>.N Hm.N om.m mv.m m om.¢ Nm. mm. mm. mm. we. 0 6m0uo6H 2mm muommmm cH6E .m>6 Homlwmz wmzn6sw< 6mm: Houucou 60Hp6ucmeu6m 6>HuH©p¢ 6>HDH66< >69 . mouDOmIz mo >60 n . UTECflHCOU .bH anmfi 74 Silage dry matter content (Table 18) was not altered by the addition of.2% nitrogen in the form of urea, aqua-NH4 or NH4-solution. The disaccharide and mineral additives gen- erally increased (P<<.10) silage DM compared to no additive. This was probably a reflection of the amount of additive in- corporated into the silage since they were added at approxi- mately 3% of silage dry weight. Lopez gt El; (1970b) found similar increases in silage DM when they added corn at simi- lar levels. CaCO3 and NaHCO3 treated silages tended to be lower (P<<.10) in dry matter and higher (P<<.05) in acetic acid than silages with added sucrose, lactose, or NaCl. It is probable that acetic acid was volatilized during oven dry- ing and resulted in a lower apparent silage dry matter. Day zero dry matter values tended to be higher than all others. Trends in DM content as affected by N-source and day of fermentation for the 3 X 8 X 4 factorial analysis (Appen- dix Table 4) were similar to those reported above. All treat- ments containing sucrose and lactose tended to be higher (P—<.10) in DM than those without disaccharide. Here again, the dry matter of the additive incorporated into the silage was most likely responsible for this increase. CaCO3 in com- bination with disaccharide amounted to about 6% of the silage dry weight. Silage total nitrogen (TN) as affected by N—source, mineral or disaccharide additive, and day of fermentation are presented in Table 19. As expected, control silage (TN) was lower (P<:.05) than that treated with nitrogen. Urea 75 A6060 uch :0 pwscHucoo 6H06BV o¢.mm no.5m Ho.>m mm.vm m>6 mousomlz mH.¢m oo.mm oo.mm om.¢m OH.Hm ow Hm.mm mm.>m Ho.>m mm.mm N>.mm mH mo.mm mN.mm mm.>m mm.wm mm.mm m em.mm Nm.mm o>.mm om.hm oo.ov o>.mm o meMDDm mw.mm Hv.mm m>.mm mm.mm m>6 onDOmlz mm.mm 0H.mm oo.mm oo.mm om.>m ow NH.mm Hm.mm mm.¢m No.6m mm.vm mH m>.mm mm.mm wo.mm mm.mm Nm.mm m m mo.mm mm.mm om.mm om.vm om.>m oo.mm c 00062 ON.mm mo.mm mm.mm NN.mm m>6 mousomlz o>.mm om.Nm on.mm om.mm oo.mm ow HH.mm om.mm v¢.mm Hm.vm om.¢m mH mm.wm om.¢m om.mm mh.vm oo.wm m m mm.mm oo.mm om.>m om.mm ow.mm om.vm o oo6u mw.¢m mm.¢m mw.mm Nm.vm m>6 60050612 oo.mm o¢.vm om.mm o¢.Nm om.mm ow mm.vm hm.mm mo.mm mh.¢m Hm.¢m mH mm.¢m om.vm mm.vm NN.Nm mm.mm m mm.¢m om.mm oo.hm oo.mm om.mm ov.mm o HOMDCOO 20m muowmmw CH6E .m>6 Homl_mm AV0216590 6600 Hohucoo coHumucwEuwm 6>Hqu©< 6>HuH©©< >60 wousowlz 00 >60 0 6.6m6HHm cuoo mo ucmucoo uwuu6E >06 co coHumucwEumm 00 >66 UC6 .6>Hqu©6 .mousom ammOuuHc mo uommmm .mH 6HD6B 76 .66>H6H666 H6u6cHE no 66Hu6£oo6mH6 H6560 HH6 you mcoHu6>u6mno 6Hmch 6:6 HoHucoo now moHHm 6666HH056 EOHM 6:666 606 m6sH6> coHu6cHQEOD 666566609 .6m6HHm 0660 NH 66 m6>HuH666 66660 666 NN. 66 66666 coHHsHomlemz 6:6 vaI6sv6 .6666 5000 :6moHuHZ6 6 mo 1N6. 66 H662 6666x616 Hm.H 6H.mmao¢v No.mmHmHv mm.mmAmV mo.>m~ov muomuuw CH6E >60 HMb. A6>Huw666 my mo.om mm.mm mo.mm h>.mm 6006mmm cflme 6DHSOmIz 6H.hm HH.hm 06.0m mm.mm m>6 60050612 mo.bm om.mm om.mm 0H.mm om.mm ov mm.mm Hm.mm mm.mm m¢.mm ov.mm mH mm.om mm.hm hH.©m N¢.mm mm.mm m mm.om mN.wm ov.mm o>.mm ON.mm on.hm o HU6Z No.6m NN.NM «N.am No.6m m>m mousomuz Nw.mm 0N.mm om.hm on.mm om.hm o¢ ww.mm Hm.mm NH.om mm.mm mH.mm mH mm.hm mm.mm mo.mm 50.5m mm.vm m om.mm om.hm ow.mm om.wm ow.mm oo.mm o 6600060 mmm 6666mm6 cH6E .m>6 Homlvmm 6621650< 6600 HoHucou coHp6DC6Eu6m 6>H6H66< 6>HHH66¢ >60 6OHSOmlz 00 >60 0 .66scHucou .NH 6H06B 77 H6060 0x6: :0 66::H0:00 6H06av 64».H a>>.H mom.H Hma.H m>6 66050612 omm.H mom.H. Hmm.H w¢o.N Nmm.H ow Nmm.H 660.H Nvm.H Nmm.H om¢.H mH ON>.H mum.H nmm.H mam.H «HN.H m HNn.H mh6.H o>>.H HNN.H Nmm.H NN¢.H o 66000:m cam.H «mm.H H6H.N mae.H m>m 660506nz «mm.H mmm.H me.H H>H.N N66.H ow OHN.H mmm.H mmh.H hmH.N hme.H mH wom.H hum.H Nmm.H Hmo.N Hm¢.H m m mmm.H mNN.H omh.H mmH.N mmN.N mmm.H 0 00062 ONm.H omm.H HmH.N ovm.H o>6 60030612 MHm.H mwo.N. mmo.N me.N mum.H ow mmm.H NNN.H mom.H omN.N MHm.H mH mNm.H 6NN.H «mm.H mmo.N 5mm.H m m mew.H mm>.H mNm.H mum.H mmH.N mmo.H o 0060 moa.H mma.H Hom.m amm.H m>6 660sOmnz mNo.N NmN.H. m¢o.N Nom.N «Hm.H ow NNm.H 6mm.H chm.H NmN.N mNm.H mH wom.H mum.H Hoo.N 66H.N vn¢.H m omm.H mwm.H mmm.H obN.H mmN.N ovm.H o H000:o0 mmw 6006006.:H6E .m>6 HomlH0H66¢ 6>H0H66¢ >60 600306Iz 00 >60 0 .66m6HHm :000 00 0:60:00 :60000H: H6000 :0 :0H060:6E06m 00 >66 6:6 .6>H0H666 .:6mO00H: 00 600006 00 006000 mH 6H06B 78 .66>H0H666 H606:HE 00 66H06£0066H6 06000 HH6 000 6:0H06>06600 6Hm:Hm 6:6 H000 1:00 000 60HH6 6060HH056 5000 6:665 606 ~20 00 0:6006mv 660H6> :0H06:H0600 0:6506609 0 0o 2N6. 06 H062 0060260 NH 06 66>H0H666 06000 6:6 NN. 06 66666 :0H00H06Iv 22:6006 .6606 6000 :60000026 .606 HH6 2660 $2 606 6 0 th. NNN.HHNHV 66>.HHmHV mmh.HHmV 66>.Haov 6006006 :H6E >60 6mm. H6>H0H666 60 Hmm.H «mm.H neo.N 6m6.H 6006006 :H6E 60050612 mom.H H60.H mHm.H mmm.H 6>m 600206u2 66>.H mm6.H owh.H mwo.N mum.H ov N>>.H 666.H nah.H vnm.H mm¢.H mH vm6.H Hmh.H 66>.H NNN.H Hmm.H m mNh.H 666.H Hom.H mNh.H 6mm.H 66H.H 0 H062 mmm.H 60>.H mmm.H aae.H m>m 600506n2 mm>.H vmo.N. >>N.H 6Nm.H mom.H ow N65.H mvm.H Nm>.H HNm.H Hmv.H mH N66.H 66>.H om6.H mmm.H Nmm.H m 00>.H 6mh.H Nvm.H 66>.H oom.H wa.H o 6600060 206 6006006 0068 .m>6 Homlwmm 60216606 .6600 H000:o0 :00060:6E060 6>H0H66¢ 6>H0H66< >60 600:06I2 00 >60 0 .66::H0:00 .mH 6H06e 79 additions tended toward higher (P<<.10) TN than aqua-NH or 4 NH4-solution. A similar observation was noted in Table 10. Among disaccharide and mineral additives, the control result— ed in slightly higher (P‘<.25) silage TN than all others. This subtlety is attributed to a dilution of nitrogen concen— tration since the various additives tended to increase (P<<.10) silage DM. Consistent with this idea is the observa— tion in the 3 X 8 X 4 comparison (Appendix Table 4 and Table 19) that control silage with no additive tended toward slight- ly higher (P¢<.25) TN than those silages to which additives were incorporated. Silage total soluble nitrogen (TSN) values are pre- sented in Table 20 and Appendix Table 5. Control silage TSN was lower (P<=.10) than all other N-sources, while urea val— ues tended to be higher (P<1.25) than those for aqua-NH4 and NH4-solution for both factorial comparisons. Values on day 40 were similar to those mentioned above. There were no dif- ferences due to disaccharide or mineral additive and no signi- ficant interactions. The lack of TSN increase for control as fermentation time increased was similar to that observed and discussed with Table 11. Bergen EE.El; (1974) observed that TSN of control corn silage accounted for 36% of the total ni- trogen after only 12 hours of fermentation, but then changed slowly to 42% by day 20. TSN of control silage in this trial was 28% of the total nitrogen on day zero and also on day 40. As discussed earlier, it is possible that some proteolysis may have occurred before samples were frozen. The cool 80 H6060 0x6: :0 663:H0:00 6H06BV HHm. N06. N00. 0mm. m>6 600306I2 Hmw. 000. amp. 0mo.H mvw. 06 mom. N00. N60. 0mm. 00N. mH mmn. H00.H NHm. 00>. 00m. m mob. 0N0. wmn. mum. 0N0.H mmN. 0 6600036 ~60. 000. 6mm. 0mm. 6>6 000006I2 600. 060. 00>. mm0.H mNm. 00 000. 000. N06. >00. 00N. mH 60>. >00. mom. H00.H mmm. m m 000. rpm. mmm. 0N0. N00. NNN. 0 00062 00>. N05. N00.H mmN. m>6 60030612 mmh. H00. 000. 000. mom. 00 0Nn. 0mm. 0mm. 0mm.H mmN. mH 000. 000. 6H0. mm0.H 00m. m m 000. 6N6. H00. 00m. 00>. N00. 0 0060 com. 060. Nao.H mow. m>6 00000612 Hon. 0H0. 060., 000.H wmv. 00 000. omb. 000. 0N0. 06m. mH 0N0. 000. N00. NOH.H 00m. m >00. NHm. 06h. 0H0. 0mN.H mmv. 0 H000:00 mmm 6006006 :068 .m>6 H06|<02 <021630¢ 6600 H000:00 :00060:6E060 6>H0H660 6>H0H66< >60 . 60030612 00 >60 0 .6606HH6 :000 00 0:60:00 :60000H: 6H03H06 H6000 :0 :000 I60:6E060 00 >66 6:6 .6>H0H666 .600306 :60000H: 00 006000 .0N 6H06B 81 6H 06 66>000006 06000 0:6 66. 06 06006 :0003H0610mz 0:6 .66>000006 600060006600 00 H606:HE 06:00 HH6 000 6:0006>06600 6H0:06 0:6 H000 1:00 000 60H06 60600Hm30 £000 6:668 606 020 00 0:600600 663H6> :0006:00800 0:6506609 .606H06 swm0m 0o :66. 06 H062 0060x666 6216306 .6603 8000 :60000026 00H. 060.0000 666.06Hv 060.060 066.000 6006006 :068 060 006. ~6>000006 60 600. 660. 060. 666. 6006006 :065 60030612 600. 066. H06. 606. 0>6 60030612 006. 660. , 606. 006.. 006. 00 666. 606. 066. 000. N06. 6H 060. 666. 066. 600.H 006. 6 066. N66. 660. 660. 666. 606. 0 H062 666. 606. 666. 066. 0>6 60030612 600. 060. 666. 060. N00. 00 006. 606. 6H6. 000. H06. 6H 066. 066. 660. H06. 666. 6 N66. 006. 6H6. 660. 6H0. 0H6. 0 6600066 206 6006006 :06E.A.0>6 H0610mm 106216300. 6600 .H000:00.1:00060:6E060 6>00000¢ 6>00000¢ 060 60030612 , 00 060 n .6osc0ucoo .om 60660 82 temperatures and the anaerobic conditions established early by rapid evacuation of air from the experimental silos may have inhibited any further proteolysis. Water insoluble nitrogen (WIN) content of control corn silage (Table 21) was identical to that treated with urea, aqua-NH4 and NH4-solution. There is usually a higher final WIN content of NPN and especially ammonia treated corn silages when compared to the same silage ensiled without NPN additives. Bergen gt El; (1974) reported that WIN accounted for 58% of the total corn silage nitrogen after 20 days of fermentation. The WIN for control corn silage in the present experiment (Table 21) accounted for 72% of the total nitrogen after 40 days of fermentation. Fermentation over a 40-day period failed to appreciably alter WIN content of the various corn silage treatments. A slight increase in WIN content for control corn silage and the NaHCO3 treatment combinations was noted (Table 21 and Appendix Table 5); but, rather large standard errors of the treatment means due to lack of suffi- cient replication precludes any declaration of significance of differences. 83 06060 0x6: :0 063:00:00 6H06BV 066. 066. 606. 660.0 6>6 60000612 060.0 606. 000.0 600.0 600.0 00 600.0 066. 666. 060.0 000.0 60 666. 006. 066. 600.0 060.0 6 000.0 066. 660.0 666. 606. 660.0 0 6600006 000.0 660.0 600.0 000.0 6>6 60000612 060.0 006.0 000.0 060.0 000.0 00 600.0 660.0 000.0 060.0 000.0 60 1 000.0 066. 606. 060.0 660.0 6 6 660.0 606.0 600.0 000.0 060.0 000.0 0 00662 060.0 660.0 000.0 660.0 6>6 60000612 060.0 000.0 660.0 060.0 600.0 00 660.0 060.0 000.0 006. 000.0 60 000.0 000.0 006. 006. 666. 6 6 660.0 000.0 060.0 600.0 660.0 066. 0 0060 660.0 600.0 600.0 060.0 6>6 60000612 060.0 660.0 600.0 660.0 060.0 00 600.0 600.0 060.0 006.0 600.0 60 660.0 060.0 000.0 060.0 000.0 6 060.0 060.0 600.0 060.0 660.0 000.0 0 0000000 206 6006006.:06E. 0>6 H061 mm 002163m< 660D H000:00 :06060:6E060 6>00000< 6>00000¢ 06a ,_. 60030612 _, 00 >60 0 .606H06 :000 00 0:60:00 :600000: 6H03H06:0 06063 :0 :00060 6 1:66060 00 060 0:6 06>600006 0600306 :600006: 00 006000 .HN 6H060 84 .66>000006 H606:0E 00 600060006600 HH6 000 6:0006>06600 6H0:06 0:6 H000 1:00 000 60006 60600Hm30 5000 6:668 606 020 00 0:600600 663H6> :0006c00500 0:6506609 .606H06 06600 00 066. 06 H062 0060x600 6H 06 66>000006 06:00 0:6 66. 06 06006 :0003H061002 0:6 00216306 .6603 5000 :60000026 0mm. NmH.HAo0V NhH.HAmHv moo.HAmv HHH.HAOV muowmmw :065 060 600. 06>000066 60 600.0 000.0 000.0 000.0 6006006 0065 60030612 0HH.H Nmo.H 000.H vmo.H m>m mUHDOmIZ wHH.H 0NO.H NVH.H mmm.H Oho.H ow NNN.H mom.H th.H hNH.H mH.H mH H0m. mom. 50m. 0mm. NNO.H m me.H Nam. MOH.H omm. mmm. Hmm. 0 H002 NOH.H Nmo.H mmm. vma.H m>m wUHDOmIZ mmo.H 00H.H 0mH.H mmm. th.H 00 0mH.H mmN.H 00H.H NHN.H OMH.H mH 0mm. mNm. 00m. 0H0.H ¢NH.H m who.H ovo.H 0NH.H moo.H Ham. mMH.H o mmOuomQ 206 6006006 :065 .0>6 H061 mm 0mmnmmmm 660D H000:00 :00060:6E060 6>000000 6>00600¢ 60030612 00 >60 0 063:00:00 .HN 6H06B 85 Experiment 2. The pH values of corn silage of four maturities treated with four levels of ammonia and three 1e- vels of water are presented in Table 22. Increasing dry mat- ter percent (DM%) at harvest had the general effect of also increasing silage pH. The 28% DM maturity level resulted in lower pH (P<:.05) than 39 and 46, and 36 was lower (P<1.05) than 46% DM corn silage. Ammonia additions also increased silage pH with the control being lower (P‘:.05) than .72% added ammonia and the latter level being higher than (P‘1.05) the two lowest levels of added ammonia. A consistently high- er pH was noted at both levels of added water (.8 and 1.6%) than for the control (no added water). A significant DM X NH3 interaction (P<:.05) suggests that ammonia affects silage pH differently at the various stages of maturity (DM%). The DM and NH effects appear to be additive at 39 and 46% DM, 3 slightly additive at 36% DM, and at 28% DM the added NH3 had no affect. The DM X H20 interaction (P<:.05) can be explain- ed by the differences of pH within the 1.6 H 0 level with a 2 low mean of 3.71 at 28% DM and the high mean of 4.34 at 46%. The NH3 X H20 interaction (P<<.05) is mainly due to the mark- ed increase in pH observed for the three levels of ammonia addition to the 46% DM silage. The significant (P<<.OS) three-factor interaction was probably due to the abnormally high pH values of the 39 and 46% DM silage at .72% NH3 and .8 added H20. The change in pH of the 36% DM corn silage resulting from added ammonia was negligible and far different from that 86 Table 22. Ammonia treated corn silage pH after 40 days fermentation.a Dry Ammonia level (%) H20 DM% main matter _0% 0 .24 .48 .72 avg effects 28% 0 3.48 3.70 3.85 3.85 3.72 .8 3.60 3.78 3.85 3.88 3.78 1.6 3.52 3.70 3.80 3.82 3.71 3.74 avg 3.53 3.73 3.83 3.85 36 0 3.78 3.78 3.84 3.98 3.84 .8 3.85 3.88 3.88 3.90 3.84 1.6 3.88 3.85 3.82 3.99 3.86 3.85 avg 3.84 3.81 3.84 3.92 39% 0 3.75 3.99 3.85 4.14 3.93 .8 3.74 3.90 4.00 4.66 4.08 1.6 3.71 3.85 4.07 4.62 4.07 4.02 avg 3.73 3.91 3.98 4.48 46% 0 3.85 3.95 4.08 4.15 4.01 .8 3.89 4.13 4.08 4.22 4.06 1.6 3.99 4.12 4.22 5.02 4.34 4.13 NH3 avg 3.88 4.07 4.13 4.47 NH3 (%) main effects 3.74 3.88 3.94 4.17 ----------------------- SEN = .081 H20 (%) main effects 0 3.87 .8 3.84 1.6 3.99 a I I I I Treatment combination means are from duplicate SllOS. 87 of Experiment 1 (Table 5). However, the method of applica- tion was different, the levels of addition were somewhat lower and the experimental silos were opened once in this trial while those of Experiment 1 were opened and resealed several times. Huber gt El; (1973c) have observed that increased silage dry matter % and addition of ammonia raised silage p1 values. Other workers (Huber §£_§1;, 1974; and Huber and Santana, 1972) have observed pH values of 4.0 and above for ammoniated corn silage. The lactic acid content of ammoniated corn silage is presented in Table 23. Neither ammonia level nor level of added water had any overall significant effects on lactic acid concentration of corn silage. Maturity exerted an inhi- bitory influence on silage lactate with 28% DM higher (P<<.Ol) than 36, 39 and 46. There was a consistent but statistically non-significant decline with each incremental increase in ma- turity. There was a significant DM X NH3 interaction (P4:.05) due to the large difference in response to NH3 at the differ- ent dry matter levels. Within the 36% DM silage the three levels of ammonia each increased lactic acid compared to con- trols, with maximum concentrations at .48% NH3. Even though there was a consistent decline in lactic acid content from .48 to .72% NH there was no marked decrease in lactic acid 3' production at the slightly higher levels of NH3 addition as observed in Experiment 1 (Table 6) at 40 days fermentation. However, concentrations of total N were not high enough to 88 Table 23. Lactic acid of ammonia treated corn silage after 40 days fermentation.a Dry Ammonia level (%) H20 DM% main matter 0% 0 .24 .48 .72 avg effects 28% O 12.66 11.88 9.79 11.02 11.34 .8 12.63 14.18 12.22 12.82 12.97 1.6 13.26 9.70 14.84 19.95 14.44 12.91 NH avg 12.85 11.92 12.28 14.60 36% 0 4.74 9.18 9.44 8.35 7.93 .8 6.47 10.04 9.88 9.70 9.02 1.6 6.31 8.66 14.36 8.54 9.47 8.81 NH avg 5.84 9.29 11.23 8.86 39% 0 12.48 6.50 8.50 7.18 8.67 .8 9.77 8.41 4.84 6.16 7.29 1.6 10.51 8.97 5.02 4.39 7.22 7.73 NH avg 10.92 7.96 6.12 5.91 46% 0 6.04 6.53 6.44 8.56 6.90 .8 5.84 6.98 5.04 5.02 5.72 1.6 6.13 7.04 7.02 4.75 6.23 6.28 NH avg 6.00 6.85 6.16 6.11 NH3 main effects 8.90 9.00 8.95 8.87 (%) ----------------------- SEM = 1.60 H20 (%) main effects 0 8.71 .8 8.75 1.6 9.34 aTreatment combination means expressed as a percent of DM are from duplicate silos. 89 show severe decreases in lactate. Also, the method of appli- cation and frequency of sampling were different and may have influenced fermentation patterns differently. Various researchers (Beattie, 1970; Huber gt ElLI 1973c; Huber gt El;r 1974; and Huber and Santana, 1972) have noted modest to marked increases in corn silage lactate with additions of ammonia at ensiling time. Huber gt gt; (1973c) also showed decreased lactic acid (5.78%) in 35% DM corn silage treated with .66% added NH compared to 30% DM corn 3 silage treated with .33% added NH3 (10.54% lactic acid). Lopez EE.§l; (1970a), Geasler (1970), Johnson gt gt; (1967) and Huber gt gt; (1973c) have all shown that lactic acid con- centrations decrease with advancing silage maturity. The acetic acid content of the ammoniated silages at four stages of maturity is presented in Table 24. There was a consistent decrease in acetic acid with increasing maturity. The 28% DM silage tended to be higher (P«:.lO) than 36, 39 and 46. Ammonia tended to increase (P<:.25) silage acetic acid compared to the control. The effect of H20 level was negli- gible on acetic acid concentration. In the face of strong two and three factor interactions and a rather large SEM it is difficult to make definitive conclusions about the influ- ince of maturity and level of NH3 and H20 on corn silage ace- tic acid content. One can rather safely draw the conclusion, however, that acetic acid levels in corn silage are decreased with advancing maturity and elevated with incremental levels of ammonia up to .48 or .72%. Huber gt al. (1973c) showed 9O Table 24. Acetic acid of ammonia treated corn silage after 40 days fermentation.a Dry Ammonia level (%) H20 DM% main matter H20% 0 .24 .48 .72 avg effects 28% 0 2.83 3.07 4.60 3.40 3.47 .8 2.79 3.55 3.63 3.74 3.43 1.6 2.30 2.36 3.00 2.95 2.65 3.18 NH3 avg 2.64 3.00 3.74 3.36 36% 0 1.64 2.26 2.16 2.71 2.19 .8 1.83 2.62 2.08 2.24 2.19 1.6 2.92 2.46 2.86 3.10 2.83 2.40 NH3 avg 2.13 2.45 2.36 2.68 39% 0 .88 1.48 2.04 2.24 1.66 .8 1.22 1.68 2.62 2.45 2.00 1.6 1.31 1.38 2.04 2.30 1.76 1.80 NH3 avg 1.14 1.52 2.24 2.33 46% 0 1.21 1.16 1.72 1.80 1.47 .8 1.20 1.62 1.67 1.88 1.59 1.6 1.21 1.87 1.37 1.90 1.59 1.55 NH3 avg 1.20 1.55 1.59 1.86 NH3 (%) main effects 1.78 2.13 2.48 2.55 ----------------------- SEM = 1.90 H20 (%) main effects 0 2.20 .8 2.30 1.6 2.21 aTreatment combination means expressed as a percent of DM are from duplicate silos. 91 increased silage acetate with addition of ammonia and de- creases with advancing maturity. Total organic acid (TOA) content of ammoniated silage was reduced with advancing maturity of the corn plant (Table 25). Silage at 28% DM had higher (P‘<.05) TOA content than the other silages harvested at more mature stages of growth. Levels of NH3 and H20 had no consistent influence on TOA con- tent of corn silage harvested over the range of 28 to 46% dry matter. In general, NH3 caused an increase in TOA of corn silage at 28 and 36% DM and caused a decrease or no change in 39 and 46% DM corn silages. High acidity has been shown to depress intakes and growth of young calves offered corn silage gg libitum (Thomas and Wilkinson, 1973; Wilkinson EE.El;r 1975). The lower pH values (Table 22) and the higher concentrations of lactic, acetic, and total organic acids (Tables 23, 24 and 25) asso- ciated with 28% DM corn silage would suggest that reduced voluntary consumption would have occurred compared to higher dry matter and less acid silages. The reduced silage dry matter intakes reported in Table l and Figure 2 for lactating dairy cows of silages below 33% DM would support this hypo- thesis. The dry matter content of the ammonia treated corn silages is shown in Table 26. An attempt was made to equalize the dry matter content within the four maturity groups. Be— cause of the small amount of silage in each experimental silo, and since duplicate silos were processed conjointly, it was 92 Table 25. Total organic acids of ammonia treated corn silage after 40 days fermentation.a Dry Ammonia level (%) H20 DM% main matter H20% 0 .24 .48 .72 avg effects 28% 0 15.92 15.51 14.91 14.78 15.28 .8 15.80 18.18 16.28 16.96 16.80 1.6 15.98 12.61 18.17 23.35 17.53 16.54 NH3 avg 15.90 15.44 16.45 18.36 36% 0 6.74 11.98 11.85 11.28 10.46 .8 8.58 12.92 21.27 12.18 11.49 1.6 9.55 11.53 17.56 11.88 12.63 11.53 NH3 avg 8.29 12.14 13.90 11.78 39% 0 13.74 8.54 10.78 9.76 10.70 .8 11.88 10.38 7.74 9.12 9.78 1.6 12.14 10.67 7.35 7.04 9.30 9.93 NH3 avg 12.58 9.86 8.62 8.64 46% 0 7.54 8.06 8.28 10.54 8.60 .8 7.04 8.99 6.90 7.14 7.52 1.6 7.48 9.11 8.74 6.88 8.05 8.06 NH3 avg 7.35 8.72 7.96 8.18 NH3 (%) main effects 11.03 11.54 11.74 11.74 ----------------------- SEM = 1.68 H20 (%) main effects 0 11.26 .8 11.40 1.6 11.88 aTreatment combination means expressed as a percent of DM are from duplicate silos. 93 Table 26. Dry matter content of ammonia treated corn silage after 40 days fermentation.a Dry Ammonia level (%) H20 DM% main matter H20% 0 .24 .48 .72 avg effects 28% 0 25.40 26.88 26.48 27.12 26.47 .8 26.14 26.39 26.08 27.02 26.41 1.6 29.22 30.32 30.95 31.02 30.38 27.75 NH3 avg 26.92 27.86 27.83 28.38 36% 0 36.50 35.98 36.44 36.20 36.28 .8 36.58 35.87 36.54 37.10 36.52 1.6 34.00 35.59 36.24 26.76 35.65 36.15 NH3 avg 35.70 35.81 36.40 36.69 39% 0 39.64 40.17 40.14 40.33 40.07 .8 38.84 38.61 38.15 40.60 39.05 1.6 39.00 38.65 37.37 40.60 38.90 39.34 NH3 avg 39.16 39.14 38.55 40.51 46% 0 42.92 46.76 48.29 48.74 46.68 .8 43.30 46.82 50.18 47.18 46.87 1.6 43.80 47.68 45.44 46.53 45.86 46.47 NH3 avg 43.34 47.09 47.97 47.48 NH3(%) main effects 36.28 37.48 37.69 38.27 ----------------------- SEM = .418 H20 (%) main effects 0 37.37 .8 37.21 1 6 37.70 a ' . . . . Treatment combination means are from duplicate Silos. 94 difficult to obtain a completely uniform DM content within each maturity. It would have been most beneficial to have been able to mix the entire load of silage at each maturity before processing the individual silos. The differences in DM (P4<.01) between maturities were intentional. There ap- peared to be a true difference in DM content within NH3 level with zero NH lower (P<<.05) than .24, .48 and .72%. How- 3 ever, there were significant DM X NH3 (P 06030696 06. 66.0 66.6 66.0 66.0 66.0 60.0 020 00 600 6006 000606 66.0 66.6 66.6 66.6 66.6 66.6 66.6 020 00 66 6006 000060 60. 66. 66.0 66. 06. 66. 66. 600300660 06063 06. 66.6 66.0 60.0 66.6 66.0 66. 6063006 06063 66. 66.6 66.6 66.0 66.6 60.6 66.0 06000 020 00 my 66000002 66. 60.6 66.6 06.6 66.6 66.6 66.6 66 666006 66.0 6.66 6.66 6.66 6.66 6.66 6.66 0660060 060066 600 266 66. 66. 66. 60 66. 0000600 06630006600 60COEE¢ 6603 00000006 60030612 00 0060060 6.06000 600060060 60 060 6606006 :000 00 00000600600 06006600 .mm 6006B 112 .Amo.Vv00 006060000 606 00000606006 000000 6 0000606 000 60662 .oo0 x 006E06600I600\006E06600 00 06006 60 00060606060 .6060 06 000 006506600 060 6300 6>00 00 60660 006660060 66006> 0600069 .0 $120 6.66 6666 0666 0666 0066 6666 0660 0606 0666\60 666660 060063 0606 o o o o . o o o . Nuwmwm 66 6 66 66 66 66 66 66 606 66 66 66 66 66 06 66 060 6 0 0 0 6 606 066 666 666 666 666 666 666\60 0060000 0002 60.6 6.66 6.66 6.66 6.66 6.66 6.66 6.66 060 60660606066 6.60 6.60 6.60 6.60 6.60 6.60 6.60 666\60 206 66 66.6 66.66 66.66 66.66 66.66 66.66 66.06 00.06 066 60660606066 0.60 6.60 6.60 6.60 6.60 6.60 6.66 666\66 206 60. 66. 6m. 60 06. 6>00606z 6>000600 x002 MMCOEE¢ 060D H000COU 000060 606006 0000 6.6606006 0000 0606600 6000006 006 660: 060 6300 00 6600600 000063 0000 006 0060» 00600006000 0000 006 0002 .mm 6006B 113 added NPN) than for cows receiving the negative control, .5% added urea and .9% added ammonia rations. The remaining three silage treatments (1% urea, .3 and .6% NH3) tended to- ward (P‘<.lO) increased persistency of lactation when com- pared to the negative control. Milk fat percentages during the 70-day treatment period were higher for those silages with lower milk production, therefore yields of 4% fat- corrected—milk were similar for all treatments. Daily pro- duction of milk protein (Table 33) was maintained at higher (P6:.05) levels for the positive control ration followed by the two highest levels of NPN addition (1% urea and .9% NH3) to corn silage than for the remaining four silage treatments. Silage and concentrate dry matter intakes were not different (Table 34); therefore, the increased milk protein cannot be explained on the basis of higher energy intake per se. Closer examination of Table 34 reveals that more than 50% of the total daily crude protein for the positive control ration came from concentrates. This increase in the proportion of concentrate crude protein could explain the increased milk and protein production on this ration. Possible reasons are: l) more concentrate protein could bypass the rumen to be di- gested in the abomasum; and 2) an improvement of protein nu- triment of rumen microorganism gig increased essential amino acids and/or carbon skeletons for microbial protein synthesis. The greater concentration (P<<.05) of ruminal acetic, butyric and total VFA for cows on the positive control ration, Table 35, suggests enhanced rumen microbial production. It is of 114 .6060 O6 000 6300 6>00 0000 60660 006660060 66006> 06000696 66.6 66.6 66.0 66.6 004M 66.0 66.6 06006 66. 66. 66. 06. 06. 66. 60.0 60600660600 066. 66.0 66.0 66.0 66.0 66.0 66. 66.0 666006 0666\660 666060 0060000 60000 fl fl n6l6l...m NN.N. mmlm .6I6I..M 0600.0. 06.0 60.0 06.0 66. 66.0 66.0 66.0 60600660600 666. 66.0 66.0 66.0 66.0 66.0 66.0 66.0 666006 0066063 6606 00 66 60.60 00400. mmqmm 60.60 wmqmm 00400. mmqmm 06006 06.6 66.6 60.6 66.6 066. 66.6 66.6 60600660600 66. 60.00 66.60 66.00 66.60 66.00 66.60 66.00 666006 . 0666\666 666060 66 266 66. .66. .Immql 60 66. 6>00666z 6>000606 6000000 6600 0000000 000060 606006 0000 6.606006 0000 00 006006600 202 00 06006006 66 00606>0006 0060000 60000 006 060060 000 00 606000 .6m 60069 115 interest to note that blood urea—N values (Table 35) were highest (P<<.Ol) for the three rations which elicited the highest milk protein production. The crude protein of these same rations was also higher. The NPN in milk was not ana- lyzed separately so it is possible that some of the increase in milk crude protein was due a higher NPN uptake by the mam- mary gland. Another explanation might be greater recycling of urea back into the rumen to provide a more constant and adequate supply of nitrogen for the rumen microbes. The negative control ration contained 9.4% crude pro— tein and was obviously inadequate to sustain high levels of milk production. It did provide a "bench mark" for assessing the value of added NPN to corn silage rations in this experi- ment. Milk and milk protein yields were higher at all levels of NPN addition than those of the negative control. There were no detectable differences in milk yield due to source of NPN; however, cows consuming the higher levels of added nitro- gen tended toward higher milk yields. One might be concerned about the relatively high pH value for silage treated with .9% NH3 (5.14); however voluntary silage consumption was not adversely affected (Table 34). Other workers (Huber gt_§l;, 1973c; Huber, 1974; Huber and Santana, 1972) have demonstrat- ed milk yields from ammonia treated silages comparable to cows consuming iso-nitrogenous corn silage rations that were supplemented with preformed protein. Also ammonia has nearly always been superior to urea as a NPN additive to corn silage. Body weight gains (Table 33) were highest (P<<.Ol) 116 .Amo.uv0v 006060000 0000600000006 606 00000606006 000000 6 0000606 000 606620. .00600060x6 00 0663 0660 00 6060 006060000 030 0 00 060006000600 00 66000 .606006 060 6300 6>00 0000 60660 006660060 66006> 06000606 0.0 00 00. Smm 06.60 06.00 066.6 0666 0666 0666 006 066 066 66 660 600 0666 0606 0066 066.6 066.6 066.6 66. 66. 66. 6000000 06.60 06.6 0666 0666 066 066 000 000 0666 0666 066.6 066.6 60 66. $005 000 0666 066.6 6>006062 06.60 6 60 2.660: 60006 0666 6 00 .0006 06000 0000 m 00 .0006 0000000 om0 6 00 .0006 000000000 0mmm w 00 .0006 000600 . 0 000 m 0 000000 06000 6>000600 060606060 0000000 000060 606006 0000 6.6060606060 00000 006 06000 00 606006 0000 OH MCOMUMGGM MMCOEEM GEN @605 MO “Dwmmm .mm 60068 117 for cows consuming corn silages treated with .5% urea and .9% NH3, than for other rations. Persistency of milk production for these two rations was lower than for the other N—supple- mented rations, suggesting that cows consuming these rations were utilizing more energy for growth and fattening than for milk production. The lowest weight gain and the lowest milk production for cows consuming the negative control ration sug- gests that 9% crude protein is too low for optimum digesti— bility and/or utilization of the digested energy. Rumen fermentation parameters are presented in Table 35. The pH of the rumen liquor and ruminal concentrations of acetic, butyric and total volatile fatty acids (VFA) were greater (P«=.05) for COWS'On the positive control ration than for the other rations. This ration contained higher levels of natural or preformed protein which probably enhance over- all rumen fermentation. Propionic acid levels were higher (P<1.05) for .6% NH3 than for cows consuming silage with .9% added NH3. There is no apparent explanation for this higher level except that acetic was also higher for .6% than .9% add- ed NH3 suggesting enhanced fermentation within ammonia addi- tion for the .6% level. Total ruminal VFA was high for the .6% NH3 silage ration. This silage contained the highest content of water insoluble nitrogen and consequently more natural protein than other NPN treatments and this may have stimulated VFA production. Ruminal ammonia concentration for cows fed the var- ious control, urea and ammonia treated corn silage rations 118 cannot be reported. Unfortunately, ammonia levels were either not detectable in the laboratory or they were extreme- ly erratic. This was true for both days of sampling. Appa- rently, rumen samples may have been contaminated with saliva during the process of obtaining them by stomach pump. A ten ml aliquot of strain rumen liquor had been immediately mix with one ml each of 9 N H SO and a saturated solution of 2 4 mercuric choride, but ammonia losses still occurred. This failure in ammonia analysis could also have been caused by faulty sample handling or improperly mixed or weak reagents. Blood plasma urea nitrogen concentrations for the positive control and the two highest levels of silage NPN supplementation were greater (P<<.OS) than for the other treatments. A positive linear relationship was shown between the amount of NPN added to silage and plasma urea nitrogen. Also, the positive control ration (12.6% crude protein) caused similar elevations in plasma urea nitrogen to rations containing corn silage treated with 1% urea or .9% ammonia (14.8 or 15.0% crude protein). Experiment 2. Chemical composition of the four si- lages fed in the metabolism trial are presented in Table 36. Total N tended to be lower (P«<.10) and WIN was lower (P4<.05) for urea than for NH3 added at ensiling to corn silage. Am- monia added just prior to feeding did significantly increase (P<=.05) the pH of corn silage. This increase in pH was simi- lar to what has been reported by Huber 95 El; (1974) but not as marked as that reported by Wilkinson and Huber (1975). 119 .0060060 000 006 m0 0060x6v 606006 000 00 0060060 6 66 0666600x6 606 006 000060 060 600600000 606006 600 000 60660 606 66006> 06000606 66. 66.66 66.66 66.66 66.66 00000 000600000 0000 666. 666. 666. 066. 660.0 00600000 000000600 00063 600. 666.0 666.0 666.0 666. 00600000 0000006 00000 666. 666.6 606.6 666.0 660.6 00600000.06000 66. 66.6 66.6 66.6 66.6 0000 000000 66. 66.6 66.6 66.6 66.6 00 66.0 66.66 66.66 06.66 66.66 000000 000 Immml 0000 602 Ilmmmmlw 602 000000006000 0000660 06 06006 2 00000606 06 06006 2 606006 0000 .06606006 00060 6 x 0 039v 606606 0606000600 00 060 6606006 00 00000600000 06000600 .mm 60068 120 Silage dry matter intake was held constant at 1.8% of body weight and was by design equal for all treatments (Table 37). The ration usually was completely consumed by 8-10 hr postprandial. The silage to which ammonia was added at feeding was generally consumed more slowly than the other silages. Nitrogen intake was calculated to be equal but chemical analysis (Table 36) revealed lower average nitrogen contents for corn ensiled with ammonia and that treated with urea at feeding. Hence, somewhat lower (P-<.25) nitrogen, and ADF digestibilities were lower (P<:.05) for silages en- siled with ammonia and urea than for silage to which NPN was added at feeding. The reason for this difference is not read- ily apparent since intakes were not different. Dry matter digestibilities were lower than those reported by Wilkinson and Huber (1975) and those generally expected for corn silage (Bryant 35 al., 1966; Huber gt 20;! 1965; Johnson and McClure, 1968). The range in N digestibility for this experi- ment is similar to that reported by other researchers (Cash, 1972; Wilkinson and Huber, 1975) using fistulated steers. Huber (1975) observed lower ADF digestibility of NPN treated corn silage compared to control silage. Body weight changes were considered to be of little significance since the periods were of short duration and silage intake was also restricted. Nitrogen balance values tended to be lower (P¢=.25) for silages ensiled with NPN than for NPN added at feeding time. Urinary nitrogen as a percent of ingested nitrogen was lowest (P‘=.lO) for corn silage ensiled with ammonia, while 121 .606606 00006 0000 60660 606 66006> 06000696 66.6 6.66 6.06 6.66 6.66 066 z 00000600\6 00000000 60.6 6.06 6.66 6.66 6.66 060 z 00000000xz 00000 66.6 6.66 6.66 6.66 0.06 066 z 0000\0 00000 66.0 6.66 6.66 6.66 6.66 060 z 0000\2 6000000 66.6 6.66 6.66 0.60 6.60 00\66 0000000uz 666 066 666 060 666 00\66 060000 006003 6006 66.6 6.66 6.66 6.66 6.66 060 06.6 6.66 6.06 6.66 6.66 00600002 06.0 6.06 6.06 6.66 6.66 000000 000 06V 6000000060606 66 6.06 6.060 6.660 6.66 ‘ 00x60 00600000 66. 6.6 6.6 0.6 6.6 00\600 000000 606 606000 066 0000 |I6mz 0000 II602 6000000 00 00000 0 60000600 00 00000 z 606006 0000 6.6600 00 6000006 060006 0003 0000660 06 00 00000606 06 0606600 606006 0000 060 606606 0000000600 0000 00000000 0000000 00600000 000 0000000060600 000000 .66 00000 122 fecal nitrogen as a percent of ingested nitrogen was highest (P05.05) for silages ensiled with NPN. Route of nitrogen ex- cretion was different for time of NPN addition. Urinary ni- trogen as a percent of excreted nitrogen tended to be lower (P<=.10) and fecal nitrogen as a percent of excreted nitrogen was higher (P<=.05) for silages ensiled with NPN. The nitro- gen retained as a percent of that absorbed was not different (P4<.25) even though there was a tendency for more N-reten- tion from the silages treated with NPN at feeding. 'Rumen parameters are presented in Table 38. Strained rumen liquor pH was unaltered by silage treatment. There was a consistent decrease in pH with time after feeding corres- ponding to the general increase in ruminal VFA concentration. Acetic acid content of rumen liquor seemed to be lower (P<:.25) on all samplings for corn silage to which ammonia or urea were added at feeding. This may have been due to steers not con- aming those silages as rapidly as the silages ensiled with NPN. Compared to zero hr, overall ruminal acetic acid levels were 46 and 60% higher two and four hr postprandial, respec- tively. Ruminal butyric acid tended to be higher at two hr postprandial (P<:.25) for silages treated with ammonia or urea at feeding, and ammonia added at feeding did elicite somewhat higher (P<<.10) ruminal butyrate than urea. 'Ruminal valerate levels were increased with time after feeding, but even at four hr postprandial valerate accounted for less than three percent of the total ruminal VFA. There was a consist- ent increase in all of the individual VFA of ruminal liquor .606606 00006 0000 60660 606 606 00 oo0\0E 66 666660mx6 606 mm 0m6ox6 66006> 0600060 0006 123 m0. m.m0 6.m0 6.m0 0.00 6 66. 0.00 6.00 6.m0 6.00 m mm. 6.6 6.6 0.6 6.6 o 62I660D 606600 00.m 0.60 6.mm 6.6 6.6 6 66.6 6.0m 6.6m m.60 0.60 N m I I I I I o 02 0m.m mm 00 60 00 6 mm.6 00 M0 00 m m 06.0 m 0 m 0 o 6006 60060600 0.6m 660 60m 660 660 6 6.60 No0 mm0 m0 600 m 6.6 mm 06 m6 6m 0 6006 60000006 m.m0 060 600 mom 660 6 0.60 660 660 N60 M60 N 6.6 66 66 66 66 6 000000000 o.6m 60m 06m 666 606 6 6.0m 06m 66m man 006 m 6.60 mmm mmm 6mm mmm o 6006 000600 660. 66.6 «0.6 No.6 06.6 6 060. 06.6 06.6 66.6 6m.6 m 660. 60.6 60.6 60.6 m0.6 o mm 266 6600 Ilmmz 660D mmz 060606mm0600 6000000 06000 0006660 06 66066 2 00000606 06 @6666 2 60000 606006 0000 .6600 00 6000006 060006 0003 0000660 06 00 00000606 06 6606600 606006 0000 660 606606 0606000600 00 6060606060 606600 60000 606 000000 06006 .mm 6006B 124 with time after feeding. The total VFA concentration at four hr postprandial was twice that at zero hr. Rumen acetate at all samplings was higher (P‘=.05) and rumen butyrate at four hr postprandial tended to be lower (P<:.25) for silages treat- ed with NH3 or urea at ensiling compared to addition at time of feeding. Rumen NHB-N was too low to be detected just prior to feeding. This might be due to the feeding of steers only once daily and to limiting DM intake to 1.8% of body weight. Both ammonia and urea ensiled with corn silage elicited less CP<<.01) ruminal ammonia at two and four hr postprandial than NPN additions to control silage at feeding. This lowering of rumen NH3 should benefit the host animal by allowing a more constant supply of NH3 to be released for rumen microbial pro- tein sythesis. However, with only two samplings postprandial it is difficult to draw definitive conclusions concerning possible N utilization. Blood urea-N was lowest (P<<.05) four hr postprandial for corn silage treated with NH3 at en- siling which might indicate better utilization of NPN or may simply be a reflection of lower nitrogen intake. Obviously, the digestibility and nitrogen balance data indicate no advantage of treating silage with NPN at en- siling, or any advantage of NH3 compared to urea. In fact, the data suggest the reverse is true. On the ensiled treat— ments lower protein and ADF digestibilities accounted for about 50% of the decreased dry matter digestibility. Hence, a decrease in the digestibility of the starch fraction must 125 have also occurred. Silages were harvested from the same field but there may have been differences in ensiling condi- tions and rate of removal from the silo. Unfortunately, the supply of control silage was exhausted during the third per— iod and a different control silage was used for the remainder of the experiment. The supply of corn silage treated with NH3 and urea was also limited and had to be frozen prior to the beginning of period four and thawed at feeding. These procedural modifications did not seem to influence dry matter digestibility, because results for the fourth period were si- milar to the previous periods. Even though digestibility was depressed by ensiling with NPN, utilization of digested energy is obviously not changed as demonstrated, by Wilkinson and Huber (1975). These researchers added NH3 at ensiling or at feeding in a growth study with 235 kg male Holstein calves. Live weight gain tended to be greater and plasma urea—N at four hr postprandial lower CP~<.01) for NH3 added at ensiling. SUMMARY AND CONCLUSIONS Corn silage pH and lactic acid concentrations were simultaneously increased by NPN additions in the lactation trial. This observation strengthens the hypothesis that ammonia (and urea) extends fermentation by formation of the ammonium salts of lactic and acetic acid. Water insoluble nitrogen was higher for the .6% added NH3 than for the con- trol and urea treated silages. The practical significance of this recurring phenomenon has not been fully exploited but it should allow for greater utilization of NPN in dairy cattle rations by: l) reducing proteolysis of the natural corn plant protein; and 2) permitting higher levels of NPN to be fed, i.e. more urea might be included in the concen- trate with ammonia than with urea treated silages before the threshold of excessive ration NPN were reached. ‘Milk yield, expressed as persistency of lactation, was highest for the positive control ration, lowest for the negative control and intermediate for the NPN supplemented rati0ns. When expressed as 4% fat-corrected milk there were no differences in yield. In practice, therefore, to reduce feed costs, ammonia should be more extensively used to aug- ment crude protein and water-insoluble nitrogen levels of corn silage rations for dairy cattle. Rumen fermentation parameters suggest enhanced VFA production for the positive (soybean meal) control and .6% NH3 supplemented corn silage 126 127 rations. Plasma urea nitrogen levels were highest and simi- lar (15.7 mg%) for the positive control and the highest levels of urea and ammonia silage supplementation, even though the latter rations contained 20% more crude protein. Silages fed in the metabolism trial were the control, .5% urea and .3% NH silages of the lactation trial. Chemi- 3 cal analysis of four composited samples per silage revealed 60% more (P<<.05) water insoluble nitrogen for NH3 than urea treatment at ensiling. Nitrogen balance and digestibility parameters tended to be lower for those silages ensiled with NPN. This observation does not agree with previous studies and more research is needed in this are. Experiments that do not restrict silage intake and that are of longer duration are necessary. APPENDICES 128 06060 0x60 00 060000000 600600 6.6 6.0 0.6 6.00 0.60 0.06 0.66 6600060 0.6 6.0 0.6 6.60 0.60 0.00 0.66 6600 06 n 0060 6.6 6.0 6.6 6.00 6.60 6.60 0.66 0062 0.6 6.0 6.6 6.00 6.60 0.00 0.66 6600060 0.6 0.0 6.6 6.00 0.60 6.00 0.66 6 00006 0.6 6.0 0.6 6.00 6.60 0.06 6.06 0062 6.6 6.0 0.6 0.60 0.60 0.06 0.06 0060 6.0 6.0 6.6 0.60 6.60 0.00 6.06 0000000 6600 I I I I I I I 6600060 I I I I I I I 6600 06 n 0060 0.6 6.0 6.6 6.00 6.60 6.60 0.66 0062 0.6 6.0 6.6 6.00 6.60 0.00 0.66 6600060 6.6 6.0 6.6 6.00 0.60 6.00 0.66 6 00006 6.6 6.0 6.6 0.60 6.60 0.00 0.06 0062 6.6 6.0 6.6 6.00 0.60 0.66 0.06 0060 6.0 6.0 0.6 0.00 0.60 6.60 6.06 0000000 0000000 006 06 06 . 60 00 m m 0 0606000 00 600006 0000060060060 00 6060 0600060006600 606000002 .606006 0000 00 00.0 60006060060 00 000060060060 00 060 006 6>000©©6 0606000 00 600060006600 .06000000 00 600006 00 006000 .0 60060 x0006mm< .060006 030 0000 60660 606 600600 I000 000 66006> 0060x6v 00006>06600 600 6006660060 6006> 00006000000 006006600 0060 .066. 06 0062 0060x60 000063 06600 606006 00 60 06 06000000 6>000006 600060006600 00 0606000 0060 U 129 .000063 06600 606006 00 66. 06 06006 663 6600006 202 66000 600 0000 06000002“ 000. A6>000006 w 600006I20 060. 00600 0.6 0.00 6.6 6.60 6.60 6.00 0.06 6600060 0.0 6.0 0.6 6.00 0.60 0.00 6.06 6600 06 n 0060 0.6 6.0 0.6 6.00 0.60 6.00 6.06 0062 0.0 0.6 0.6 0.60 0.60 6.00 0.06 6600060 6.0 6.00 6.6 6.60 6.60 0.06 6.06 6 00006 0.6 6.0 0.6 6.00 0.60 6.00 6.00 0062 6.5 0.0 0.0 6.60 0.60 6.00 0.06 0060 0 6.0 0.0 0.0 6.60 0.60 6.00 0.06 0000000 006I 02 0.0 0.0 6.6 0.60 6.60 6.60 0.06 6600060 6.0 0.00 6.6 6.60 0.00 6.00 0.06 6600 06 0060 m.» 0.0 0.6 0.60 6.00 0.06 0.66 0062 m.» 0.00 6.6 6.60 0.60 0.00 0.06 6600060 0.0 0.0 6.6 0.60 0.60 0.06 0.06 6 00006 0.6 6.6 0.6 6.60 6.60 0.66 6.00 0062 6.6 6.0 6.6 0.60 0.60 0.60 6.00 0060 v 6.0 6.0 6.6 6.60 6.00 6.60 6.06 0000000 02 6000 Sam I 00 06 , m0 . 00 m m 0 0606000 00 600006 ,0000060060060 00 6060 0600060006600 606000002 .060000000 .0 60069 x0006mm< .060060 >00 606006 00 0060 I060 6 66 0666600x6 606 m0 0060x6 006 006 0006 0600600060x6 600 0000 606 66006> 0600060 066. 06 c6mo00000 006063 06600 606006 0o 60. 06 660600600660 6>000666 0660M 06.6 0:0000666 6 660so6uzv 66.0 00660 60.0 60.0 00.6 00 60.6 00.6 60.6 60 60.6 00.0 06.6 m 00. 00. 00. 0 6600060 06.6 00.6 00.6 00 00.6 06.0 00. 60 00.0 66.0 60.6 m 00. 00. 00. 0 6600006 0006 000060 000. 06>000006 6 600006I20 066. 06660 06.0 06.0 00.0 00 60.6 66.6 60.6 60 00.6 60.6 66.6 m 06.0 66.6 06.6 0 6600060 66.0 06.0 00.0 00 00.6 00.6 00.6 60 66.6 66.6 06.6 m 00.0 66.6 60.6 0 6600006 00 206. 006Ivmm 062 6000 6600 000060060060 MH60060 0060606060 600006 06000002 00 >60 0600600060xm .606006 0000 00 0060000 0006 000060 006 00 00 06000000 00 6600006 66000 006 6600060 00 6600006 6000 60060 00 006000 .6 60069 x000600< .06006E 000 606006 00 0060 I060 6 66 0666600x6 606 m0 0060x6 006 006 0006 0600680060x6 600 5000 606 66006> 0600069 .060. 06 060600000 000063 06600 666006 0o 60. 06 660606006600 6>000666 066mm 60.0 000000666 6 600006120 66.6 00660 66.00 06.00 00.0 00 00.6 00.00 00.6 60 00.6 NN.N 60.6 m 06. 66. 06. 0 6600060 00.6 06.0 00.6 00 06.0 06.6 «6.0 60 06.m 66.0 06.6 m 06. 06. mm. 0 6600006 60006 0006000 06009 606. 000000606 6 600006I20 060. 00660 06.0 60.m 06.6 00 00.0 60.0 66. 60 60. 60. 06. m 06. 66. 06. 0 6600060 66.m 00.6 06.~ 00 00.0 66.0 06.0 60 06. 66. 66. m 06. 06. mm. 0 6600006 0006 000600 EMWi 00610mm 002 6000 6600 000060060060 MH10060 0 060656060 600006 06000002 00 060 0600600060xm .606006 0000 00 0060000 0006 0006000 0600m 006 000606 00 06000000 00 6600006 66000 006 6600060 00 6600006 6000 0060 00 00600m .6 60068 0000600< 132 .uwuums mum mmmawm mo unwoumm m mm cwmmwumxm wum Amy umuume Mao ammoxm Ham 0cm oHflm Hmucmeummxm mco Seam mum mwsam> amasnma .Awm. um cmeuuwcv usmwmz ammum mmmafim mo ma um cquuomuoocfl m>fiufi©©m comma m mmm..c0wuflccm a m0u50muzv hmm. Hm.a 2mm. . Amway Amway HOmJ Hmw.a omh.a NH>.H mah.H H¢m.a mmm.H mmfi‘a Hom.H om.bm mm.vm Nw.hm om.mm om.mm m¢.hm mv.>m om.mm «mm vam.a omo.m Nam.a mmo.H mon.a Nhh.H mmh.a mmm.a Aw>flufiwcm a mousomnzv 0H.hm vm.mm mm.mm ov.mm om.mm wm.mm mo.mm om.o¢ ¢mz mama mmm.H hum.a mom.H NH@.H ¢mm.H omm.a ¢Hm.a Hmb.a om.hm 5H.mm oH.hm om.mm ov.mm mv.om mm.mm om.mm wwHD amp. wUMSOm :mmOuqu ow ma m o mmouomq ow ma m o mmOuozm cmeHuflc Hmuoa ov ma m o meuomq ow ma m o mucuosm unwouomv umuume >uo cowumncwEuwm MHmoumu numquMHmm mo awn Hmucweflummxm .mmmafim cuoo mo ucmucoo cmeuuwc amuOu cam unwouwm amuume hue co mwOHSOm cmmOuufic wmunu 0cm wmouuma uo mmOuusm msam moomu mo uommmm .w magma xfimcmmm< 133 .uwuums haw wmmawm mo unmouwm m mm cmmmwumxm mum Rwy umuuwe Mac ummoxw Ham 0cm oaflm Hmucwefluwmxm mco EOum mum mm:am>.umasnma .Awm. um cmmOuuflcv unmflm3 nmmum mmmaflm mo wa um mmumuomuoocfl m>flufiw©m nommn m mb¢. ACOfluflGGm a mOHSOmIZV 5mm. Amway v¢m. boo.H mwm. ow Nvo.H omN.H mHH.H mH mmm. mam. 0mm. m 0mm. mnm. mmm. o mmOuUmq mva.H 0mm. wvH.H ow mmm.H wmo.H omo.H ma Ohm. oao.H wbm. m mmm. hmm. mom. o mmOuosm z mHQsHOmcfl uwumz 0mm. ACOfluflUCm w mOHDOmIZV mVH. ”many hon. bow. cam. ow vmm. com. wow. ma vmh. «ah. vmw. m mmb. cam. ¢mm. o mmOuqu Nam. #55. cam. ow mom. ¢hm. mNm. mH mum. mmh. 0mm. m mHH.H Nob. th. o mmOuusm Z wHQDHOm HmuOB mmm I Homlvmm vmz msm< mmuD. newumucwEumw “Hmoumu numumEmumm mousom cmmOuuflz mo mmo Hmucmawuwmxm .wmmaflm auoo mo ucwucoo cmmOuuflc wansHOmcfl umumz 0cm mMQDHOm Have» no mwOuSOm cmeMuwc wmusu 0cm mmOuuma uo meHODm msam oomu mo uowmmm .m magma xflwcwmma Appendix Table 6. 134 Percent ammonia recovery as affected by silage dry matter and levels of added NH and H20.a 3 Dry Ammonia level (%) H20 DM% main matter H20% 0 .24 .48 .72 avg effects 28% - 99.0 88.2 75.6 87.6 .8 — 116.9 99.3 76.2 97.5 1. - 95.2 96.9 74.2 88.8 91.3 NH3 avg - 103.7 94.8 75.3 36% - 57.1 56.2 52.2 55.2 . - 110.9 66.7 56.5 78.0 1. - 94.2 55.9 627 70.9 68.0 NH3 avg - 87.4 59.6 57.1 39% - 46.1 55.3 45.4 48.9 . - 78.1 73.9 63.3 71.9 1. - 40.0 69.1 70.7 59.9 60.2 NH3 avg - 54.7 66.1 59.9 46% - 56.2 35.0 32.3 41.2 . - 26.8 30.8 28.3 28.6 1. - 114.9 98.5 67.9 93.8 54.5 NH3 avg - 66.0 54.8 42.8 NH3 (%) main - 78.0 68.6 58.8 effects H20 (%) main effects 0 58.2 .8 69.0 1.6 78.4 aTabular values for each treatment combination (t.c.) were estimated from Tables 26 and 27 using the formula O/E X 100: where, O = the observed t.c. the expected t.c. increase in nitrogen and E = increase in nitrogen assuming 100% recov- ery of the added N. BIBLIOGRAPHY 135 BIBLIOGRAPHY Abfarowicz, F., U. Grzeszczak-Swietlikowska and A. Truszynski. 1963. An attempt to appraise the value of maize silage with addition of nonprotein nitrogen substances - urea, am- monium sulfate and ammonia water. Agr. Sci. Ann. 81-8: 695 (Translated from Polish). Annett, H.E. and E.J. Russell. 1908. The composition of green maize and of the silage produced therefrom. J. Agr. Sci. 2:392. Baker, R.F. 1971. Black laver development - one way to tell when your corn is mature. Crops Soils 24:8. Barker, S.B. and W.H. Summerson. 1941. The colorimetric de- termination of lactic acid in biological material. J.B.C. 138:535. Barnett, A.J.G. 1954. Silage fermentation. Academic Press, Inc., New York. Beattie, D. 1970. The effect of adding a liquid suspension of anhydrous ammonia, minerals and molasses to corn silage at ensiling, on fermentation parameters and beef cattle performance. M.S. Thesis. Michigan State University, East Lansing. Bechdel, 5.1. 1926. Quality of silage for milk production as affected by stage of maturity of corn. Penn. Agr. Exp. Sta. Bull. 207. Bergen, W.G., E.H. Cash and H.E. Henderson. 1974. Changes in nitrogenous compounds of the whole corn plant during en- siling and subsequent effects on dry matter intake by sheep. J. Animal Sci. 39:629. Bothast, R.J., G.H. Adams, E.E. Hatfield, and E.E. Lancaster. 1975. Preservation of high-moisture corn: A microbial ev- aluation. J. Dairy Sci. 58:386. Bothast, R.J., E.E. Lancaster, and C.W. Hesseltine. 1973. Ammonia kills spoilage mold in corn. J. Dairy Sci. 56:241. Brady, C.J. 1965. Nitrogen redistribution during ensilage at low moisture levels. J. Sci. Food Agric. 16:508. 136 Britt, D.G. 1973. Effect of organic acids and non-protein- nitrogen on fungal growth, nutritive value, fermentation, and refermentation of corn silage and high moisture corn. Ph.D. Thesis. Michigan State University, East Lansing. Bryant, H.T., R.E. Blaser, R.C. Hammes and J.T. Huber. 1966. Evaluation of corn silage harvested at two stages of matu- rity. Agronomy J. 58:253. Buck, G.R., W.G. Merrill, C.E. Coppock and S.F. slack. 1969. Effect of recutting and plant maturity on kernel passage and feeding value of corn silage. J. Dairy Sci. 52:1617. Byers, J.H. and E.E. Ormiston. 1964. Feeding value of mature corn silage. J. Dairy Sci. 47:707 (Abstr.). Byers, J.R. and E.E. Ormiston. 1966. Feeding value of corn silage made at three stages of development. J. Dairy Sci. 49:741 (abstr.). Cash, E.H. 1972. Relationship of silage fermentation and additives to dry matter consumption by ruminants. Ph.D. Thesis. Michigan State University. East Lansing. Conrad, H.R. and J.W. Hibbs. 1961. Urea treatment affects utilization of corn silage. Ohio Farm and Home Res. 45:13. Conrad, H.R. and J.W. Hibbs. 1964. Use care when feeding urea. Ohio Farm and Home Res. 49:52. Conrad, H.R. and J.W. Hibbs. 1967. Urea-treated silage for dairy cows. Ohio Rep. Res. Div. 52:59. Coppock, C.E. 1969. Symposium: Dairy cattle feeding. Pro- blems associated with all corn silage feeding. J. Dairy Sci. 52:848. ‘ Coppock, C.E. and J.B. Stone. 1968. Corn silage in the ra- tion of dairy cattle: A review. N.Y. State College of Agr. Misc. Bul. 89. Conway, E.I. 1950. Microdiffusion analysis and volumetric error. Crosby Lockwood and Son Ltd., London. Cullison, A.E. 1944. The use of urea in making silage from sweet sorghum. J. Anim. Sci. 3:59. Daynard, T.B. 1972. Relationships among black layer forma- tion, grain moisture percentage, and heat unit accumulation in corn.. Agron. J. 64:716. Daynard, T.B. and W.G. Duncan. 1969. The black layer and grain maturity in corn. Crop Sci. 9:473. 137 Dexter, S.T., C.F. Huffman and E.J. Benne. 1959. Physical, chemical and biological principles in silage making. Proc. Michigan State University Silage Conference. p. 31. Dox, A.W. and R.E. Neidig. 1913. Lactic acid in corn silage. Iowa Agr. Exp. Sta. Res. Bul. 10. Dox, A.W. and R.E. Neidig. 1912. The volatile aliphatic acid of corn silage. Iowa Agr. Exp. Sta. Res. Bul. 7. Geasler, M.R. 1970. The effect of corn silage maturity, har- vesting techniques and storage factors on fermentation para- meters and cattle performance. Ph.D. Thesis. Michigan State University, East Lansing. Goffart, M.A. 1877. The ensilage of maize, and other green fodder crops. Trans. and Pub. by J.B. Brown. New York. Gordon, C.H. 1967. Symposium: Storage losses in silage as affected by moisture content and structure. J. Dairy Sci. 50:397. Gordon, C.H., J.C. Derbyshire and P.J. Van Soest. 1968. Nor- mal and late harvesting of corn for silage. J. Dairy Sci. 51:1259. Hanway, J.J. 1966. How a corn plant develops. Iowa State Univ. Spec. Rep. No. 48. Hawkins, D.R. 1969. The effect of dry matter levels of al- falfa silage on intake and metabolism in the ruminant. Ph.D. Thesis. Michigan State University, East Lansing. Hillman, D., C.N. Hansen, E. Linden, T. Bowerman, P. Thompson, L. Thompson and K. Sowerby. 1973. Protein content of corn silage treated with ammonia on Michigan farms. Dairy Notes: July, Cooperative Ext. Ser. Michigan State University, East Lansing. Hooper, T.H. 1925. Composition and maturity of corn. N. Dakota Agr. Exp. Sta. Bul. 192. Huber, J.T. 1975. Feeding NPN and NPN—treated silage to dairy cows. 2nd Annual Silage Symposium. Ann Arbor, Mich. Huber, J.T. 1971. The nutritive value for lactating dairy cows of corn silage harvested at different maturities and treated with urea. Proc. 6th Internatl. Zootec. Sum. Milan, Italy. Huber, J.T., N.A. Dutrow, D.G. Britt, R. Ledebuhr and C.M. Hansen 1973a. Addition of anhydrous ammonia to corn silage. Dairy Notes: Aug. Cooperative Ext. Er. Mich. State Univ., East Lansing. 138 Huber, J.T., G.C. Graf, and R.W. Engel. 1965. Effect of ma- turity on nutritive value of corn silage for lactating cows. J. Dairy Sci. 48:1121. Huber, J.T., R.E. Lichtenwalner and D.G. Britt. 1973b. Acid and urea additions to high dry matter corn silage for lac- tating cows. J. Anim. Sci. 37:296. Huber, J.T., R.E. Lichtenwalner, and H.E. Henderson. 1974. Direct addition of ammonia solutions to corn silage fed to dairy cattle. J. Dairy Sci. 57:263. Huber, J.T., R.E. Lichtenwalner, D.D. Makdani, and H.E. Hender- son. 1972. Influence of various organic acids on silage fermentation. J. Anim. Sci. 35:230. Huber, J.T., R.E. Lichtenwalner and J.W. Thomas. 1973c. factors affecting response of lactating cows to ammonia- treated corn silage. J. Dairy Sci. 56:1283. Huber, J.T. and O.P. Santana. 1972. Ammonia-treated corn silage for dairy cattle. J. Dairy Sci. 55:489. Huber, J.T. and J.W. Thomas. 1971. Urea-treated corn silage in low protein rations for lactating cows. J. Dairy Sci. 54:224. Huber, J.T., J.W. Thomas and R.S. Emery. 1968. Response of lactating cows fed urea-treated corn silage harvested at varying stages of maturity. J. Dairy Sci. 51:1806-1810. Huffman, C.F. and C.W. Duncan. 1954a. Corn silage as a source of the unidentified grain factor(s) needed for milk r production. Mich. Agr. Exp. Sta. Quart. Bul. 37:23. ~ Huffman, C.F. and C.W. Duncan. 1954b. The nutritive value of corn silage for milking cows. J. Dairy Sci. 37:957. Huffman, C.F. and C.W. Duncan. 1956. Comparison of silages 4 made from field corn (Ohio M 15) and silage corn (Eureka) } for milk production. J. Dairy Sci. 39:998. 5 Huffman, C.F. and C.W. Duncan. 1959. Corn kernels in feces of dairy cattle fed corn silage. Mich. Agr. Exp. Sta. Quart. Bul. 41:539. Huffman, C.F. and C.W. Duncan. 1960. Chemical composition, coefficients of digestibility, and total digestible nutri- ent content of corn silages. Mich. Agr. Exp. Sta. Quart. Bul. 43:261. Hughes, A.D. 1970. The non-protein nitrogen composition of grass silages. II The changes occurring during the storage of silage. J. Agr. Sci. 75:421. 139 Hunter, C.A. 1921. Bacteriological and chemical studies of different kinds of silage. J. Agr. Res. 21:767. Jenkins, M.R. 1941. Influence of climate and weather on the growth of-corn in USDA Yearbook of Agriculture. U.S. Govt. Printing Office. Washington, D.C. Johnston, J.F.W. 1843. On the feeding qualities of the natu- ral and artificial grasses in different states of dryness. High. Agr. Soc. Scotland. Trans. L:57. Johnson, R.R.. T.L. Bolwani. L.J. Johnson. K.E. McClure and B.A. Dehoritv. 1966. Corn plant maturity. II Effect on ‘ in vitro cellulose digestibility and soluble carbohydrate content. J. Anim. Sci. 25:612. Johnson, R.R. and K.E. McClure 1968. Corn plant maturity. IV. Effects on digestibility of corn silage in sheep. J. Animal Sci. 27:535-540. Johnson, R.R., K.E. McClure, L.J. Johnson, E.W. Klosterman and G.B. Triplett. 1966. Corn plant maturity. I. Changes in dry matter and protein distribution in corn plants. Agron. J. 58:151. Johnson, R.R., K.E. McClure, E.W. Klosterman and L.J. Johnson. 1967. Corn plant maturity. III Distribution of nitrogen in corn silage treated with limestone, urea and diammonium phos- phate. J. Animal Sci. 26:394. Jorgensen, N.A. and J.W. Crowley. 1972. Corn silage for Wis- consin cattle. Production, harvesting, storage, use in dai- ry rations. Coop. Ext. Programs A1178, University of Wiscon- sin, Madison. Kempton, A.G. 1958. Bacterial, biochemical and environmen- tal interrelations in fresh and ensiled forages. Ph.D. Thesis. Michigan State University, East Lansing. Klosterman, E.W. 1970. Urea for beef cattle. Ohio Report Res. Dev. 55:111. Klosterman, E.W., L.J. Johnson and R.R. Johnson. 1965. Com- plete silage makes economical beef ration. Ohio Report Res. Dev. 50:75. Knott, F.N., C.E. Polan and J.T. Huber. 1972. Further obser- vations on utilization of urea by lactating cows. J. Dairy Sci. 55:466. Lichtenwalner, R.E., J.T. Huber and C.N. Hansen. 1972. Ef- fect of form of ammonia addition to corn silage. J. Dairy Sci. 55:709 Abst. 140 Lopez, J., N.A. Jorgensen, H.J. Larsen, and R.P. Niedermeier. 1970a. Effect of nitrogen source, stage of maturity, and fermentation time of pH and organic acid production in corn silage. J. Dairy Sce. 53:1225. Lopez, J., N.A. Jorgensen, R.P. Niedermeier, and H.J. Larsen. 1970b. Redistribution of nitrogen in urea-treated and soy- bean meal-treated corn silage. J. Dairy Sci. 53:1215. Mabbit, L.A. 1951. The role of plant cells in the ensilage process: an approach to the problem. Proc. Soc. Appl Bact. 14:147. Michigan Agricultural Statistics. 1974. Michigan Department of Agriculture, Lansing. Miles, M. 1918. Silos, ensilage and silage. A practical treatise on the ensilage of fodder corn. Orange Judd Co., N.Y. Miller, W.J. and C.M. Clifton. 1965. Relation of dry matter content in ensiled material and other factors to nutrient losses by seepage. J. Dairy Sci. 48:917. Montgomery, M.J., H.A. Fribourg, J.R. Overton and W.M. Hopper. 1974. Effect of maturity of corn on silage quality and milk production. J. Dairy Sci. 57:698. Neidig, R.E. 1914. Chemical changes during silage fermenta- tion. Iowa Agr. Exp. Sta. Res. Bul. l6. Nesbit, D.M. 1882. Silos and insilage. A record of practi- cal tests in several states and Canada. USDA. Spec. Rpt. Noller, C.H., J.B. Warner, R.S. Rumsey and D.L. Hill. 1963. Comparative digestibilities and intakes of green corn and corn silages with advancing maturity. J. Animal Sci. 22: 1135 (Abstr). Owen, F.G. 1971. Silage additives and their influences on silage fermentation. Int. Silage and Res. Conf. p. 79. I Q . '_f o “fl".‘u. Owens, M.J., N.A. Jorgensen and H.E. Voelker. 1968. Feeding value of high dry matter corn silage for dairy cattle. J. Dairy Sci. 51:1942. Perry, R.W., D.M. Caldwell, J.R. Reedal and C.N. Knodt. 1968. Stage of maturity of corn at time of harvest for silage and silage and yield of digestible nutrients. J. Dairy Sci. 51:799. 141 Peterson, W.H., E.G. Hastings and E.B. Fred. 1925. A study of the principal changes which take place in the making of silage. Univ. Wisc. Exp. Sta. Bull. 61. Polan, C.E., J.T. Huber, R.A. Sandy, J.W. Hall, Jr. and C.N. Miller. 1968. Urea-treated corn silage as the only forage for lactating cows. J. Dairy Sci. 51:1445. Rench, W.E. and R.H. Shaw. 1971. Black layer development in corn. Agron. J. 63:303. Russell, E.J. 1908. The chemical changes taking place dur- ing the ensilage of maize. J. Agr. Sci. 2:392. Salas, P.J. 1971 Urea, ammonia and m-analog additions to corn silage rations for feedlot cattle. Ph.D. Thesis. Michigan State University, East Lansing. Schmutz, W.G., L.D. Brown, and J.W. Thomas. 1969. Nutritive value of corn silages treated with chemical additives for lactation. J. Dairy Sci. 52:1408. Sprague, M.A. and L. Leparulo. 1965. Losses during storage and digestibility of different crops as silage. Agron. J. 57:425. Stallcup, O.T., G.V. Davis, and D.A. Ward. 1964. Factors influencing the nutritive value of forages utilized by cattle. Ark. Agr. Exp. Sta. Bul. 684. Stanier, R.Y., M. Doudoroff and B.A. Adelberg. 1970. The Microbial World (3rd Ed.) Prentice-Hall, Inc., Englewood Cliffs, New Jersey. Thomas, C. and J.M. Wilkinson. 1973. Nitrogen and acidity as factors affecting the voluntary intake of corn silage. Proc. Brit. Soc. Anim. Prod. 2:67. Thomas, C, R.E. Wilson, R.J. Wilkins and J.M. Wilkinson. 1975. The utilization of maize silage for intensive beef production. II. The effect of urea on silage fermentation and on the voluntary intake and performance of young cattle fed maize silage-based diets. J. Agric. Sci. 84:365. U.S.D.A. 1972. Agricultural Statistics. U.S. Govn. Print- ing Office., Washington, D.C. U.S.D.A. 1974. Agricultural Statistics. U.S. Govn. Print- ing Office, Washington, D.C. U.S.D.C. 1969. Census of Agriculture. Graphic Summary. Vol. 5, part 15. U.S. Govn. Printing Office, Washington, D.C. 142 Van Horn, H.H., C.F. Foreman and J.B. Rodriguez. 1967. Effect of high-urea supplementation on feed intake and milk production of dairy cows. J. Dairy Sci. 50:709. Van Horn, H.H., D.R. Jacobson and A.P. Graden. 1969. Influ- ence of level and source of nitrogen on milk production and blood components. J. Dairy Sci. 52:1395. Van Royen, W. 1954. The Agricultural Resource of the World. Prentice-Hall, Inc., New York. Van Soest, P.J. 1964. Use of detergents in the analysis of librous fibrous feeds. II. A rapid method for the determi- nation of fiber and lignin. J.A.O.A.C. 46:829. Virtanen, A.I. 1933. (From Watson and Nash, 1960) Emp. J. Exp. Agric. 1:143. Watson, S.J. and M.J. Nash. 1960. The Conservation of Grass and Forage Crops. Oliver and Boyd. London. Wilkinson, J.M. and J.T. Huber. 1975. Addition of ammonia to corn silage: Effects on distribution of nitrogen, voluntary feed intake, animal growth and efficiency of feed use. J. Dairy Sci. In press. Wilkinson, J.N., J.T. Huber and H.E. Henderson. 1975. Acid- ity and proteolysis as factors affecting the nutritive value of corn silage. J. Anim. Sci. In press. Wise, G.H., J.H. Mitchell, J.P. LaMaster and D.B. Roderick. 1944. Urea—treated corn silage gs. untreated corn silage as a feed for lactating dairy cows. J. Dairy Sci. 27:649. Abstr. F Wittwer, S.H. 1974. Maximum production capacity of food crops. Bio-Science 24:216. Woodward, R.E. and J.B. Shepherd. 1944. Corn silage made with the addition of urea and its feeding value. J. Dairy Sci. 27:648. Abstr. Fl—v" . . s