RETURNING MATERIALS: IVIESI_} Flace in 500E arop to remove this checkout from LIBRARIES your record. FINES will be charged if book 15 returned after the date stamped below. W17 ME? > 10002 '94 3*“ ‘ r” L‘\ \w/T. 32/2 $.35 mam? M Mr V \7. .9" 93% 9‘44 £13m? MEASUREMENT OF COMPOSITION] OF GROWTH AND WSCLE PROTEIN DEGRADATION IN CATTLE By Farabee D. McCarthy A DISSERTATION Suhnitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Animal Science 1981 ABSTRACT Measurement of Composition of Growth and Muscle Protein Degradation in Cattle by Farabee D. McCarthy Experiment I The effect of 2 dietary energy levels on protein and fat gain during the growing (GRO) and finishing (FIN) phase of a feedlot trail was studies with 28 Limousin steers (254 kg starting weight). Steers were randomly allotted into 11 separate treatment (TRT) groups and each TRT group was fed the following diets: TRT-l, 8096 high moisture corn-corn silage (HVC-CS) during both GRO and FIN; TRT-2, l-MC-CS during GRO and all corn silage (CS) during FIN; TRT-3, CS during GRO and FIN; TRT-ll, CS during GRO and i-MC-CS during FIN. Protein gains were greater during GRO (P< .05) for TRT l with the trend to be greater for TRT 2 than TRT 3 and 4, and during FIN and TOT for TRT l and 4 than TRT 2 and TRT 3. Fat gains were greater (P< .05) for TRT l and TRT 2 than Farabee D. McCar thy TRT 3 during GRO, during FIN (P< .05) for TRT l and 4 than TRT 2, and during TOT for TRT l and ‘4 than TRT 3. ADC were highest (P <.Ol) for TRT 1 during the GRO, TRT l and 4 during PIN and TRT 1 during TOT. Experiment II Two genetically different types of steer calves were used in a two-year study to evaluate the effect of frame size on protein and fat deposition in cattle. ADG were greater (P <.05) for LG cattle during GRO and TOT while daily DVI intake was less for SM cattle (P< .01) during the GRO, FIN and TOT. Feed/gain was not different between frame types. LG cattle gained more protein/day during GRO, FIN (P< .05) and TOT (P <.Ol) than SM cattle. However, there was no difference in daily fat gain between frame types . Experiment I I I Eight steers of two genetic types (four each) were used to evaluate the effect of franc size on turnover rates of muscle proteins using 3-methylhistidine as an index. Analysis for creatinine (CRT) and 3-methylhistidine (BM-l) was performed . Farabee D. McCar thy LG cattle excreted more (P< .05) 3MB and CRT during the trial than SM. 3MH excretion slightly decreased while; CRT excretion increased with time for both treatments. 3MH and CRT excretion, expressed on a per unit of body weight basis, removed a frame effect. However, a decrease with time was seen with both CRT and BNH/BW. The 3M-l:(RT ratio tended to decline with age, while no frame effect was observed. The FBR and FSR was slightly lower for SM than for LG cattle with the FGR tending to be larger for SM than for LG. ACKNOWLEDGMENT The author wishes to express his deepest appreciation and gratitude to Dr. D. R. Hawkins for his guidance and encouraganent throughout the duration of the graduate program. Appreciation is also expressed to Dr. W. G. Bergen for his valuable cousel and constructive advice in designing same of these studies. In addition, the author is deeply grateful to Dr. H. A. Hennanan for his understanding and availability during these doctoral studies and for his advice and review of thisrnanuscript. Sincere thanks is also extended to Dr. A. M. Pearson for his conments and critical review of this dissertation. Sincere gratitude is extended to Dr. R. H. Nelson, Chainnan of the DeparUnent of Anhnal Science for providing necessary financial assistance and research facilities. A sincere thanks to Dr. W. T. Magee for his understanding and statistical advice in preparation of this dissertation. I also wish to extend a very special thanks to my fellow graduate students, for their intellectual sthnulation, aid in collection of sanples and of course for being friends. I would like to thank my beloved parents, Mr. and Mrs. William McCarthy, for their love and confidence in me. I only hope to repay to than everything they have done forlne duringlny life. Most of all, I wish to express my deepest and heartfelt thanks torny loving and beautiful wife Joy. Her love and support has been a corner stone for any success that I have gained or will ever gain. ii TABLE OF CONTENTS LIST OF TABLES . . . . . . . . . . . . . LIST OF FIGURES . . . . . . . . . . . INTRODUCTION . . . . . . . . . . . . . . . . . . . LITERATURE REVIEW . . . . . . . . . . . . . . GROW/TH OF MAJOR BODY TISSUE . . . . BODY C(MPOSITIW METHODS FOR MEASURING GROWTH . . Serial Slaughter Techniques . . . . . Whole Animal Chemical Analysis . . . . . 9-10-11 Rib Section Separation Specific Gravity . . . . . . . Live Annual In vivo Predictions . . Potassiun 40 Counting . . . . Antipyrine Dilution . . . . . . . Isotopic Dilution . . INFLUENCE OF CATTLE TYPE AND ENERGY LEVEL ON PERFORMANCE AND COMPOSITION! OF GROWTH . . PROTEIN TURNOVER IN THE INTACT TISSUE . . . . . MJSCLE PROTEIN TURNOVER IN SKELETAL MUSCLE . . Honnonal Effect . . . . . . . . . . . Growth Honnone . . . . . . . . . . . . . . . Insulin . . . . . . . Anabolic Steroids . . . Glucocorticoids . . . . . Thyroid Honnones . . . . . . Nutritional Effect . . . NT -METHYLHISTIDINE AS AN INDEX FOR MJSCLE. DEGRADATION . . . . . . . . . . . . . . . . OBJECTIVES . . . . . . . . . . . . . . MTER I AL m WTl-ms O O O O O O O O O O C O O O O PROTEIN ACCRETICN AND COMPOSITION OF GAIN STUDIES Trial 1 - Energy Effect . . . . . . . . . . Experhnental Anhnals . . . . . . . . . . Experhnental Design and Rations . . . . Management Procedures . . . . . . . . . . Slaughter Procedures and Carcass Evaluation . . . . . . . iii Page viii Body Composition Determination Specific Gravity 9-10-11 Rib Section . Deuteriim Oxide Dilution Statistical Analysis Trial 2 and Trial Experimental Animals 3 - Frame Size E Experimental Design and Rations Management Procedures Slaughter Procedures and Carcass Evaluation Body Composition Determination Statistical Analysis MUSCLE PROTEIN DEGRADATION STUDIES 3-Methylhistidine as an Index of Muscle Breakdown . Metabolism and Reutilization Study Experimental Animals, Design, and Collection Procedures Scintillation Counting 3-Methy1histidine Excretion Studies H. o o 0 5h. 0 o o 0 Experimental Animals, Design, Ration, and Collection Urine Preparation and Analysis Creatinine Analysis RESULTS AND DISCUSSION BODY COMPOSITION ESTIMATES FEEDII‘K} TRIAL - ENERGY VARIAle Feed 1 ct Performance Body Composition and Carcass Parameters Composition of Gain FEEDIM} TRIAL - Animal Performance Body Composition and Carcass Parameters Composition of Gain 3-METHYLHISTIDINE AS AN BREAKDOVN IN CATTLE Reutilization of 3- Methylhistidine . EXCRETIQQ OF 3- METHYLHISTIDINE IN CATTLE - FRAME SIZE EFFECTS (DICLUS IOVS . APPENDIX . . LITERATURE CITED . iv FRAME SIZE VARIATION INDEx 1301i mscie'PfiotE N I Page 60 61 62 63 71 71 71 72 75 76 76 77 78 78 78 78 79 79 79 80 82 83 83 108 108 110 122 1‘15 M6 107 157 162 162 169 200 202 216 TABLE 10. 11. 12. LIST OF TABLES Page Experhnental Design for Studying the Energy Effect on Canposition of Gain (Trial 1) o o o o o o o o o o o o o o o o o 56 Rations Fed to Lhnousin Steers in Feedlot Study (Trial 1) . . . . . . . . . . . . . . 58 Experinmntal Design for Studying the Franc Size Effect on Canposition of Gain (Trial 2 and 3) . . . . . . . . . . . . . . . . . . 73 RatiOns Fed to Steers Varying in Frmne Size (Trial 2 and 3) O O O O O O O I O O I O O O 7# Relationships Between Carcass Specific Gravity, 9-10-11 Rib Separation and Deuteriun Oxide Dilution Techniques For Esthnating Body Canposition . . . . . . . . . . . . . . . . . 84 Energy Effect on Feedlot Perfonnance (Trial 1) O O O O O O O O O O O O I O O O O 109 Energy Effect on Bnpty Body Cunposition, By Period (Trial 1) . . . . . . . . . . . . 111 Energy Effect onPercentage of Enpty Body Protein and Fat (Trial 1) . . . . . . . . . . . . . 120 Energy Effect on Carcass Characteristics (Trial 1) O O O O O O O O O O O O O O O O O 121 Energy Effect on Daily Bnpty Body Gains, By Period (Trial 1) . . . . . . . . . . . . 123 Energy Effect on Daily Enpty Body Gains, by Phase (Trial 1) . . . . . . . . . . . . . . 131 Energy Effect on Bnpty Body Tissue Gains as Percentages of Bnpty Body‘Weight Gains, by Period (Trial 1) . . . . . . . . . . 137 13. 10. ISO 16. 17. ISO 19. 20. 21. 22. 23. 20. 25. 26. Page Energy Effect on Bnpty Body Tissue Gains as Percentages of Enpty Body‘Weight Gains, by Phase (Trial 1) . . . . . . . . . . . . . . 138 Frane Size Effect on Feeding Perfonnance (Trials 2 and 3) O o o o o o 6 o o o o o o o 147 Frane Size Effect on Enpty Body Cunposition (Trials 2 and 3) O O O O O O O O O O O O O O 148 Frane Size Effect on Carcass Characteristics (Trials 2 and 3) . . . . . . . . . . . . . . 156 Frane Size Effect on Daily Enpty Body Gains (Trials 2 and 3) O O O O O O O O O O O O O O 158 Frane Size Effect on Bnpty Body Tissue Gains as Percentages of Bnpty Body‘Weight Gains (Trials 2 and 3) . . . . . . . . . . . . . . 159 Urinary Excretion of Radioactivity in Beef Cattle Fallowing Intravenous Adninistration of C'B’NhthYlhiStidine o o o o o o o o o o o 163 Urinary Excretion of 3-Methylhistidine, Creatinine and Total Nitrogen in Cattle overtime O O O O O O O O O O O O O O O O O O 170 Relationship Between 3-Methylhistidine Excretion and Body Weight in Growing cattle O O O O O O O O O O OO O O O O O O O 177 Urinary Creatinine Excretion Per Unit of Body weight in Cattle . . . . . . . . . . . 180 Urinary 3-Methylhistidine to Creatinine Ratios in Growing Cattle . . . . . . . . . . . . . 184 Example Calculation of Muscle Protein Turnover From Urinary 3-Methylhistidine Excretion in Cattle . . . . . . . . . . . . 187 Muscle Protein Degradation in Cattle Using 3-thhylhistidine as an Index . . . . . . . 189 Calculation of Muscle Protein Synthesis by Difference using Rates of Accretion and Degradation . . . . . . . . . . . . . . . . 191 vi Page 27. Fractional Breakdown, Synthesis and Growth Rates for Muscle Protein . . . . . . . . . . 197 vii 10. ll. 12. 13. 14. 15. LIST OF FIGURES A typical growth curve . . . . . . . . . . . Nbdel for a 2-pool open systan . . . . . . Kinetic equations for pool separation . . Enpty Body‘Weight - Specific Gravity versus D20 Dilution . . . . . . . . . . . . Enpty Body‘Water - Specific Gravity versus Dzo Dilution O O O O O O O O O O O O O O O O Bnpty Body Protein - Specific Gravity versus D20 Dilution . . . . . . . . . . . . finpty Body Fat - Specific Gravity versus D20 Dilution . . . . . . . . . . . . . . . . Percent Enpty Body Protein - Specific Gravity versus D20 Dilution . . . . . . . . . . . . Percent Enpty Body Fat - Specific Gravity versus D20 Dilution . . . . . . . . . . . . Percent Enpty Body Protein - D20 Dilution versus Rib Separation . . . . . . . . . . . Percent Bnpty Body Fat - D20 Dilution versus Rib Separation . . . . . . . . . . . . . . . Percent Bnpty Body Protein - Specific Gravity versus Rib Separation . . . . . . . . . . . Percent Bnpty Body Fat - Specific Gravity versus Rib Separation . . . . . . . . . . . Energy Effect on Bnpty Body Water Content . Energy Effect on Enpty Body Protein Content . . . . . . . . . . . . . . . . . viii Page 67 69 87 89 91 93 95 97. 100 102 10¢ 106 112 116 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. Energy Effect Energy Effect Energy Effect Energy Effect Energy Effect Energy Effect Energy Effect on on on on on on on Enpty Body Fat Content finpty Body weight Gain Bnpty Body Protein Gain Bnpty Body Fat Gain . . Daily Protein Gain . . Daily Fat Gain . . . . Protein Content of Gain Energy Effect on Fat Content of Gain . . Frmne Effect on Bnpty Body Water Content Frane Effect on Enpty Body Protein Content Frane Effect on Enpty Body Fat Content . Elhnination of Recovery of 14 14 C 34nethylhistidine . . C 34nethylhistidine . . . Daily 34nethylhistidine Excretion . . . Daily Creatinine Excretion . . . . . 3-Methy1histidine Excretion Per Unit of of Body Weight Creatinine Excretion Per Uhit of Body‘Weight Muscle Protein Degradation . . . . . . Muscle Protein Synthesis . . . . . . . . ix Page 118 125 127 129 133 136 141 144 151 153 155 166 168 173 175 179 182 186 193 196 LITERATURE REVIEW GlOoVTI-I OF MASK]? BODY TISSUES From the standpoint of animal production, the growth phenomenon from the time of conception to maturity, is an important aspect of animal agriculture. The major attempt in the study of growth of the animal is to produce carcasses that have muscle combined with desirable amounts of carcass fat and minimun bone. Growth according to Fowler (1968) can be looked at in two aspects. The first is measured as an increase in weight or mass. Hamnond (1952) defined growth as an increase in bodyweight until mature size is attained. Growth may also be described as an increase in mass of a body in definite intervals of time (Schlose, 1911). It is generally agreed however; that growth is more than just weight or mass gain. The second aspect involves changes in the form and composition of gain resulting from differential growth rates of the component parts of gain. At this time, no one definition of growth seems totally acceptable, but animal scientists generally prefer the description by Maynard and Loosli (1969). They defined true growth as an increase in muscles, bones and organs and should be distinguished from any increase resulting from fat deposition in adipose tissue. According 1 .1... 2 to their definition any increase in water, protein or ash content of tissue would constitute growth. In beef cattle we are prhnarily concerned with the growth and accretion of nmscle and bone plus accretion of fat, since these three tissues are thernajor canponents of thelnarketable carcass. Live weight change is easilylneasured by expressing it as weight gain per unit of time. However, the relative growth rate of specific tissues is Inore difficult to nwasure. “1 the past no reliable nwthods for obtaining quantitative neasuranents of tissues in live anhnals were used. Thelnost cannonlnethods for obtaining tissue growth patterns have anployed serial slaughter techniques by killing random samples of animals over a range of live weights. A. nonnal growth curve for live weight in cattle follows the configuration shown in Figure 1. The calf at birth, if all nutritional requiranents arelnet, will grow along a sigmoidal shaped curve showing acceleration at around puberty and deceleration asinaturity is approached. The growth of nmscle, bone and fat tissue does not coincide with the whole anhnal growth curve. As the anhnal grows, besides having a weight increase, there are adjusflnents in rates of growth of the tissues. The order of tissue growth is synonmnous If! all species (Brody, 1945). Tissues of nmst inmortance toward survival of the anhnal are fonned before birth. Thus, the order of tissue LIVE WEIGHT AGE Figure 1. A typical growth curve. 4 growth follows a sequential trend with tissues of more physiological hnportance being first to develop. The order of developnent follows an outward trend starting with the central nervous systan, progressing to bone, tendon, lnuscle, intennuscular fat and subcutaneous fat (Palsson and Verges, 1952a). However in the case of linflted nutrient supply the tissues are affected in reverse order. Due to the early developnent and growth of bone (McMeekan, 1959) and the later development and growth of Inuscle, thelnuscle to bone ratio at birthrnay be as low as 2:1. If growth patterns of the tissues are exanined, the rates of growth postnatally do differ (Berg land Butterfield, 1968). Postnatal bone growth is at a sJow steady rate (Johnson, 1974; Weiss et al., 1971) butlnuscle growth is relatively fast. This ultimately causes the nmscle to bone ratio to increase fran birth to nuturity. Fat canprises a relatively anall anount of the tissue in a calf at birth, but eventually it's growth rate increases so that in tenns of absolute amounts, it approaches or even surpasses that of muscle tissue. Muscle comprises a high percentage at turth, rises slightly, and then begins to decrease in percentage at the fattening phase takes over. Bonelnust reach a level of develonnent during the pre- natal life which allows it to function at birth; bone would therefore be called an early developing tissue. Muscle Inust also function at birth but not to the extent needed at 5 maturity therefore muscle would be a intermediate developing tissue. Fat on the other hand has minimal utility at birth and is a late developing tissue type (Berg and Butterfield, 1968; Berg et al., 1978 a,b,c,d). Research in sheep (Wallace, 1948; Palsson and Verges, 1952b) and swine (McMeekan, 1940) were similar to observations seen in cattle. These patterns of growth have been shown by rnany workers, including Callow (1948) and Berg and Butterfield (1968). The problem of partitioning growth arnoung body parts, still ranains Huxley (1932) defines the size relationship between the whole and its parts, mathematically by the use of the allometric equation of y=axb, where y is the size of an organ or part, x is body size and b is the growth coefficient of the organ or part. This equation was found to give a reasonable quantitative description is based on the assunption that relative changes in canponent parts during growth arelnore dependent on the absolute size of the whole rather than on the tinm taken to reach that size. The growth coefficient b represents the ratio of the percentage post-natal growth of y to the whole x and it therefore enables relative naturity to be expressed. The size of b is high when y represents a latelnaturing tissue, and low when y represents an earlyrnaturing tissue. 6 The allanetric equation was used to canpare the growth of nmscle, bone and fat relative to nmscle plus bone by Elsley et al. (1964) for lanbs and pigs, Berg and Butterfield (1966),1Mukhoty and Berg (1971) and Berg et al. (19783) for cattle. ‘The growth coefficient for bone in beef cattle was found to be low, less than 1.0;, forlnuscle intennediate, greater than 1.0;, and for fat high, fran 1.5 to 2.0. ‘The coefficients would substantiate that during post-natal growth, bone grows at a low rate, nmscle at an intennediate rate and fat at a high rate. The relative growth rates have been canpared between Inuscle, bone and fat, however the inechanics of the individualtissue growth should also be explored in this review. Bone develops either directly frun connective tissue or is perfonned as cartilage which undergoes gradual ossification. The pattern and rate of ossification may vary fran bone to bone depending on the strength required for that bone to function. Skull bones and consequently the volune of the cranial cavity, grow rapidly. Long bones grow in length at the epiphyseal plates. Prhnary growth in long bones postnatally is associated with increasing dianeters due to the vfunction of the periosteun, the connective sheath surrounding the diaphysis of the bone, laying down bone around outside of the shaft. As new bone is synthesized (H1 the outside, degradatin and resorption occurs on the inside to keep a fairly constant thickness. 7 Muscle tissue development and growth is quite different from bone or fat tissue. Mesoderm, the middle third of the primary germ layer in the embryonic stage gives rise to skeletal muscle tissue. During the embryonic stage, mesoderm cells referred to as undefined intermediate myogenic precursor cells, differentiate into presunptive myoblasts (Allen et al., 1979). These mononucleated presunptive myoblasts are replicating cells within the myogenic lineage but are unable to fuse or synthesize myofibrilar proteins. The differentiation of a presunptive myoblast through quantal mitosis, forms the mononucleated myoblast. These postmitotic cells contain all the essential machinery and are capable of synthesizing all contractile proteins found in mature muscle cells. There is however no DNA synthesis or mitotic cell division, so that once this stage is attained the quantity of genetic machinery will be altered only through satelite cell incorporation (Young et al., 1978; Young et al., 1979). The mononucleated myoblasts fuse with other mononucleated myoblasts to form new mulinucleated myotubes or may even fuse into existing myotubes. The myotubes accunulate myofibrilar proteins and are called myofibers or skeletal muscle cells (Strorner et al., 1974; Allen et al., 1979; Young and Allen, 1979). On the basis of muscle fiber nunbers, Burleigh (1976) suggested a two-phase pattern for muscle growth from embryonic to adult development. During the first phase, 8 hyperplasia predaninates where presunptive rnyoblasts or cells locked into being nmscle cells are actively replicating for a major portion of the embryonic developnent. During the second phase, hypertrophy and sane hyperplasia is occurring where the amount of protein per cell increases and cell replication is very slow. Winick and Nobel (1965) added a third phase where hypertrophy is duninate and hyperplasia is negligible. During early nmscle growth prior to fusion, hyperplasia is prhnarily responsible for the growth of tnuscle. After fusion, hypertrophy is thernajor contribution to the growth (Goldspink, 1972), with satellite cells likely increasing the DNA per muscle (Eversole, 1978; Young et al., 1978; Young et al., 1979). Fat cells arise franlnesenchmnal cells which are able to synthesize’ DNA. but not triglycerides. Although the precise pathway of histogenesis has not been clearly established, it is thought that nwsenchwnal cells differentiate into fibroblasts which in turn differentiate into preadipocytes. The preadipocytes fonn into lobular, gland like masses of epithelioid cells that develop into . brown adipose tissue or directly into ordinary white adipose tissue. Palsson (1955) stated that during the early developnent phase, adipose tissue has the lowest priority for nutrients, the reason for it's later nuturity. The 9 actual accretion of fat during the postnatal growth and developnent phase of the anhnal is dependent on the intake of energy over the required forlnaintenance. At the cellular level, increases in adipose tissue are achieved by either adipocyte hyperplasia or hypertrophy. Bell (1909) and more recently Simon (1965) reported the preadipocyte cell loses its capacity' to divide ‘when it begins to acculuate lipid droplets. This, however, is difficult to study since lipid accululation is initiated before the cell can be recognized as an adipocyte or fat cell. It is however generally agreed that during early developnent both hyperplasia and hypertrophy of adipocytes does occur. Dietary restriction does affect hypertrophy of the adipocyte (Lee et al., l973a,b) if canpared at a constant age, but by looking at weight constant canparisions no effects are seen. There was however an effect of dietary restriction on adipocyte number in several adipose depots. Lee et a1. (l973a,b) indicated that dietary restrictionlnay affect adipocyte number in intranuscular depot_but not in subcutaneous depots. This Inay suggest that adipocyte differentiations Inay be cunplete at birth in the subcutaneous depot, but not in the intranuscular location. This then reinforces the previous discussion that adipose tissue growth occurs fran both hyperplasia and hypertrophy depending on the tissue depot. 10 BODY COMPOSITION METI-DDS FOR MEASURING GRQVTH A variety of techniques have been used in attanpting to measure changes (Haecker, 1920; Hankins and Howe, 1946; Garrett et al., 1959; Byers, 1979) in body canposition during growth and developnent. The nmst commonlnethod of determining composition of gain is to determine the body composition of the animals at two or more points in their growth curve. Detennining body cmnposition of an anhnal can be done by two very generallnethods. The anhnals are either killed and the carcasses analyzed or 1 vivo techniques are used. Serial Slaughter Techniques Serial slaughter techniques, have been thelnost cannon Inethods to evaluate canposition and growth of anhnal tissue. In order to use a serial slaughter nethod several anhnals Inust be used. Since the anhnal is sacrificed, one is unable to evaluate growth of that animal at a later tinm in its growth and developnent. A second anhnalrnust be slaughtered at a later point and by difference one canineasure growth. One must assune that both animals were initially of the identical body canposition. Serial slaughter techniques are very expensive since nuny anhnals are needed to obtain any statistically significant differences. 11 Whole Animal Chemical Analysis One of the most reliable and accurate techniques for detennination of body camposition is the physical separation of tissues and then chanical analysis of the tissues. Early workers like Haecker (1920), Moulton et al. (1922) and others analyzed the total anpty body of cattle by sunning separate analyses for different parts and tissues. This technique is not widely used today prinmrily because it is laborious, and involves econanic loss of valuable carcass products. ‘Whole body analysis using physical separation of tissues has yielded a great deal of infonnation on the body canposition of cattle but cannot be a routine process. It should be an end point against which other less precise and indirect nethods of pmedicting carcass canposition can be tested. 9-10-11 Rib Section Separation Hopper (1944) suggested the rib cut as a predictor for canposition of the whole body. This was subsequently developed into a prediction fonnula for carcass canposition by' Hankins and Howe (1946). This technique, based on physical separation of the 9-10-11th rib cut into nmscle, fat and bone, has had widespread use for prediction purposes in cattle experhnents. The rib cut was chosen for its easy accessibility and high correlations relative to other cuts. 12 The relation ofrnuscle and fat in the rib cut to theinuscle and fat in the carcass were quite good with correlation coefficients of 0.85 and 0.93 respectively. However, there is considerable roan for error, particularly between dissectors and levels of fatness in the separating procedures. Specific Gravity The discovery of the principle of density is credited to the Greek scientist Archhnedes around 200 B.C. It is based on the fact that a body displaces a volune equal to its own. Esthnation of density can beinade fran theiArchhnedean principle. By weighing in air and weighing in water, carcass density can be detennined. For practical purposes the carcass can be considered a two-camponent systan, fat and fat-free tissue. Fat has a density of 0.90 andtnuscle about 1.0. A 0.002 change in density is about equal to a 1 per cent change in carcass fatness (Kraybill et a1. 1952). The application of bovin carcass density as a predictor of carcass fatness was first reported by Kraybill et al. (1952). Earlier work has been carried out in hunans (Behnke et al., 1942; meales et al., 1945; Brozek and Keys, 1951), rats (Da Costa and Clayton, 1950), guinea pigs (Rathburn and Pace, 1945) and pigs (Brown et al., 1951). Kraybill et al., (1952) were concerned with using density as a predictor of 13 the fat content of the live anhnal. No direct nmasure of body fat was detennined and carcass fat was estimated both fran the 9-10-llth rib cut using the prediction equation of Hopper (1944), and fran body water content using antipyrine inethod (Sobennan et al., 1949). This infonnation, along with the relationships anong the major chemical components of the bovine established by Reid et a1. (1955) was used to develop a canparative slaughter feeding trial procedure in which carcass specific gravity was the key to resolve body canposition (Garrett et al., 1959; Lofgreen and Otagaki, 1960; Meyer et al., 1960; Bieber et al., 1961). This procedure was useful in research where an esthnate of body canposition and energy storage is essential (Garrett et al., 1959; Lofgreen, 1965; Lofgreen and Garrett, 1968; Garrett and Himnan, 1969). The use of specific gravity or density in the prediction of carcass canposition was discussed by Pearson et al. (1968) and Jones et al. (1978), and results fran its use were presented by Garrett (1968). According to Garrett (1968), the standard errors of esthnate are too high to be very precise in predicting the composition of individual carcasses but in experhnents where replication is possible, the use of specific gravity can demonstrate differences between groups in body canposition. 14 Live Anhnal In Vivo Prediction The search for accurate indicators of carcass canposition on the live anhnal is a continuing process which has so far achieved little success. Such techniques would Inake it possible to follow changes in canposition in experhnental anhnals during growth without the necessity of slaughter. Breeders would find accurate live animal evaluation a great benefit when breeding and selecting superior lines of cattle. The objective in live anhnal appraisal should thus be to esthnate both weight and canposition of the carcass or even the weight oflnuscle in the carcass. The percentage of live weight which is Inuscle tissue is the hnportant consideration. Potassiun 40 Counting One unethod that has been used to predict body canposition in live anhnals is the whole-body counting of-a naturally occurring radioactive isotope of potassiun, K40. This has been used as a possibleinethod for predicting the anount of nmscle nass in the live anhnal (Zobrisky et al., 1959; Lohnan et al., 1966; Frahn et al., 1971; Daningo et al., 1972; Clark et al., 1976). “O 9 K has a long life (3 x 10 years) and it occurs at a relatively constant proportion of total potassiun. Potassiun is found in the body, prhnarily within the cells. Muscle tissue contains a high proportion 15 of the total potassitm of the body. Lohman and Norton (1968) found the potassium distributicni in the body of cattle to be 53.4 per cent in the standard trinmed lean, 12.4 per cent in the skeleton and 16.4 per cent in the gastrointestinal tract and contents. Neutral fat should have no potassiunlin it but sane will be present in fat depot because of blood and connective tissue. It is therefore reasoned that the anount of potassiun in the anhnal's body might relate directly to the anount of muscle tissue and that it should be possible to naasure the anount of K by ineasuring the 40K isotope. There are rather anall anounts 40 of K in the body thus K measurement is difficult. Sane of the technical problems in the measurement of “OK are associated with equipment calibration, background interference, repeatability and accuracy of measurement. Size and shape of animals being measured may affect the readings. There are other problems of a biological nature where we are not certain measured K in the body actually means. anything. Organs and tissues may have different concentrations and thus different contribution to the total body potassiun. There is also some evidence that the K concentration decreases in cattle and distribution is altered as live weight increases and the animal ages. 16 In spite of the problena with 40 K counting, the critical assessment of the usefulness will depend on how well it can predict totallnusclernass. Experhnents to date have shown reasonably good accuracy. It is a nondestructive technique and if accuracy can be achieved it would find a useful place in the research schane. Antipyrine Dilution Sobennan et al. (1949) presented arnethod forineasuring the total water content of the body 1 vivo based on the dilution of anitpyrine after its intravenous injection. Kraybill et a1. (1951) used this sane chemical dilution technique to esthnate body fat in 30 beef cattle fran the measuranent of total body water, with the assunption that the fat-free body contains 73.2 per cent of water. Fat and body water esthnates were canpared using specific gravity, 9-10-11 rib section and the antipyrine dilution technique. Kraybill et al. (1953) also looked at the application of antipyrine dilution in esthnating body fat in swine showing shnilar agreanents using specific gravity, fat separation, back fat thickness and antipyrine dilution. Whiting et al. (1960) discussed sane problans in the use of antipyrine, pointing out that although several early experhnents showed very good relationships between estimates fran the antipyrine technique and other body composition techniques (Kraybill et al., 1951; Kraybill et al., 1953; ‘ 17 Wellington et al., 1956) others have shown unpredictable occurrences of impossible values (Swanson and Neathery, 1956; Garrett et al., 1959). This indicates that there is sane differences in the behaviour of various antipyrines in how they equilibrate with the body metabolic pools, for example, with runen and tissue fluids. Isotopic Dilution The most cannon isotopes used in techniques to determine body composition are isotopes of hydrogen; deuteriun and tritium. Water containing one of these two isotopes, either deuteriun oxide (D20) or tritiated water (TOH) are con'monly used for tracing water pools in animals to determine body canposition. Deuterium, a stable isotope of hydrogen of atanic mass two is found in nature mixed with hydrogen of mass one in the ratio of 15 parts deuteriun to 100,000 parts hydrogen. In all natural substances in which hydrogen occurs this ratio is essentially the sane (Pinson, 1952). When deuterium canbines with oxygen to form deuteriun oxide (D20) a molecule of molecular weight 20 is obtained. Deuterium oxide has a specific gravity approximately 11 per cent greater than of pure H20 and it is this physical difference in density which has been employed in early measuring of deuteriun content of water using the falling drop technique (Sc‘hloerb et al., 1951; Hytten et al., (1962). When mixed with H20 the deuterium in D20 readily exchanges with the hydrogen of H20. 18 Tritiun is the radioactive isotope of hydrogen oftnass three. It has a physical half—life of about 11 years decaying with a soft beta particle to helium. Again tritiun acts very similar to H20 with more mass than the pure H20. The radioactivity is itsrnostlnarked physical characterisic fran the standpoint of its toxicity within biological systems and also from the standpoint of its assay in the study of such systans. Hevesy and Hofer (1934) introduced and pioneered the isotope-dilution technique bylneasuring and tracing the fate of heavy water in the hunan body. Moore (1946) later discussed total body water measurements, using deuteriun 23 42K. Gest et oxide, and total body solids, using Na and al., (1947) and Radin (1947) presented equations for isotope-dilution analyses and discussed the validity of these procedures. The use of these procedures for anhnal response measurements in terms of animal growth and the differential Haasuranent of body weight gains as pounds of fat,1nuscle, bone and water for body calorinatry (Reid et al., 1955; Garrett et al., 1959), and application for total body canposition with fann anhnals have been discussed (Pearson, 1965, Reid et at., 1955). The use of deuteriun oxide as alnarker for body water wasrnost popular between 1950 and 1958, it is interesting to note that the decline in its use coincided with the rapid development of liquid scintillation techniques that greatly 19 facilitated the counting of tritiated water. When first introduced, (Pace et al., 1947) tritiated water (TOH) had little advantage over D20 because both isotopes were difficult to measure. In the case of tritiated water, the marker was converted to gas and was counted in an appropriate insterent such as an electronic reed vibrometer. Thus, at first, the pattern of research with tritiated water duplicated that of deuteriun oxide. First work with deuteriun oxide and tritiated water centered around the characteristics of the compound as it pertains to the animal body and the total body water determination. Pinson (1952) looked at the properties of deuteriun and tritiLm as tracers of hydrogen in water exchange studies. Edelman (1952) looked at the use of deuterium oxide equilibration in body water and Haigh and Schnieden (1956) looked at total body water in rats. Most of the experiments using either deuterium oxide or tritiated water looked at total body water to estimate body composition (T111 and Downes, 1962; Panaretto, 1963; Panaretto and T111, 1963; Panaretto, 1964). Prediction of body canposition from deuteriun oxide and tritiun space in sheep by Searle (1970a,b). Foot and Greenhalgh (1970), Farrell and Reardon (1972), Trigg et al. (1974) and in cattle by Little and Morris (1972), Crabtree et al.(1974) all approached the ruminant water space as a single pool model. This combines the gut water with the empty body 20 water in to the total body water pool. The water in the digestive tract is not related to any carcass or anpty body canponents and introduces a large and variable error into prediction of anpty body canponents fran esthnates of total body water by isotope dilution. Byers (1979) developed a procedure for the separation of gut water fran anpty body water using a two pool system. Using tracer kinetics fonnulated by Shipley and Clark (1972), Byers used a deuteriun oxide dilution curve and separates it into two pools. This two pool systan has shown to be highly correlated to chanical analysis (r2 = 0.965) and with specific gravity (r2 = 0.952) by Byers, 1979. Along with the develoanent of the two pool systeniwhich produces a more precise and accurate prediction of body canposition in live anhnals, inethods for analysis of deuteriun oxide have also inmroved. Using vacuum sublhnation to isolate the water and deuteriun oxide, and an infrared spectrophotaneter to analyze the concentration Of DéO water (Byers, 1979 and Zweens et al., 1980), analyzing for deuteriun has becane less cunbersane. This along with the fact that deuteriun oxide is not radioactive has increased interest in this isotope in detenning body canposition i vivo. 21 INFLUEbCE OF CATTLE TYPE AND ENERGY LEVEL ON PERFORMANCE AND COMPOSITICN OF GROVTH The practice of growing out is widely utilized in the beef cattle industry to allow feeder cattle of small to Inediun frane size to developrnore protein in their carcass. There has been, however, some controversy in the animal science caTmunity as to whether composition of gain can be Inodified or altered with changes in nutrition. The concept that composition of growth is constant along with canposition at given weights, (Ried et al., 1968b) accepted by sane, dictates that the composition of growth cannot be nadified. Early research (Haecker, 1920; and Moulton et al., 1922) and then more recently (Callow, 1961; Henrickson et al., 1965; Byers, 1977, 1978, Harpster et al., 1978) docunented that substantiallnodification in canposition of growth can occur with changes in dietary energy levels. Whether or not cattle of all mature frame sizes will respond in canposition of gain and efficiency to varying levels of energy is of primary concern. The anall franed or canpact cattle were in great danand in the 50's and 60's while research during that time clearly indicated a much greater ability to gain for large franed 22 cattle (Stanley and McCall, 1945; Stonaker et al., 1952). It was also shown, however, that the feed conversion efficiencies did not necessarily coincide with the increased rates of gain in large frane cattle (Stonaker et al., 1952). Klostennan and Parker (1976) campared Angus and Charolais when fed either corn silage or corn grain rations to a sinfilar slaughter condition. Angus steers fed either high grain or high silage diets did not differ in carcass quality grade when fed to equal weights. However, Charolais steer fed a high silage diet graded two-thirds of a grade lower than those fed a high grain diet. Klosterman and Parker (1976) concluded that lower energy rations were of benefit more to early maturing cattle which consume more feed per unit of body weight. Crickenberger et a1. (1978) using Angus, Chianina crossbred, and PRHstein steers fed either high silage or high grain rations, looked at energy level and frame size effects on perfonnance and carcass traits. They found that high grain fed cattle, canpared to high silage cattle, had higher daily carcass gains, fatter carcasses and lower cutability. Daily protein and fat gains for high grain fed cattle were greater than high silage fed cattle. Daily protein gain tended to be greater and daily fat gain less for the larger cattle types canpared to average or snall franed cattle. 23 Byers and Ranpala (1979) showed shnilar results in that larger framed cattle on a high energy diet gained more protein per day than anal] franed cattle. They indicated that the "nutritional niches" for anal] and large size cattle ‘where rates of protein and fat deposition allow opthnal canposition of growth are provided by Inoderate energy diets for snall nature size cattle and high energy diets for anallinature size cattle and high energy diets for large franed cattle. Byers (1980) in a sunnary of their research on cattle feeding systans to regulate canposition of gain in cattle, indicates that at least for Hereford steers, daily rates of protein growth approachedtnaxhnun rates of 120g/day at about 1.0 kg daily anpty body weight gain. Other recent research docunenting sinfllar responses between rate and canposition of growth include studies of Woody (1978) and Garrett (1979). Both Woody (1978) and Garrett (1979) reported Inaxhnun rates of protein growth at between 0.95 and 1.00 kg daily anpty body weight gain Inay have a very strong relationship withinaxhnun daily protein gain andlnay be one of the controlling factors. Snith et al. (1977) canpared various biological types of cattle on a wide range of feeding reghnes. Cattle were either classified as anall type, at least five-eights British, Jersey, or Red Poll, or classified as large type, 24 one-half Brown Swiss, Charolais, Chianina, Gelbvieh, Limousin, Maine Anjou and large danestic dairy breeds. Five feeding reghnes ranging fran 2.18 Mcal ME/kg to 3.11 Mcal ME/kg were exanined. There were two or three slaughter groups per feeding reghne fran which regressions were developed to standardize data at a weight and canposition-constant endpoint. Live weight gains were as expected fran the energy density of the rations; however feed efficiencylneasured on a pen basis did not differ anong regimes or types. Composition of gain was inarkedly altered by reghne as was the effect of alllneasures of fat. Those cattle receiving the highest energy did show theinost fat gain of any feeding reghne in the trial. Byers and Parker (1979) conducted a study comparing cattle of varying inature size fed differing levels of nutrition. Cattle were fed either high energy orlnoderate energy diets. They reported that cattle on the high plane of nutrition deposited protein at 34 to 48 per cent and fat at 76 to 93 per cent faster rates than cattle fed the. inoderate plane of nutrition. This documented alnodification in canposition of gain resulting in a 19 per cent increase in percent fat in tissue gained with the high plane of nutrition. Large size cattle gained faster and werelnore efficient than smaller cattle on the shelled corn, high energy diet. 25 Prior et a1. (1977) studied the hnpact of dietary protein and energy on perfonnance and carcass characteristics of anpty body gain and carcass gain in 56 Hereford steers. Using as serial slaughter technique to detennine body canposition, slaughtering for steers per treannent at 341, 454, and 545 kg. The camposition of anpty body and carcass gain for a given weight was not affected by ration. Koch et al. (1979) presented data to indicate that fat deposition was linear with thne for all groups, although the rates depended on energy intake. The rates were 8.21, 2.08 and 1.29 kghnonth for the high, nadium and low planes of nutrition, respectively. The results suggested that steers are not progranned to synthesize protein first and then fat only with the ranaining enerSY; rather the level of energy intake and the age detennines how the ingested energy is partitioned into protein and fat synthesis. Other research would tend to agree with this suggestion (Guenther et al., 1965; Klostennan et al., 1965; Jesse et al., 1976; Perry and Beeson, 1976). Thus, the process of protein accretion and fat accretion occur shnultaneously during early growth, whereas in later growth, the rate of protein accretion becanes negligible (Bergen, 1974). It has becane evident through the review of the literature that there is considerable variation in results fran studies concerning the effect of energy and frane size 26 on canposition of gain, and perfonnance in cattle. Early research documented the increase in fat accunulation with higher energy levels (Haecker, 1920;1Moulton et al., 1922), as well asrnore recent research (Callow, 1961; Henrickson et al., 1965; Byers et al., 1976; Byers, 1977, 1978a; and Harpster, 1978) also concluding that there is an increase in fat storage at sinfilar carcass weights with high planes of nutrition. Jesse et al. (1976a), Guenther et al. (1965), and Reid et al. (1968) reported no effect of energy levels on carcass canposition. All this has aided in confusing the nutritionist about this area of research. At least a porthm1 of the inconsistency can likely be attributed to cattle frane sizes canpared, portion of the growth curves examined, degree of (Hfferences in energy intake levels, slaughter schedule, body canposition techniques and trial design. 27 PROTEIN TURNOVER IN THE INTACT TISSUE The naasuranent of protein turnover is frequently based on the uptake or release of labeled anino acids (Waterlow, 1970). One way in which protein turnover can be studied is by injecting a single dose of labeled anino acid into the organian. Since the turnover of the free anino acids in the body is rapid, the administered labeled amino acid will enter rapidly into tissue free anino acid pool and reach the peak value within a fewlninutes and then fall off rapidly to negligible levels (waterlow, 1969). It is therefore possible in theory, torneasure the rate of protein synthesis and protein breakdown (turnover) by observing the proportion of the adninistered labeled anino acid which is incorporated into tissue (synthesis rate) or the rate of disappearance fran the tissue (degradation rate). If the organisniis at a steady state in regards to protein turnover, the synthesis rate is equal to the degradation rate. If the tissue is gaining or losing protein, the rates of synthesis, rates of breakdown and the change in protein content of the tissue are all interrelated. The interrelation can be expressed by the sinmle equation: PROTEIN ACCRETION = PROTEIN SYNTHESIS - PROTEIN DEGRADATION. If two of the three canponents are known then the third can be calculated. 28 The naasuranent of protein turnover in the whole anhnal or an intact cell is canplicated by the fact that sane anino acids are reutilized. Reutilization of amino acids can occur within a tissue, intracellular; or between tissues, intercellular. There are also instances when proteins are secreted by one tissue and utilized as an anino acid source by another. With the reutilization of the anino acids occurring, the consequences of using a labeled anino acid as a tracer can lead to erroneous data in the detennination of protein synthesis or breakdown i vivo. Haverberg (1975) reviewed sane of the situations thatlnay occur that cause errors in esthnating turnover are: A). After the labeled anino acid has been incorporated into the tissue protein; it is released and can be reincorporated into the tissue. ‘This would lead to a loweredlneasure of the rate of loss of the label fran the tissue protein thus underestimating the rate of breakdown. B). The labeled anino acid can be incorporated into the protein of one tissue and released where upon it can be incorporated into protein of another tissue. In this instance, the extent of labeling of the later tissue protein would be dependent on the extent of both intracellular and intercellular recycling of the label. C). The entering labeled anino acid can be diluted out by blood and by the intracellular fluids. 29 The extent of reutilization of amino acids is dependent on age, diet, hormones, and various conditions that may affect the muscle protein turnover. Individual anino acids are reutilized at different rates and extents. It has been generally assumed that the shorter the experimental half- life obtained or the faster the estimate of protein breakdown is, the closer the value is to the "true" rate of protein degradation. In determining to what extent an experimental half-life approximates the actual rate of degradation, estimates of amino acid reutilization are made and the error from the reutilization is calculated. It appears that by the use of non-reutilizable anino acids, unambiguous protein degradation rates may beobtained. Measurement of turnover of tissue proteins 1 vivo has been reviewed by Neuberger and Richards (1964), Waterlow (1969), Schimke (1970), Waterlow (1970). With the relative lack of confidence in the available methodology multiple techniques have been used to look at degradation and synthesis rates of proteins. To illustrate some of the diversity in results of protein degradation studies a comparison of data can be used. Estimates of whole body protein turnover in adult man, using isotope compartment models, vary from 100 gm per day (Wu and Snyderman, 1950) to 300 gm per day (Waterlow, 1969; Gruner et al., 1961; Kassenaar et al., 1960). There are enormous discrepancies when comparing degradation rates by pulse 30 dosage of anhnals with a labeled anino acid and bytneasuring the rate of loss of label fran injected labeled protein. Fashakin and Hegsted (1970) found that rats given l(“C-anino acids, lost the label fran plaana with a half-life of about 18 days, whereas, injection of rats with pre-labeled plaana proteins yielded half-lives of 3 days or less (Anker, 1960). Shnilarly, Swick and Ip (1974) found that the rate of decay of radioactivity in albunin 'was 30%» slower after administration of 1“ 14 C guanidino-arginine than that obtained with C-carbonate. The longer esthnates are due to extensive reutilization of the labeled anino acid. Gan and Jeffay (1967) gave rats continuous infusion of labeled lysine or tyrosine in order to demonstrate and esthnate the degree of intracelluclar anino acid recycling. ‘When the plaana levels becane constant, they esthnated the specific activities of each of these amino acids in the plaana and the tissues. In the liver, the free anino acid pool achieved a specific activity no greater than 50%tof the systemic plasma levels, and when protein degradation was accelerated by a short period of fasting, the label in the liver free anino acid pool fell to about 10% of the plaana level. luuscle showed less extensive dilution with recycled anino acids and was not greatly affected by fasting. This extensive recycling in liver has been confinned by Stephen and Waterlow (1966), Waterlow and Stephen (1968) and by Schimke (1970), all of whom compared the rate of loss of 31 ltic-guanidino-arginine from liver protein with loss labeled of U-M C-arginine. This method of avoiding recycling by using l“C-guanidino-arginine depends on the exchange of the guanidino group of free arginine during the urea cycle. There are several drawbacks to the use of ltic-guanidino- arginine. Sane labeled free arginine will obviously escape so that 14 recycling of the C-label is not completely abolished. There is also the fact that the use of M C-guanidino- arginine depends on the presence of the urea cycle in the liver, any change in the activity of the area cycle will alter reutilization of the label. This dependence on the urea cycle in the liver makes the use of lI‘D-guanidino- arginine not applicable to other tissues. Ininuscle and ininost tissues, the reduction of recycling l("C-carbonate which labels can be overcame by using primarily aspartate and glutamate (Manchester and Young, 1959). This nathod is based on the uptake and release of 1“002 by the dicarboxylic acids (Swick, 1958) and has been used by Millward (1970a, 1970b), Perry (1974) and Swick and Song (1974) to look at protein turnover in liver andinuscle The reaction depends on transanination, occurring in nmst tissue and is therefore oflnore general use. There are labeled amino acids used to estimate muscle protein degradation. Young et al., (1971) used 1“ C-aspartic acid for the purposes of the in vivo labelng of muscle proteins. Use of this label largely overcomes the problem 32 of anino acid reutilization and hence allows ainore accurate estimate of rate of protein degradation in muscle cells. Swick and Song (1974) indicated that labeled glutanate and alanine can be used also to evaluate rates of protein degradation, but, reutilization of their labels does occur. Tyrosine, because of low natabolian in nmscle, and phenylalanine have also been used to evaluate protein turnover in nmscle however all labeled anino acid do have, to same extent, the problan of reutilization. An alternative to the single pulselnethod that does not provide absolute naasuranents of turnover of proteins, but rank theni in order of inagnitude, is the double-isotope technique described by Arias et al. (1969). In this procedure, two isotopic fonns of an anino acid, usually 3H- and l(‘C-leucine, are used to establish two tina points on 140 the curve describing degradation of the protein. leucine is first adninistered to an anhnal, then sane days later 3H-leucine is given to the sane anhnal just before it is killed. Proteins with rapid turnover rates such as those which are synthesized rapidly (high 3H) and degraded rapidly (low 14C) will have high 3HIMC ratios. Glass and Doyle (1972) used this procedure to give rate constants of degradation however they found that the interval separating the two isotope injectionsrnust be varied depending upon the range of half-lives being exanined. Pool (1971) was quick to point out however that occur due to reutilization even in this procedure. 33 In a situation in which turnover is in a steady state, degradation is equal to synthesis. This situation is not always occurring, so thatlneasuranent of synthesis rates are sometimes necessary. To obtain such an estimate after adninistration of a labeled anino acid, it is necessary to know the specific activity of the precursor pool. The rise and fall of the specific activity of the pool can then be used to correct for the radioactivity incorporated into the tussue protein. Integration of the precursor pool activity over short interva151nust occur in order to obtain a valid picture of the rapidly changing labeling of the precursor pool. An alternativeinethod would be a constant infusion of labeled anino acid, to attain a plateau level in the tissue. This nathod has been extensively used by Waterlow and Co- workers, (1968). Fran knowing the level of radioactivity of the plateau, it is possible to calculate rates of synthesis or proteins by observing the uptake of the label into protein. It is apparent that thernerits of both the pulse dose and the continuous infusion depends on the acceptance of the free amino acid pool of the tissues as the exclusive source of anino acids for charging tRNA in protien synthesis. If this is not the case or if it is only approxhnately so, these nathods lose precision in estimating rates of synthesis. 34 MUSCLE PROTEIN TURNOVER IN SKELETAL MUSCLE Honnonal Effect The endocrine systan influences nmscle turnover not only by the direct actions of honnones onlnuscle tissue, but also indirectly, by regulating voluntary food intake, and the subsequent distribution of nutrients between the tissues of the body in the fed and fasting state. There are canplex interactions between hormones both in the regulation of honnone secretion, and in the way they achieve their effect on the target tissue. Morgan and‘Wildenthal (1980) listed factors that are important in the regulation of protein turnover. Biological activity and availability of insulin, growth honnone, anabolic steroids, adrenal steroids and thyroid honnones areinost hnportant. Endocrine functions in the very young are not always the sane as in the post-weaning anhnal. The role of individual honnones in detennining growth and nutrient distributionlnay vary at different stages of development (Turner andlMunday, 1976). The hormonal control of fetal growth is poorly understood, although it is known not to be dependent on the fetal pituitary honnones. The role of honnones, both in the 35 adult and in the inmature animal, is primarily in protein synthesis stimulation however sane hormones are catabolic in nature. Bergen (1975) identified the interaction of hormones as being important at various points in protein synthesis. Gr owt h Hormone Early studies of the role of growth hormone in the regulation of muscle protein turnover have been reviewed by several authors (Korner, 1967; Manchester, 1970; Young, 1970; Kostyo and Nutting, 1973; and Kostyo and Reagan, 1976). Administration of exogenous growth hormone to intact sheep has produced a decrease in plasma concentrations of amino acids (Davis et al., 1970) indicating an increased uptake of anino acid by body tissue (Korner, 1967). Diaphram muscle fran hypophysectornized rats had a reduced rate of protein synthesis in vitro compared to normal muscle, whereas pretreatment with growth hormone in vivo or addition of the hormone in vitro stimulated both the transport of amino acids and the rate of protein synthesis (Waterlow et al., 1978). Goldberg et al. (1980) showed similar results in skeletal muscle. In muscles from normal rats sane workers have found that incubation with growth hormone has no effect (Manchester and Young, 1959; Kostyo 36 and Schnidt, 1962) while others have found that it stinmlates protein synthesis but not anino acid transport (Reeds et al., 1971; Turner et al., 1976). Growth honnone has been shown to affect anino acid transport, DNA and RNA.natabolian and ribosanal aspects of protein synthesis, especially ininuscle (Young, 1970; Young and Pluskal, 1977). Hjahnarson et al. (1975) have exanined the effect of growth honnone on protein synthesis in the perfused heart. Their data suggests that the rate of protein synthesis was lower in hearts fran hypophysectanized rats than in nonnal or honnonetreated anhnals. Judging fran the increased anount of ribosanal subunits in the hearts of the hypophysectanized rats, the initiation of protein synthesis was inmaired. Exogenous growth honnone has been shown to increase nitrogen retention (Davis et al., 1970) and increase carcass protein in sheep (Wagner and Veenhuizen, 1978). An understanding of thelnode of action of growth honnone onrnuscle proteininetabolisniis canplicated by the existence of growth-pranoting polypeptides under growth honnone control. These appear to be sornatornedin A and C, non- suppressible insulin-like activity and nmltiplication sthnulating activity; exerting an insulinlike action on their target tissue (Zapf et al., 1978). Furthermore, insulin and nutritional state inay Inodulate samatanedin generation (Yeh and Aloia, 1978; Phillips and Vassilouplou- Sellin, 1979). 37 Insulin A difficulty that is faced in understanding the mode of action of insulin on tissue protein metabolism is that this hormone exerts a large nunber of diverse effects in cells. Studies on insulin effects upon skeletal muscle have been carried out with much variation in both technique and results (Wool and Krahl, 1959; Jefferson et al., 1974; Frayn and Maycock, 1979). But, of the hormones involved in the. regulation of protein turnover in muscle, more is known about insulin than any other (Cahill, 1970; 1971, 1976; Manchester, 1976; Goldfine, 1978). Insulin regulates the uptake of glucose and also of many anino acids into muscle by stimulation of the A transport system. Insulin also regulates a nunber of intracellular processes, including protein metabolism. It is not known precisely how insulin is involved but a theory is that the insulin-receptor complex generates a second message at the cell surface which carries out all subsequent intracellular effects. Alternatively, it is possible that insulin itself enters the target cells (Goldfine, 1978) and that the hormone or product of insulin interacts directly with intracellular structures and protein synthetic machinery. The stimulation of muscle protein synthesis, by insulin, observed in vitro was confirmed in vivo. Hay and Waterlow (1967) showed that in whole animals, the rate of muscle 38 protein synthesis was depressed in experhnental diabetes. Kurihara and Wool (1968) and Sender and Garlick (1973) reported sinfllax results 111 their trials. Goldstein and Reddy (1967) showed an enhanced entry of anino acids into cells but not a direct effect on the synthesis of protein. Jefferson et al. (1974) showed a stimulating effect of insulin on protein synthesis and also showed a suppression of protein breakdown. Albertse et al. (1979) presented data to indicate a dranatic decrease in protein synthesis with diabetic rats when insulin levels were depressed. Nullward et al. (1976b) observed ininuscle of rats that RNA activity fell to very low levels when treated with streptozotocin. Wool et al. (1968) established that insulin is involved in the regulation of peptide chain initiation. These workers demonstrated a decrease in polysomes and an increase in inonaneric ribosanes in skeletal nmscle of alloxan diabetic rats. Generally insulin has been shown to increase inuscle protein synthesis however, a prelhninary study by Chrystie et al. (1977) indicated that exogenous insulin did not increase protein synthesis but decreased breakdown of protein in fetal lanbs. ThiSInay be another of the nany functions of insulin. 39 Anabolic Steroids There has been relatively little investigation into theinode of action of endogenous anabolic steroids or their derivatives on growth of skeletalinuscle and tissues, other than sex organs and accessory sex tissues (Young and Pluskal, 1977). Since skeletalinuscle isunore developed in the male than in the female, it is supposed that androgens might be responsible for myotrophic or anabolic action. Althoughinore is known about theinechanian of action of the estrogens (Chan and O'Malley, 1978), the sex steroids appear to affect similar biochemical processes in their target tissues. However, specifically whether the androgens and estrogens bring about their Inyotrophic effects in shnilar or dissinfllar ways is uncertain. Grigsby et al. (1976) showed an increase in protein synthesis in rabbits given exogenous testosterone, but, an increased plaana insulin would indicate no direct effect by testosterone. Sane effects of androgens onlnuscle however are known. Young (1980) reviewed androgen effects indicating that testosterone increases nmscle weight and protein inass, increases nitrogen retention, binds to cytosol protein receptors and that RNA synthesis increases in nmscle via an effect of nuclear chranatin. Mayer and Rosen (1977) concluded that androgens interfere with the binding of glucocorticoids to receptors ininuscle cytosol. 40 This is supported by the known antagonistic effect of anabolic steroids on the catabolic effects of glucocorticoids on muscle protein metabolism (Young and Pluskal , 1977) . Glucocorticoids Glucocorticoid hormones have long been known to have a general action on protein metabolism which is opposite that of insulin, decreasing the protein content of the carcass and increasing that of liver (Munro, 1964). Their overall effect is that of growth suppression and muscle wasting (Long et al., 1940). With respect to corticosteroids, they can directly inhibit DNA and protein synthesis and cell replication (Loeb, 1976; Baxter, 1978). Based on reviews (Loeb, 1976; and Baxter, 1978), glucocorticoids can inhibit growth hormone production and perhaps somatomedin production. It seems that this is not the only mechanism for their adverse effect on body protein gain. It is possible that steroids may affect uptake of substrates, such as glucose (Munck, 1971), which in turn affect growth or they may induce synthesis of inhibitory proteins that block synthesis of RNA. Young et al. (1968) showed that after injection of hydrocortisone, ribosomes isolated from rat skeletal muscle were less aggregated than those from control rats. The exact mechanism for glucocorticoid actions is not known. However it is known glucocorticoids result in reduction of muscle protein. 41 Thyroid Hormones An endocrine factor that is increasingly attracting more interest in the area of muscle protein metabolism is the iodothyronines. It is known that thyroidectornized rats have decreased protein synthesis in the gastrocnemius muscle in rats (Flaim et al., 1978b) and that treatment with thyroid hormone replacement enhanced synthesis. Young and Munro (1978) observed a reduced rate of muscle protein breakdown in thyroidectanized rats, and with thyroxine replacement there was an increase in muscle protein breakdown rate. Turnover of muscle proteins is more rapid in the presence of thyroid hormone. Since a net gain of muscle protein is achieved, and since both synthesis and degradation is enhanced, protein synthesis must be enhanced more than breakdown. Little is known about the mechanism of thyroid hormone action on protein metabolism. Thyroid hormones bind to several subcellular constituents, in particular, saturable nuclear binding sites have been demonstrated in several tissues (Sterling, 1979; Oppenheimer, 1979). The existence of T3-binding proteins in the cytosol is firmly established but their function has not been defined (Sterling, 1979). It has been suggested that they may help maintain a readily 42 available intracellular pool of hormone. Oppenheimer (1979) reviewed the possible mechanisms of thyroid hormone and suggests that the T3-nuc1ear receptor complex may stimulate directly or indirectly the formation of a diversity of mRNA sequences. Nutritional Effect Skeletaltnuscle has long been known to be a source of substrates for energy metabolism and of amino acids for essential protein synthesis in other tissue and organs. The studies of energy balance in fastinginan (Cahill, 1970; Young and Scrinahaw, 1971) serve as good examples of the contribution of muscle protein and extent of adaptation during reduced energy intake. In the fasting obese adult, as glycogen stores becane depleted,1nuscle protein becanes the source of glucogenic precursors from which glucose needed by the brain can be synthesized. The loss of proteins oxidized for energy clearly could not be tolerated for long. However, the brain switches fran glucose as an energy source to ketones as its najor fuel thus reducing the oxidation of nmscle protein. A shnilar adaptation can be produced by malnutrition, since a malnourished child loses less nitrogen than a child who is well nourished (Kerr et al., 1973). The provision of amino acids for gluconeogenesis and subsequent adaptation which occurinust result fran changes in the relative rates oflnuscle protein synthesis and breakdown. 43 The changes in RNA concentration ininuscle in response to various dietary treaflnents have been docunented byinany workers. Young and Alexis (1968) reported a loss of RNA franlnuscles in protein-deficient rats and Howarth (1972) clearly demonstrated that protein synthesis had priority over DNA synthesis wheninuscle growth was unpaired during a protein-deficient feeding period. As dietary levels decreased fran 24 per cent crude protein to 18, 12 or 6 per cent crude protein, weight gains and gastrocnaniUSInuscle weights decreased. There was a greater decrease in DNA) with RNA being intennediate to DNA and protein. Hill et al. (1970) and Cheek and Hill (1970) showed a reduction in protein synthesis during a protein-deficient diet while DNA synthesis is primarily affected with a calorie-deficient diet. Perhaps theinost detailed study is that of Spence and Hansen-Snith (1978), who investigated the effect of severe undernutrition on 13 ratlnuscles and showed a fall in the RNA/protein ratio along with nmscle responses. Millward et al. (1976a) presented data to indicate that during starvation in young and adult rats, synthesis rates decreased initially stopping growth. Then as synthesis rates continue to fall breakdown rates also decline. After nmscle takes over as the source of anino acids, taking over fran the liver and the gastro-intestinal tract, breakdown rates show a progressive increase. In the 44 adult rat the fractional breakdown rate of muscle, after 4 days of starvation are nearly twice the initial rate (Millward and Waterlow, 1978). Winick and Noble (1966) reported that the effect of calorie and protein restriction on cell nunber and/or cell size was dependent on the phase of growth. Rats subjected to early malnutrition had impeded cell growth and division. They concluded that undernutrition affects the permanent suppression of DNA synthesis more than RNA or protein synthesis and that it caused permanent growth retardation in animals when DNA accunulation is rapid. NT-METI'IYLHISTIDINE AS AN INDEX FOR MJSCLE DEGRADATIGNI It is generally known that the skeletal musculature is a major tissue in whole body protein metabolism (Young, 1970). Skeletal muscle represents a large reserve of protein that can be made available during periods of dietary stress. Nevertheless, there is little information on the mechanisms responsible for the maintenance of protein content in skeletal muscle and the contribution of protein turnover in muscles to the overall body protein metabolism under various nutritional, hormonal and nervous conditions, and in response to stress (Millward et al., 1976; Young, 1970; Young and Munro, 1978). There has been a growing interest in recent years in the study of protein 4S catabolism. The techniques used in these investigations have been primarily isotopic. However, the reutilization of the radioactively-labelled tracer anino acid, arising from protein catabolism, for protein synthesis yields underestimates of protein degradation rates (Poole, 1971; Glass and Doyle, 1972). An ideal index of protein degradation would be an amino acid which i: reutilized and reincorporated into proteins. Asatoor and Armstrong (1966) were first to suggest the measurement of the rate of excretion of 3-methylhistidine could provide an estimated of the turn-over of myofibrillar degradation. 3-Methylhistidine was first identified as a normal component of hunan urine in 1954 (Tallan et al., 1954), while Block and Hubbard (1962) found the anino acid in the urine of rabbits. The occurrence of 3-methylhistidine as a component amino acid in skeletal-muscle myofibrillar proteins of rabbits, was first demonstrated by Johnson et al. (1967) and by Asatoor and Armstrong (1967). Elzinga et al. (1973) later reported the positions of 3- methylhistidine in the anino acid sequence of actin of rabbit skeletal muscle. Further studies have demonstrated its presence in muscle proteins of other species (Haverberg et al., 1974; Haverberg et al., 1975; Holbrook et al., 1979; Nishizawa et al., 1979). It has been shown that the proportion of histidine molecules methylated in myosin 46 varies from one muscle of myosin Species to another, whereas the 3-methylhistidine content of actin is constant (Johnson et al., 1969; Kuehl and Adenstein, 1970). Huszar and Elzinga (1976) succeeded in isolating fran both rabbit and bovine cardiac myosin a tryptic peptide that contains the non-methylated histidine. 3-Methylhistidine is found in both actin and myosin and available evidence indicates that the methyl group is attached to free histidine after the formation of histidyl- tRNA (Haverberg, 1975t; Ward and Buttery, 1978). Hardy and co-workers (1970) demonstrated that S-adenosylmethionine was an effective methyl donor for the formation of 3- methylhistidine in muscle protein in rabbit skeletal muscle homogenates. This was confirmed by Krysik et al. (1971) in studies of the methylation of chick muscle proteins in vitro. Young et al. (1970, 1972) studied binding in vitro and in vivo of various labelled amino acids to tRNA and were unable to demonstrate a His( 3Me)tRNA. In conclusion, there is good evidence demonstrating that the methylation step occurs after the formation of histidyl-tRNA. The fate of adninistered 3-methylhistidine has been exanined by Cowgill and Freeburg (1957). They found that most (90%) of the radioactivity following aaninistration of 1“C methyl-3-MeHis to rats, rabbit, and chicken appears in the urine. Paper chranatography of the urine showed that unchanged 3-methylhistidine accounted for a major 47 proportion of radioactivity. Young et al. (1972) exanined the fate of orally or intravenously aaninistered lac-methyl NT-methylhistidine in rats and confirmed that there was a quantitative excretion of the label in the urine. Only trace levels of radioactivity appeared in the feces. This was later confinned in hunans (Long et al., 1975), in rabbits (Harris et al., 1977), in cattle (Harris and Milne, 1979; Harris and Milne, 1981) but does not seem to be true in sheep (Harris and Milne, 1977; Harris and Milne, 1980) or in swine (Mdlne and Harris, 1978; Harris and Milne, 1981). The physiological factors which control the accunulation of 3-methylhistidine in swine and sheep are not exactly known. However, in swine, the intravenous dose of labelled 3-MeHis is largely retained, if not exclusively, ininuscle where a considerable anount of non- proteinbound 3-methylhistidine exist (Harris and Milne, 1981). In sheep, Harris and Milne (1980a,b) reported evidence of a 34nethyhistidine dipeptide, balenine, present inlnuscle which ties up large anounts of 34nethy1histidine released duringlnuscle protein degradation. Because both actin andinyosin are present generally in eukaryotic cells, the quantitative contribution by skeletal inuscle 34nethylhistidine to the total urinary output of the anino acid is hnportant to know if it is to be used as an index ofinuscle protein degradation. The assesanent of the protein-bound 3-methylhistidine content of tissues and 48 organs of rats (Haverberg, 1975; Nishizawa et al., 1977), and in cattle (Nishizawa et al., 1979; Harris and Milne, 1981) has shown that 93 to 84 percent of the protein-bound 3-methylhistidine pool exist in skeletal muscle. These researchers all showed the mixed proteins, in all of the organs examined, contained detectable levels of protein- bound 3—MeHis. However, the total anount in these tissues is quite small compared with that of skeletal muscle mass. Much of the skepticism surrounding the use of 3- methylhistidine as an index for muscle protein degradation involves the unknown contribution of the tissues and organs to the urinary-excreted pool. The contribution of each tissue source to 3-MeHis in urine depends on its turnover rate as well as its size. Millward et al. (1980) indicates that non-muscle sources of 3-methylhistidine may account for a considerable proportion of urinary excretion of the anino acid. They looked at rats in the steady state and then made the assunption that the methylation rate (synthesis) should be equal to the rate of release of 3- methylhistidine (degradation). Millward et al. (1980) used two different experimental approaches to evaluate the validity of the use of 3-MeHis as an index for skeletal- muscle degradation. In the first experiment, synthesis of the protein-bound 3-methylhistidine from S- adenosylmethionine was measured in skin at 2.6196 day-1 1 ,in muscle at 1.08% day- and in the gastro-intestinal tract at 49 9.57% day-l, assuning the breakdown rates would be identical. In the second experiment, [M C-Cl-13] methionine was injected into rats and the radioactivity of 3-MeHis in urine was determined. They then analyzed the dilution curve, identifying three exponentials and equating than to muscle, skin and gastro-intestinal tract. By calculating the rate constants, the contribution of each tissue to urinary excretion was then determined, with muscle contributing 24.9% skin 6.8%, and gastro intestine 9.8% of the total excretion. Harris (1981) however, points out errors and inconsistencies in the data published by Millward et al. (1980). First, the pool size of 3-methylhistidine in the gastro-intestinal tract and its contribution to the total amount excreted were overestimated by a factor of 3. This would change the contribution from 9.8% to 3.1% of the total daily excretion. Second, the fractional synthesis rate of 1.08% day.1 measured in the muscle of 250 gran rats was 27% that measured in mixed muscle protein of the sane animals. In contrast, Millward and colleagues reported elsewhere (Bates et al., 1980) that actin and mixed muscle protein had fractional synthesis rates that were almost identical when measured in 100-150 gran rats in the sane way as employed by Millward et al. (1980). No explanation of this large relative difference was offered by Millward 50 et al. (1980), nor was any reference of Bates et al. (1980) quoted. Harris claims that the results are anbiguous and that present evidence supports the view that most of the 3- methylhistidine in urine originates in skeletal muscle tissue and as a result, remains a suitable index of muscle protein breakdown in vivo. Nishizawa et al. (1977) reported from studies of the comparative turnover of 3-MeHis-containing proteins in intestine, skin, and muscle, that intestine and skin may contribute about 17% of the total urinary 3-MeHis output. The accuracy, however, of this estimate is uncertain because the labelling technique used may be confounded by the reutilization of labelled methionine, which serves as the label donor for formation of labelled 3-methylhistidine (Young and Munro, 1978). Bates et al. (1979) presented data which suggest that skin and intestine are rapidly turning over pools of 3- methylhistidine and could make up substantial contribution to 3-methylhistidine excreted in urine. Again, using similar experimental techniques to Millward et al. (1980), they state that skeletal muscle may contribute as little as 25% of the total 3-methylhistidine excreted. Harris et al. (1977) however, measured the fractional breakdown rate of mixed muscle proteins and calculated that 90% of 3- methylhistidine in urine originated in muscle, assuning actin and myosin have similar rates of turnover. This 51 contribution of lnuscle to 34nethylhistidine in urine becanes approximately 80% if correction is made for the rate of actin breakdown being 88%iof nflxed nmscle protein (Lobley and Livie, 1979) and assuning thatlnost of the 3- tnethylhistidine franinuscle originates in actin (Haverberg et al., 1974). Sane studies have been conducted utilizing 3- inethylhistidine as an index for skeletallnuscle breakdown. Young et al., (1973) first discussed the potential use of 34nethylhistidine excretion as an index of progressive reduction inrnuscle protein catabolisn1during starvation in obese human patients. The excretion decreased progressively with starvation. These findings suggested that the reduced output of urinary 34nethylhistidine coincided with decrease urinary N output due to an adaptation and decrease in catabolisnioflnuscle proteins as starvation progressed. Haverberg et al. (1975) using rats, showed a narked and progressive decrease in 34nethylhistidine excretion in the protein-depleted group. The group restricted in both dietary protein and energy, showed an initial anall increase in daily 3-MeHis output, but then a decrease in excretion. These results were confinned by Funabiki et al. (1976) and Nishizawa et al. (1978), in subsequent studies. Ogata et al. (1978) and Nishizawa et al. (1978) both showed an increase ir1 34nethylhistidine excretion initially in 52 starved rats, indicating an increase in degradation of muscle. Ogata et al. (1978) did not see a decrease in excretion, however rats were starved for 72 hours then fed for 24 hours. Nishizawa et al. (1978) did see a decrease in excretion of 3-methylhistidine after 4 days of starvation. Onstedt et al. (1978) used 3-methylhistidine excretion as an index for muscle degradation in evaluating protein quality. They found that when higher quality protein was fed to rats depending on the protein uptake, an increase in urinary output of 3-methylhistidine occurred. Nishizawa et al. (1979) attempted to evaluate and determine the fractional catabolic rate of myofibrillar proteins of skeletal muscle in cattle during growth, using urinary 3-methylhistidine excretion. He concluded that the catabolic rate of muscle protein was approximately 1.22%/day. There have been several studies utilizing 3-MeHis excretion clinically to evaluate burn victims (Bilmazes et al., 1978) and Duchenne muscular dystrophy patients (Ballard et al., 1979). These studies indicate that with severe burns the excretion of 3-methylhistidine is increased (Bilmazes et al., 1978) and decreased in patients suffering from musclar dystrophy (Ballard et al., 1979). In another report, children suffering fran severe protein-energy malnutrition and children undernourished (Nagabhushan et al., 1978) showed decreased protein 53 degradation with 34nethylhistidine excretion decreased during nalnutrition and undernutrition and increased considerably after treaflnent. 54 OBJECTIVES To detennine if an energy level effect on canposition of gain does occur in cattle. To detennine the differences in canposition of gain in cattle varying in frane size. To detennine the validity in using 34nethylhistidine as an index to naasurelnuscle protein degradation in cattle. To detennine if a frane size effect for degradation of inuscle protein does occur in cattle. MATERIALS AND METHOD PROTEIN ACCRETIG‘I AND COMPOSITIGNI OF GAIN STUDIES TRAIL 1 - ENERGY EFFECT Experimental Animals A feedlot trail was conducted from December 11, 1978 to October 11, 1979 utilizing a total of 31 7/8 blood to full blood Limousin steers. They were quite uniform in their type, frane and condition. There was a two month spread in birth dates ranging from March 8, 1978 to May 14, 1978. Experimental Design and Rations The experimental design is outlined in table 1. It consisted of a growing phase and a finishing phase with the switch occurring when the cattle weighed approximately 340 kg. The average initial weight was approximately 254 kg. All cattle were terminated at a constant weight of 522 kg. All cattle were allotted to one of four treatments with 7 head allotted to each treatment. Three steers initially and four steers at the midterm switching point were slaughtered to determine body composition. Therefore, 24 steers were on trial for the entire experiment. 55 56 Table 1. Experimental Design For Studying the Energy Effect on Composition of Gain (Trial 1) Treatments 1 2 3 4 Growing Phasea (250 kg-340 kg) Energy Levelb HIGH HIGH LOW Low Days on Feed 70 70 102 103 Finishing Phasea (34o kg-522 kg) Energy Levelb HIGH Low Low HIGH Days on Feed 160 211 198 139 aDiet during growing phase balanced at 13% C.P. Diet during finishing phase balanced at 11% C.P. 80% HMC (DM Basis). A11 corn silage. bHigh energy diet Low energy diet S7 Rations are shown on table 2 and are divided into high energy and low energy diets by phase. Cattle assigned to the high energy ration were initially offered an all corn silage ration (dryinatter basis). The corn portion of the diet was increased to 35% highinoisture corn the first week then increased to 60% the second week. By the third week steers were on the full-feed 20% silagecorn ration. This procedure was used to adjust steers to the high grain ration both initially and at theinidtenn switching point. Trial 1 utilized four treaflnents to evaluate the energy effect on canposition of gain. Treaflnent l steers were fed the high grain diet during both the growing and finishing phase (HH). Treaflnent 2 steers were fed the high grain diet during the growing phase and the high silage diet during the finishing phase (HL). Treannent 3 steers received the high silage diet during both the growing and finishing phase (LL) while treaflnent 4 received the high silage diet during the growing phase and the high grain diet during the finishing phase (LH). Managgnent Procedures Within 24 hours of arrival to the MSU Beef Cattle Research Center, all steers were given identification tags, and vaccinated for pasteurella, 1BR, BVD, AND PH . All 3 cattle were injected with 21nillion I.U. of vitanin A. 58 Table 2. Rations Fed to Limousin Steers in Feedlot Study (Trial 1) andng Ifindamug' fifiji Ifigh Hfifii Ifigh Int-ref. Stkma (Rabi Efilage Gfifin Tami no. % 111 % DM %114 % DM Corn, aerial pt, w-ears, w-husks, ensiled, well-cared 3-08-153 87.00 20.00 92.00 20.00 mx. 50% mn. 30% ‘ dry matter Corn, dent, yellow 4-02-931 72.90 78.00 grain, gr 2 US Soybean, seeds, meal 5-04-604 12.14 5.85 7.08 1.38 solv-extd Limestone, grnd 6-02-632 0.96 0.33 Phosphate, deflouri- 6-01-780 0.57 0.63 nated, grnd Trace Mineral Salt 0.25 0.25 0.25 0.25 Vitamin Aa 0.02 0.02 0.02 0.02 Vitamin Db 0.02 0.02 0.02 0.02 Percent of ration dry matter: Crude Proteinc 13.00 13.00 11.00 11.00 Calciumc 0.46 0.46 0.46 0.46 phosphorousc 0.34 0.34 0.34 0.36 a30,000 IU vitamin A per gram. b 3,000 IU vitamin D per gram. cCalculated from average nutrient composition (NRC, 1976). 59 Rations were nflxed innadiately prior to feeding in a horizontal batch mixer. The canplete ration was then transported by conveyor belt to the appropriate pen feedbunk. Cattle were fed 3g libitun once daily in sufficient anounts so that bunks were nearly cleaned up at feeding time. Daily feed records were maintained and periodically, the unconsuned feed was renoved, weighed and the anount recorded. All cattle were group-fed and housed in concrete lots. which were partially covered, and bedded with straw. Approximately one-half of the floor space of each pen was covered by a roof. Autanatic waterers supplied the cattle with adequate anounts of water. Slaughter Procedures and Carcass Evaluation Initially three cattle were selected to be representative of those cattle placed on feed in the trial and body canposition was detennined using the 9-10-llth rib section technique. Anhnals were slaughtered at a packing plant location 25 miles from the Beef Cattle Research Center. Intennediate slaughter calves were also selected to represent the average calf in the treannent pen. One steer per treannent, a total of four, was slaughtered and body canposition was detennined using the 9-10-11 rib section analysis technique. Animals were slaughtered at the MSU Meats Laboratory. 60 Cattle were all slaughtered at the termination of the trial at the MSU Meats Lab. Body composition was determined on the carcass using the specific gravity technique and the 9-10-11 rib section analysis. Hot carcass weights were obtained along with carcass data after the carcasses had been chilled a miniman of 24 hours. Body Composition Determination Body canposition of the experimental animals was determined by either specific gravity, 9-10-11 rib section analysis or deuteriun oxide dilution and in sane cases all three methods were used as a canparison of techniques. Initial, midterm and final kill steers all had body canposition determined by the 9-10-11 rib section and D O 2 dilution techniques. In addition, all final kill steers had body canposition determined by the specific gravity technique. The 24 steers that were on test the entire trial were infused with D20 on six occasions: initially, finally, midterm switching point, half way through the growing phase and twice during the finishing phase. The object of the six body canposition determinations using D O 2 was to monitor canposition of growth at 45-70 kg intervals. For all steers slaughtered, 9-10-11 rib analysis and D20 dilution were performed to canpare techniques in estimating canposition. The specific gravity technique was performed on final kill steers and canpared with both 9-10- 11 rib section and deuteriun oxide dilution techniques. 61 Correlations between the three body canposition techniques were then calculated. Specific Gravity The application of carcass density in detennining body canposition is the prhnary factor in the specific gravity method (Garrett and Hianan, 1969). Carcass weights are obtained on the chilled carcass in the air and under water. A galvanized steel tank, 112 an in dianeter and 183 an in height, was fitted with a triple-bean pan Toledo balance. The tank ‘was filled to near capacity' with ‘water, and crushed ice was added to naintain the tenperature of the ‘water at 10°C or lower. The front and rear quarter of one side of each carcass was suspended fran the balance and hnnersed underwater and the weight recorded. It is necessary to ranove any air pockets in the carcass before recording the weight. Carcass and water tanperatures were obtained periodically and recorded for later calculations of correction factors. The following equations were developed by Garrett and Himnan (1969) to esthnate carcass canposition using the density of the carcass: % carcass fat = 587.86 - 530.45 X SG %icarcass protein = (20.0 X SG - 18.57) (6.25) SG = CW in air (CW in air - CW in H20) (Correction for H20 & Care-tanp) 62 9-10-11 Rib Section The esthnation of body canposition by analysis of the 9-10-11 rib cut fran one side of each carcass used in trial 1, was developed and outlined by Hankins and Howe (1946). Rib sections were ranoved fran the carcasses and further processed at the MSU Meats Lab. Ribs were subsequently separated into bone and soft tissue. The soft tissue portion was ground through a Hobartlneat grinder (0.47 on screen) five tunes and thoroughlylnixed and a subsanple (1 kg) was frozen for subsequent analyses. Rib tissue was analyzed for nmdsture by drying approxhnately a 6 to 7 g sanple at 100°C for 24 hours. Ether extract was detennined on dried sanples with the Goldfisch procedure. Total N‘was determined on a l g wet sanple using a techicon Auto- Kjeldahl System. The following equations were used to esthnate carcass canposition fran the rib cut canposition: % carcass Protein = .66(rib protein (%)) + 5.98 % carcass Fat = .77 (rib fat (%)) + 2.82 Using the equations developed by Garrett and Hinnan (1969), anpty body canposition was calculated: B'npty Body Protein (%) = .7772(carcass protein (%)) + 4.456 Empty Body Fat (%) = .9246 (carcass fat (%)) - 0.647 63 Deuterium Oxide Dilution The idea of using isotopic dilution to determine the body canposition of live animals is not new. Byers (1979) developed a procedure that separates the empty body water fran gut water thus, improving the accuracy of the procedure. Deuterian oxide (99.8% D20) was used as a tracer for tracing body water in beef cattle. The D20 was made to physiological osmolarity by adding 9g NaCl/1000 ml. Ten grans of physiological D20 per 45 kg of body weight were infused to produce an initial blood concentration of 400- 600 ppm. A 30-45 cm piece of polyethylene surgical tubing (PE200), inside dianeter of 1.4 mn, was passed through a 12 gauge needle placed in the jugular vein in an animal that had its head restrained in a head gate. A one-way stainless steel stopcock was attached to a catheter in the vein. Following infusion of the D20, the stopcock and catheter was flushed with 50 ml of physiological saline to insure that all D20 was washed into the animal's circulation. All blood samples (12 cc each) collected were placed in heparinized test tubes to avoid clotting of blood. Following the collection of an initial sanple, preweighed syringes (50 or 60 cc) containing the desired amount of physiological D20, were infused in single dose as fast as possible. The catheter was flushed by withdrawing the 64 discarding 20-30 ml of blood inmediately prior to collecting the first sanple and 10 ml before the later sanples. Sanples were collected at time intervals sufficient to produce a dilution curve to calculate pool size. The time intervals were to or initial, prior to infusion to ascertain any background levels of D20. Then samples were collected at 20, 30, 40, 50 and 80 min., at 4-6 hours and 1,2, and 3 days after infusion. All animals were infused in the morning prior to feeding and weighed each day sanples were collected and averaged to attain the live weight used for calculations. Sanples were analyzed using methods by Byers (1979). Blood was transferred to 100 ml volanetric flasks, then attached to condensers (cold finger) which were partially submerged in super-cooled (-80°C) methanol. Vacuun (5 11m Hg or less) was then applied to the collection apparatus in order to lyophilize the blood sanple (3 hours recovery time). Water, collected fran the blood in the cold finger, was thawed and analyzed in an infrared spectrophotaneter. A Wilks Scientific Miran I Fixed Filter Infrared Analyzer was used to measure absorbance. A 4.0 micron filter was used to provide the wavelength that coincides with maximan absorbance of D20 and miniman absorbance for H20. Precision sealed calcian fluoride cells with 0.2 rnn spacers were used for all sanples. The 0.2 rnn pathlength reduces the anount of energy put through and electronic noise, and increases sensitivity of the equianent. 65 Since the absorptivity of D20 bands exhibit temperature dependency, a temperature controlled cell holder was used. Fluid was circulated through the cell holder from a temperature controlled bath to maintain a proper temperature (24.5OC). Aliquots of the HZO—DZO solution were injected into the Can cell of the I.R. analyzer which analyzed the concentration of D20 in the water to the nearest 1 ppm. After the water sanples were analyzed in the I.R. spectrophotaneter, the dilution curve was graphically analyzed. Using the two-pool open system kinetics fran Shipley and Clark (1972), pool size estimates were calculated. Figure 2 illustrates the model for the two- pool open system. The overall equations for the system are: t _ -k -k t SA,t .. SAo(l)e 1 + SA°(Z)e 2 Normalized General Equation-fraction of dose: - '8 t ’8 t qa/qao - Hle 1 + Hze 2 Where: qa = quantity of tracer in pool a Ciao: dose placed in pool a at zero time HI = (intercept 1) (Q3) H2 : (intercept 2) (Qa) Needed equations to solve for rate constants: Kaa H131 * H232 Kaa * Kbb = 81 * g2 Kaa Kbb ' Kab Kba z 3182 Flow Rate5° F 66 Kbb’ since pool a is the only outlet for pool b bb = overall turnover for pools A and B respectively Kaa ' Kba Kba Q ba a Fab = Faa = Kaa Qa Foa = Kab Qb 5°‘ Qb = Fab I Kab Pool Sizes: Pool A.= Qa = 1 / SAa0 Pool B = Qb = Fab / Kab 2-pool open systan exanple calculation: Live weight - 390 kg Dose - 99.50 grans Thne following infusion finin) 15 26 35 45 502 1496 3196 4596 67 Pool A Koa Pool B Kbo Figure 2. Model for a 2-pool open system. 68 By using a mathematical process called "curve peeling", the sani-log regression of D20 (pan) was plotted against thne following total equilibration to provide the intercept and slope of the line. Predicted D20 levels fran this regression for early sanples are subtracted fran actual concentrations at these thne and the sani-log regression of these differences 12 thne gives rise to the interceptl and slopel. Equations are shown in figure 3. Specific activity for late pool: 5At = 318.35e"°°°°677t Specific activity "peeled" for early pool: SAt = 163.08e'°°295“t Total function describing the SA of pool a: SAt = 168.08e-.02954t + 318.35e-.0000677t Dividing the intercepts by dose: 168.081ng/kg 500 mg 318.351ng/kg "E SA(to) values as fraction of dose infused. SAat = .001689e'°°295“‘ + .003199e‘°°°°°577t .001689 / kg water .003199 / kg water Solving for canparunent sizes,rate constants and flow rates: Q = 1 _ l _ a FA: — . 4888 - 204.58 kg where SAa0 = canbined intercepts of SAa curve, at to exponents = l 69 .001688e'-°2954t+.003197e'-°000677t .003197e-.0000677t \ . 001688e’ - 029541: TIME Figure 3. Kinetic equations for pool separation. 70 Nonnalized equation: HI = .001698(204.58) = 0.3455 H2 = .003199)204.58) = 0.6545 9a / qao = .3455e-.02954t + .6458-.0000677t K = H g + H g = (.3455) (.02954) + 33 l q 2 2 (.6545) (.0000677) = .0102515 Kbb = gl+g2-Kaa = .02954+.0000677-.0102515 = .0193562 K = K = .0193562 ab bb Kba=(Kaa)(Kbb)'(gl)(82 = (.0102515)(.0193562)-(.02954)(.0000677) K .0193562 bb K = Kaa-K .0102515 - .0101482 = .0001033 oa ba = Flow Rates: Fba = KbaQa = (.0101482)(204.69) = 2.077 kghnin Fab = Féa = KaaQa = (.0102515)(204.69) = 2.09838 kghnin oa - KoaQa = (.0001033)(204.69) = .02114 kghnin Since Fab = 1(8be 2.09838 kghnin - _ = 103.40 kg Qb ‘ Fab/Kab ‘ .0183562 Pool A = 204.58 kg Pool B = 108.41 kg Bnpty Body‘Water, kg = 1.038 (pool A) - 17.918 Castro-Intestinal weight, kg = .832(pool A)-17.918 Bnpty Body‘Weight, kg = Live weight - (Pool B(.83)- .31) 71 .3017(EB‘Water) Bnpty Body Protein, kg Bnpty Body Mineral, kg .0689(EB Water) Bnpty Body Fat, kg = Live weight - (G.I. weight + EB Hzo/.7296)' Statistical Analysis In feedlot trial 1, analysis of variance (Snedecor and Cochran, 1967) was used to exanine main effects and, interactions for all variables. Mutiple analysis of variance was then used when appropriate, and contrasts were designed for canparing selected treatment canbinations of primary interest. If P <.20, the level of statistical significance was reported. P< .05 was determined as being significant, while P<.01 was reported as highly significant. TRIAL 2 AND TRIAL 3 - FRAME SIZE EFFECT Experimental Animals Feeding trials were conducted fran April 22, 1980 to October 7, 1980 and fran November 5, 1980 to April 21, 1981 utilizing 20 cattle of two frane sizes. Steers representing the small mature franc-size were primarily Hereford, Angus, or Hereford X Angus cattle. Sinmental or Charolais crossbred steers were used as representatives for 72 large nature franc-size cattle. Cattle for trial 2 were purchased in March of 1980 to begin that experiment in April. Cattle for trial 3 were (USH and AHSC) steers fran the Lake City Breeding Project described by Harpster (1978). Average initial weights for trial 2 were 307 and 322 kg for anall frane and large fran respectively and the average initial weights were 206 and 288 kg for anall and large frane steers respectively for trial 3. The canbined average initial weights, for trial 2 and trial 3, were 260 kg for the small frane and 302 kg for the large frane cattle. Experimental Design and Rations The experhnental design and rations fed in trial 2 and 3 are presented in tables 3 and 4, respectively. The design of the two trials were the sane in both cases (Table 3). Large frane and small frane cattle were used to evaluate the effect of frane size on canposition of gain. Trial 2, consisted of 6 small and 6 large frane steers while, trial 3 utilized only 4 steers for each treannent. In both trial 2 and trial 3, cattle were fed a high grain diet (between 70 and 80% concentrate) with crude proteins of 13 and 14 percent of the rationdryinatter respectively. The roughage in the ration for trial 2 was pelletted corn cobtneal and for the ration in trial 3, chopped alfalfa hay (Table 4). 73 Table 3. Experimental Design for Studying the Frame Size Effect on Composition of Gain (Trial 2 and 3) Treatments 1 2 Growing Phasea SMALL LARGE Finishing Phase SMALL LARGE aYear 1 and Year 2 diets were isocaloric. Year 1 diet balanced at 13% C.P. Year 2 diet balanced at 14% C.P. 74 Table 4. Rations Fed to Steers Varying in Frame Size (Trials 2 and 3) Trial 1 Trial 2 Int. ref. Item no. % DM % DM Corn cob pellets 15.00 (#4, Andersons) mature Corn, dent, yellow, 4-02-931 69.46 78.76 grain, gr 2 US, cracked Soybean, seeds, meal 5-04-604 9.50 10.00 solv-extd. Sugarcane, molasses 4—04-696 5.00 Limestone, grnd 6-02-632 0.70 0.95 Trace Mineral Salt 0.30 0.25 Vitamin Aa 0.02 Vitamin Db 0.02 Percent of ration dry matter: Crude Proteina 13.00 14.00 Calciumb 0.40 0.46 Phosphorousc 0.36 0.34 a30,000 IU vitamin A per gram. b3,000 IU vitamin D per gram. cCalculated from average nutrient composition (NRC, 1976). 7S Managanent Procedures Calves used in these trials were either western bred or calves fran the Lake City Breeding project. All calves were processed within 12-24 hours of arrival at the MSU Beef Cattle Research Center. lncaning calves were vaccinated for pasteurella, 1BR, BVD, and P13 and were given intranuscular injections of vitanins A and D. After a 30 day adjusnnent period pour-on insecticide was applied to all calves to control grubs and lice. Vitanin A and D injections were given every 60 days to all calves on trial. Cattle were fed 3g libitun in individual feeders once daily. Ration ingredients fed in trial 2 were pranixed in batches of 2000 pounds at the feedlnill and bagged in paper bags. Mixing of the ration for trial 2 was done every two weeks, according to the cansunption of dry Hatter by the experhnental anhnals. Rations for trial 3 wereinixed daily prior to feeding in a horizontal batchinixer. Daily feed records were Inaintained and unconsuned feed was periodically ranoved, weighed and recorded. All cattle were individually weighed at the beginning of each experhnent and every' 28 days thereafter until tennination. Initial and final weights were detennined as an average of weights fran four successive days at the beginning and end of the trials. 76 All cattle were individually penned in 240 an square stalls in an environmentally controlled metabolism roan. Each steer had an individual feeder and access to an autanat ic waterer . Slaughter Procedures and Carcass Evaluation Trial 2, steers were slaughtered when they were estimated to grade high good to low choice. Steers in trial 3 were all slaughtered when it was estimated that 75% of the small frane steers would grade choice. Cattle in trial 2 were slaughtered at a small packer in Okemos, Michigan in two groups. Five of the small framed steers were slaughtered first then 4 weeks later, the remainder of the steers were slaughtered. Cattle in trial 3 were slaughtered at the MSU Meats Lab all within one week of each other. Carcass data were collected in a like manner regardless of the trial year and slaughter location. Canplete carcass quality and yield data were collected after carcasses had been chilled for a minimum of 24 hours. Body Canposition Determination Body composition was determined in the experimental animals using the deuteriun oxide isotope dilution technique previously discussed. Cattle in both trials were 77 infused with D20 to estimate canposition at the start of the trial, nudway through the trial and at the end of the trial prior to slaughter. Statistical Analysis To evaluate the statistical differences among frane sizes, a two way analysis of data was done including frane size and years. ‘The procedure of least squares was used because of the unequal nunbers of steers in the two years. A progran in the Stat 4 series was used on the Cyber 750 canputer at MSU. 78 MJSCLE PROTEIN DEGRADATION STUDIES 3-METHYLHISTIDINE AS AN INDEX OF MJSCLE BREAKDQVN Metabolism and Reutilization Study Experhnental Anhnals, Design and Collection Procedures Two Charolais crossbred heifers, weighing approximately 323 kg, were used to evaluate the fate of [17CJ-34nethylhistine in cattle during the winter of 1979. The heifers were housed in an environnentally controlled metabolism roan confined in individual 91 x 244 cm stalls designed to allow urine collection. Cattle used in this trial received a corn-hay ration during the collection period. The two heifers were each given 10.83pCi injections intravenously of [MCJ-B-methylhistidine. By placing an indwelling Foley catheter through the urethra and into the bladder, urine was quantitatively collected for 120 hours from the heifers. Urine volune was measured to the nearest ml and the quantity recorded. After agitating the urine collected during each time period, sub-sanples were taken. Remaining portion of urine collection was properly discarded through the MSU Radioactive Waste Disposal Service. 79 Scintillation Counting All radioactive determinations were made using a scintillation counter (Tracor), which had an autanatic quench calibration that was performed by the canbined external standard channels ratio method. Sanples were counted in ACS cocktail (aqueous counting scintillant, Amersham Corp.). [1“c1-3- For determination of the CPM of methylhistidine in the urine, sanples were placed in 15 ml of scintillation cocktail at quantities of 0.2 ml undiluted urine or 0.2 ml of urine diluted 1:4 with H20. A standard containing 0.05 ml of [14CJ-3-MeHis, used in the experiment, added to 15 mls of scintillation fluid was used to determine activity of label and a blank sample containing 0.2 ml water in 15 mls of cocktail was used to determine any background . 3-Methylhistidine Excretion Studies Experimental AnimalsJ Design, Ration and Collection Cattle used for this experiment were the sane steers utilized in trial 3 and described in a previous section. Of eight steers used, four steers were designated small franed and four steers as large franed, to evaluate first, the excretion of 3-Me1-lis as an index for muscle protein 8O breakdown and second, to determine if there was a frame effect on turnover rates in cattle. Cattle were fed a corn-hay ration balanced at 14% crude protein. This ration has been discussed in detail earlier. Urine collection was conducted by placing the steers in individual 91 X 244 cm stalls designed to allow collection of urine and feces. Collections were in 3 day periods every 35 days, for a total of five collections. Urine was collected in large plastic containers containing enough acid to acidify to pH 2-3; this required approximately 200 ml of 50%, H2504. The containers were emptied once daily, urine volunes were measured and recorded. Ten percent aliquots were secured, canposited for given steers during the collection period and stored at 5°C until the collection period was canpleted. After each 3 day collection period the canposited urine sanple was stored at -20°C until analysis. Urine Preparation and Analysis Urine sanples were centrifuged to remove sediments them deproteinized with equal volunns of 10% SSA (sulfosalicylic acid). After allowing the sanples to sit at least 60 minutes in ice, they were centrifuged at 1000X g for 15 minutes. Hydrolysis of urine samples using an equal volune of 12N l-Cl, was done by heating to 110°C for 20 81 hours in sealed tubes flushed with nitrogen gas for 30 seconds. Prior to hydrolysis, an internal standard, S-B- (4-Pyridylethyl)-L—cysteine (PEC) was added (1.01nl of nan PEC solution). After hydrolysis, the hydrolysate was then filtered through No. 2 Whatman filter paper. The filtered hydrolysate was then evaporated to dryness, redissolved in distilled water and re-evaporated to dryness twice. The dried hydrolysate was finally dissolved in 5 ml 0.2 M pyridine, and refiltered through Metricel 0.2 m membrane filter using alnilli-pore filtering systan. The pyridine dissolved sanple was applied to a colunn (1.5 x 7.5 an) containing a cation exchange resin, Dower 50WLX8 with 200-4001nesh designation. The colunn had 301nl water passed through to desalt the resin then was equilibrated with 40 ml of 0.2 M pyridine. The acid and neutral anino acids along with creatinine, were eluted with 100 ml of 1M pyridine and this portion was dried by evaporation. Histidine, lysine, lqnethylhistidine, Inethyllysine and inethylarginines ‘were eluted after the initial 100 m1 of 1M pyridine, with 150 ml of 1M pyridine solution. 82 The 3-MeHis fraction collected was evaported to dryness, then dissolved in distilled water and re- evaporated, twice. The sanple was then dissolved in finl of 0.01 N HCl and analyzed on an anino acid analyser (Dionex) using a Pico IV buffer systan‘with lithiun citrate buffers. A progran was nadified to elute all anino acids initially except the 3-MeHis and PEC fraction, which were eluted last. Creatinine Analysis Creatinine detenninations for the urine *were done using Folin's Method of the Jaffe reaction as described in Hawk's Physiological Chanistry (1965). RESULTS AND DISCUSSION Body Canposition Estimates Considerable research involving many diverse techniques has been done in attempts to develop reliable measurements of body canposition. In this study three. different techniques were utilized to estimate body canposition in cattle. Table 5 sarmarizes the results of canparisons between carcass specific gravity, deuteriun oxide dilution and 9-10-11 rib tissue separation techniques in an attempt to evaluate each method. The range in size of animals used for the canparisons was quite narrow (225 to 525 kg empty body weight) making the probability of getting high correlation coefficients less than if the range were wide. The formula used to describe the linear regression relationship between two methods being canpared was: y = mx + b. The y and x variables are supplied by the canparative data point of the methods being regressed. Variable m is the slope of the line and implies that for each change in y, a change in x occurs. The y-intercept is represented as b in the formula and is the point on the y- 83 84 Table 5. Relationships Between Carcass Specific Gravity, 9-10-11 Rib Separation and Deuterium Oxide Dilution Techniques for Estimating Body Composition Corr. y Variables Coef.(r) Intercept Slope SE Sp. Gr. vs. D20 Empty Body Weight .88 87.20 .81 3.27 Empty Body Water .60 18.53 .91 3.24 Empty Body Protein ;57 -.84 .98 1.18 Empty Body Fat .67 56.05 .54 3.40 % EB Protein .73 4.93 .70 .12 % EB Fat .53 12.99 .50 .71 D20 VS. Riba % EB Protein .72 4.24 .83 .12 % EB Fat .71 .78 .77 .60 Sp. Gr. vs. Riba % EB Protein .59 8.90 .53 .13 % EB Fat .48 11.05 .41 .73 aTwenty four animals were used to compare Specific Gravity to D20 and Rib Section techniques while, 31 animals were used to compare D20 to Rib Section techniques. 85 axis when the quantity is zero on the x-axis. Ideally, when canparing theinethods with each other, the slope would be 1 and the y-intercept 0. Any deviation fran ideal was subject to interpretation., Figures 4 through 9 graphically interpret the regression equations for various comparisons between specific gravity and D20 dilution. Empty body weight was most highly correlated (r=.88), but empty body protein weight had the highest slope 0n=.98). Percent anpty body fat had both the lowest correlation coefficient (r=.53) and the lowest slope (m=.50). Our data would indicate, by canparing y intercepts and slope, that specific gravity and D20 dilution are similar in their predictions of empty body water, which should confirm data reported by Byers (1979). An evaluation of the regression lines would indicate a trend for D20 dilution to estimate slightly higher empty body weights, along with higher quantities of empty body water and fat. Bnpty body protein estimates would appear to be quite similar for both methods. The correlation coefficients are not as high as those shown by Byers (1979), but when canparing weights in a similar range to those used in his experiment with ours, distribution of points follow about the sane pattern. 86 Figure 4. Empty Body Weight - Specific Gravity versus D20 Dilution. 87 .a muswflm omm nary pranwzmm >¢m¢ mm com P one out own q)- + 1 D 1 1 wzomeaazou onhHwoazou >oom an 60m (0!) 1H013M83 030 86 Figure 4. Empty Body Weight - Specific Gravity versus D20 Dilution. 87 .q madman omm flax. broawzmu >¢m¢ aw cam out one Own q)- d P + 11 11 11 ‘- mm 6cm wzowummmzou zouhflmomzou >oom (OM) 1H013M83 030 88 Figure 5. Empty Body Water - Specific Gravity versus D20 Dilution. 89 .m ouswam Don flax. ambazmm >¢ma am new new mum DON I D b q d d J 1 1 av L l ,OON mNN 6mm aha wzom H amazon. 20 H .P H momzoo >oom on (011) 83181193 020 90 Figure 6. Empty Body Protein — Specific Gravity versus D20 Dilution. 91 .o ouswam flaxv szhommmm >¢mo mm m3 ma. man map F P .1 d P 1‘1 ii L mm wzomumamzou zoahumomzou >oom 3 (OH) NISlOHdQB 020 92 Figure 7. Empty Body Fat - Specific Gravity versus D20 Dilution. 93 .m muswwm Lee. beam“ >¢mo am own emu b q F G q- ‘1' cm on q 5m 6m— wzomecmzoo zomhmwomzoo >oom #— IONI 16383 030 94 Figure 8. Percent Empty Body Protein - Specific Gravity versus D20 Dilution. 95 .m madman ON Abom. z~mwomm >am¢ mm 4 On. of v— #— ‘P P D 1 1 q E mzowumaazou zouhuwomzoo >oom (13d) NIBlOUd 030 96 Figure 9. Percent Empty Body Fat - Specific Gravity versus D20 Dilution. 97 .m ouswam Aboma ham >¢m¢ mm. ooo.un OOO.PN ODO.NN coo.b— ooo.u— u u v1 u +1 #1 " uoo.uu .r no no iboo.h— Au nu 60c.hu mzowamaazoo zoubumomzoo >oom oo.Nm (13d) 183 020 98 Figures 10 and 11 graph the 9-10-11 rib separation estimates against D20 dilution estimates. Correlation coefficients are high at .72 for % empty body protein and .71 for % empty body fat. The y intercepts and slopes indicate that rib separation estimates higher protein and slightly lower fat contents than the DZO dilution technique would predict. The canparison between 9-10-11 rib separation and specific gravity techniques shows a low correlation coefficient Figure 12 illustrates the low value for the slope in the regression equation canparing percent protein in the anpty body. The graph would also indicate that the specific gravity method estimates lower % protein values than rib separation. In evaluating the estimations of percent fat in the empty body by the two methods, Figure 13 very graphicaly interprests the regression equation. The wide scatter of points and the low correlation coefficient would indicate a very low relationship between the two techniques for predicting the % empty body fat in the sane animal. This conclusion is supported by similar findings in previous unpublished work by the author. Powell and Huffman (1968), using simple correlation coefficients between the various methods for predicting body canposition and chemically determined carcass canposition showed that the 9-10-11 rib section tissue separation was most accurate in predicting carcass fat 99 Figure 10. Percent Empty Body Protein - D20 Dilution versus Rib Separation. 100 .OH ansmaa Abomu szpomm owe ooo.- cochma oownca cached dawned coo .vu 11 d 4 ‘ J J Occ.¢u bov.m~ 69m.o« 6ou.m— dom.m~ wzowammmzou onhHmomzoo >oom oo.- (13d) NIBlOHd ABS 818 101 Figure 11. Percent Empty Body Fat - D20 Dilution versus Rib Separation. 102 .HH madman “pom. ham owe oomwuu om~.c~ ooo.mm omhnmw ooo.o~ F 1 . u A? D 1 q db l J oc.o~ 69m.NN émb.ou wzomeamzou onHHwomzoo >oom oc.mm (138) 183 839 818 103 Figure 12. Percent Empty Body Protein - Specific Gravity versus Rib Separation. .104 .NH answaa ON Hhuau ZHMFoma >¢mo aw mar 2. S. 3 my k a E I 1 d wzomeaazou onHHmomzou >Dom (1381 N13108d 839 818 105 Figure 13. Percent Empty Body Fat - Specific Gravity versus Rib Separation. 106 :9”: Han. >55 mm ooo.mm ome.m~ com.- emu.ca ooo.oa “ a a u 0 u n a "5981 e .2 Manama e . 90 a e 53. 2 0 Au 9 0 one o e e . . 0 com «a e e e O .r e o 52.8..“ 1r oqmm wzow H amazoo 20 H .— H womzou >oom [.1381 18:1 838 818 107 (r=.94) and carcass protein (r=-.96). They also indicated that specific gravity was not as good as the rib section Inethod in esthnating both fat (r=-.92) or protein (r=.89). Byers (1979) and Garrett and Hinnan (1969), however showed a very high correlation between specific gravity and carcass chemical analysis empty body water, which would also indicate accurate protein content predictions. we found that rib section and specific gravityinethods were lowly correlated while rib section and D20 dilution nathods werelnore highly correlated. This would indicate that if rib section is thelnost accurateinethod we used to predict body canposition then 020 dilution ranks second being alnore accurateinethod than specific gravity for the predictions of body canposition. It is evident that since the canparisons between the three methods used in this experhnent were not highly correlated, inixing of the techniques within a single trial could lead to errors in calculating change in body canposition. .A single technique should be used and while it may or may not accurately predict body canposition, the relative changes over tina could still be detennined. The usefulness of the different methods depend on several factors including: want or need for serial kill, discounting of danaged carcasses and equipnent and/or facilities to perfornieach technique properly. Each of the three methods have advantages over the other with the D O 2 108 dilution nathod being advantageous in studying growth of cattle when low nunbers are necessary and repeated observations are desired on the sane anhnal. Feeding Trial - Energy Variation In the past nmch controversy has arisen surrounding the area of nutritional change in cattle of all frane sizes and their effects on canposition of gain. We therefore designed a study to evaluate the effect of various energy levels on the canposition of gain in laterinaturing, large frane cattle. Feedlot Perfonnance Sunnaries of the performance fran each energy treatment are reported in Table 6. The performance for each feeding phase and overall are given. In each phase, those cattle fed the high grain ration had the highest rate of gain and the lowest feed requiranents per unit of gain. Although the means do not differ significantly between high-low and low-high treaflnents during the growing phase, the trend is evident for high energy rations to increase average daily gain over low energy rations. Cattle fed the high grain ration throughout the trial had a greater average daily gain for the entire trial (P< .05). Cattle fed a high grain ration only during the finishing phase 109 Table 6. Energy Effect on Feedlot Performance (Trial 1) Treatments H-H H-L L-L L-H SE Item Daily Gain, kg Growing 1.35a 1.14ab .89c .98bc .148 Finishing 1.11a .84b .94° 1.16: .016 Total 1.19a .91c .940 1.08 .016 Average Daily DM Intake, kg Growing 6.15 6.41 5.22 5.48 NA Finishing 6.87 5.76 6.66 7.19 NA Total 6.70 5.92 6.50 6.85 NA Feed Efficiency Growing 4.64 . 4.98 5.75 5.64 NA Finishing 6.19 6.86 7.09 6.20 NA Total 5.99 6.48 7.03 6.32 NA abcMeans within rows with different superscripts differ (P <.05). 110 showed higher average daily gains (P< .05) for the total trial than either treatments fed high silage during the finishing phase. These results are consistent with Jesse et al. (1976b), Crickenberger et al. (1978), Danner (1978), and Harpster (1978). The cattle in the high-low treaflnent had a negative response to reducing the energy content of their diets. Highlow cattle had the lowest average daily gains (.84 kg/day) during the finishing phase showing shnilar gains to the low-low treannent cattle for the total experhnent (.91 and .94 kg/day respectively). Body Cbmposition and Carcass Paraneters Bnpty body canpositions, detennined by the D20 dilution technique, of the cattle are shown in Table 7. Cattle for all treannents were infused at sinfilar weights and thus anpty body weights show little difference between treaflnents. Figure 14 illustrates the changes in anpty body water as anpty body weight increases. There is little difference in body water content between treaflnents. However, at a constant anpty body weight of 476 kg, treaflnents receiving high silage during the finishing phase hadinore anpty body water than the high-high treaflnent fed a high grain ration throughout the trial. 111 Table 7. Energy Effect on Empty Body Composition, By Perioda (Trial 1) Treatments H-H H-L L-L L-H SE Item Empty Body Weight, kg Initial 222.82 232.51 222.69 220.92 3.99 Period 1 270.16 269.96 256.32 262.41 4.67 Period 2 313.27 311.74 307.51 319.16 5.88 Period 3 388.58 369.48 364.70 370.11 7.14 Period 4 431.96 408.89 413.26 433.47 6.91 Period 5 476.55 458.21 473.89 476.87 6.96 Empty Body Water, kg Initial 136.66 145.95 137.74 140.09 2.40 Period 1 154.04 164.05 153.85 156.17 2.94 Period 2 181.40 181.98 185.68 186.65 3.24 Period 3 211.79 212.08 204.84 218.44 4.90 Period 4 233.16 232.63 228.82 239.14 3.17 Period 5 251.56 253.70 263.18 265.20 3.78 Empty Body Protein, kg Initial 41.23 44.03 41.56 42.26 .72 Period 1 46.47 49.49 46.42 47.12 .89 Period 2 54.73 54.90 56.02 56.31 .98 Period 3 63.90 63.99 61.80 65.90 1.20 Period 4 71.41 70.18 69.04 72.15 1.00 Period 5 75.90 76.54 79.40 78.50 1.25 Empty Body Fat, kg Initial 35.51 32.46 33.90 28.92 1.74 Period 1 59.03 45.12 45.45 48.36 2.90 Period 2 64.64 62.31 53.02 63.33 2.06 Period 3 98.30 78.80 83.94 70.71 4.59 Period 4 111.43 87.54 99.64 105.71 4.33 Period 5 131.76 110.49 113.17 120.24 4.42 aPeriod 2 is equal to midterm body composition and Period 5 is equal to final body composition. 112 Figure 14. Energy Effect on Empty Body Water Content. Hex. braHmz mm 8m mN.‘ 8m new SN 3 *II— I*I d u 4 q q ui c «EA .1! «A: .1?. .. “II .0. “Ewan 44m: .qH munmnm 1r PEN 1. I i. am mmeczmm zo hummmm >Ommzm (0H) 8318M 83 114 Figure 15 graphically presents the relationship between empty body protein and empty body weight. This relationship is identical to that of anpty body water with empty body weight since empty body protein is calculated from the water. Again, the differences in empty body protein content at given anpty body weight are snail but, at the tennination of the experhnent, the treaflnent receiving a high energy diet throughout the trial had lower protein content than those treatments receiving a low energy diet during the finishing phase. This difference in anpty body weight can be attributed in part to differences in days on feed. Cattle fed the high energy diet during the entire trial were on feed 70 days less than treaflnent group low-low and 51 days less than treaflnent group highlow. At their rates of protein gain, the treatments low-low and high-low could eventually have a greater amount of empty body protein at the terminal empty body weight and of course less fat. Figure 16 canpares energy treaflnent effects on quantity of enpty body fat at various anpty body weights. Cattle fed a high energy diet had more empty body fat present at any anpty body weight than those cattle fed a lower energy diet. This is consistent with data from Moulton et al. (1922) and Byers (1980). For the low-high treatment cattle, empty body fat increased dramatically after cattle were switched to the high energy diet. 115 Figure 15. Energy Effect on Empty Body Protein Content. 116 now Here brain: »oom >pazu DOW DOW cow P D u u q mzoo »oom zo Hummmm >Ommzm (0M) NIBlOHd 1008 AldNB 117 Figure 16. Energy Effect on Empty Body Fat Content. 118 vad IXT mad |+I «4.1 .mT "*LT. 1w: QHHHJ .bH madman Roxy pronz »oom >pmzw com Dow com h b 0 u d «. db d 1 6m do“ v“ mzoo >oom zo Hummmm >ommzu (OH) 103 A008 AidNH 119 Table 8 sumarizes the changes in the percent empty body protein and fat. For all treaflnents, percentage protein in the enpty body decreased with thne on feed while percentage fat in the enpty body increased iron the trial initiation until tennination, with the highhigh treaflnent having higher 96 empty body fat (27.6096) and lower 96 empty body protein (15.93%). This would be an expected result of high energy diets and is consistent with Guenther et al. (1965) and Byers and Parker (1979). Carcass characteristics are presented in ‘Table 9. Energy level had an effect on carcass paraneters with high- high and low-high treaflnents having higher dressing percentages, increased fat thickness, increased kidney pelvic heart fat and increasing yield grades. The high-high treaflnent had higher quality grades than other energy treatments. This would not be surprising, since higher energy intake has been known to increase fat in the carcass of cattle (Guenther et al., 1965), so one would therefore expect the factors influenced by fat quantity to be higher for treaflnents on a high energy diet. This data is consistent with and supported by other researchers at this station who detennined that at constant weights, high grain fed cattle will have nmre carcass fat and fat thickness with less of an effect on carcass quality (Crickenberger, 1977; Danner, 1978; Harpster, 1978; and Wbody, 1978). 120 Table 8. Energy Effect on Percentage of Empty Body Protein and Fat (Trial 1) Treatments H-H H-L L-L L-H SE Item Empty Body Protein, % Period 1 17.22 18.34 18.14 17.99 .212 Period 2 17.49 17.61 18.24 17.66 .095 Period 3 16.49 17.31 17.02 17.82 .222 Period 4 16.56 17.17 16.76 16.67 .169 Period 5 15.93 16.70 16.76 16.46 .193 Empty Body Fat, % Period 1 21.79 16.68 17.61 18.29 .963 Period 2 20.54 20.00 17.14 19.96 .454 Period 3 25.11 21.37 22.67 19.03 1.010 Period 4 25.98 21.37 23.86 24.27 .762 Period 5 27.60 24.06 23.79 25.39 .811 121 Table 9. Energy Effect on Carcass Characteristics (Trial 1) Treatments H-H H-L L-L L-H SE Item Dressing d d Percentage 66.03 64.70 62.99 66.13 .266 Adj. Fat d d Thickness, cm 1.08 .36 .59 .70 .042 R12: 9 area' 94.41 99.25 95.27 99.25 2.197 KPH Fat, % 3.17d 2.42 2.33 2.92d .141 Maturity Scorea 1.67d 2.17 2.33 1.50d .121 Marbling Scoreb 10.00 8.17 7.33 8.00 .171 Quality Gradec 9.33d 8.33 7.67 7.67 .307 Yield Grade 2.50d 1.28 1.68 2.07d .104 H°t farcass 334.76 316.54 326.14 330.67 5.380 Weight, kg :Maturity: A-=l; A=2; A+=3. C Marbling score: Quality grade: Good—=7; Good=9; Good+=9; Slight=8; Slight+=9; Small-=10. Choice-=10. dMeans within rows with different superscripts differ significantly (P<=.05). 122 Composition of Gain The effects of energy on daily empty body weight and tissue gains are sumnarized in Table ID by period. By evaluating the gains within phases by period, one can observe more subtle changes in rates of empty body gains. Figure 17 illustrates the changes occuring during the trial, in empty body weight gains. The empty body weights are graphed against days on feed thus, the slopes of the lines are the rates. The graph shows that treatments receiving the high energy diet during the growing phase gained more empty body weight per day than the other treatments. When treatment high-low is switched to a low energy diet, empty body gains decline and are the lowest of all treatments (.69 kg/day). After the switching point at which treatment low-high is changed from a low energy to a high energy diet, an increase in empty body weight gain occurs. This confirms the data of Byers (1980); that suggests that energy levels can alter daily empty body weight gains. Figures 18 and 19 reflect the changes in daily empty body protein and fat gains between periods. An interesting fact is that an energy effect on protein as well as fat accretion was seen. Energy levels in the diets affect not only fat gains, but also affect protein gains. Patterns are similar for the changes in both fat and protein accretion. Treatment high-high and high-low both have 123 Table 10. Energy Effect on Daily Empty Body Gains, by Period (Trial 1) Treatments H-H H-L L-L L-H SE Item Empty Body Weight Gains, kg/day Period 1 1.35 1.07 .62 .77 .061 Period 2 1.23 1.19 1.06 1.15 .070 Period 3 1.09 .81 .88 1.06 .040 Period 4 .89 .64 .78 1.26 .067 Period 5 1.06 .63 .85 1.06 .079 Empty Body Water Gains, g/day Period 1 496.46 516.88 298.35 297.82 2.211 Period 2 781.78 512.56 663.01 622.09 2.543 Period 3 440.44 423.92 294.86 662.26 1.362 Period 4 436.06 331.40 386.76 413.96 1.708 Period 5 438.10 270.13 483.96 635.72 2.275 Empty Body Protein Gains, g/day Period 1 149.79 155.94 90.01 89.85 .667 Period 2 235.86 154.64 200.03 187.68 .767 Period 3 132.88 127.90 88.90 199.81 .411 Period 4 153.34 99.99 116.68 124.89 .443 Period 5 106.76 81.49 146.01 155.00 .580 Empty Body Fat Gains, g/day Period 1 672.09 361.60 213.99 360.09 .655 Period 2 160.44 491.11 157.76 305.49 .607 Period 3 487.79 232.31 475.63 153.78 1.438 Period 4 267.91 140.96 253.24 699.84 1.533 Period 5 484.12 294.18 190.61 354.39 3.862 124 Figure 17. Energy Effect on Empty Body Weight Gain. 125 i: a: 3: E: ¢¢+>l< ozuom _J .NH muswfia com .,. N. 3 6cm 66¢ zaco pzmm zo pommmm romwzm om (0M) 1HOI3M 83 126 Figure 18. Energy Effect on Empty Body Protein Gain. 127 :3 m: 3: :1: ¢¢+* ozucw .mH manage com cow m>¢o can «r- db 4- zHco Foam 20 Hommmm >©mmzm (0H) NI31088 83 128 Figure 19. Energy Effect on Empty Body Fat Gain. 129 1.: m: 2: :1: MHW _l ozwaw .mH musmhm Dom m>¢o cow oo— H. I C. \. 3 a db uh- L .2: zHco Ham zo hommmm *Qmmzw *— (OHJ 103 83 130 higher protein and fat gains during the growing phase, than treaflnents fed the low energy diet. Beyond the find-term switching point a change occurs in the rates of tissue accretion for both high-low and low-high treatments. Treaflnent low-high has increased fat and protein accretion rates to equal and slightly exceed the rates shown by treaflnent high-high. This effect iSInirrored by the high- low treaflnent, showing decreased rates of fat and protein gain at or below rates for the group of cattle fed the high silage diet the entire trial. Table 11 shows the treatment effects on empty body gains, dividing the trial by phases. Cattle fed the high energy diet during either the growing or the finishing phase showed greater daily anpty body weight gains than low energy treaflnents during those phases. The treaflnents high-high and low-high had greater daily anpty body weight gains over the entire trial. Daily empty body water and empty body protein gains show patterns of proportional change since one is calculated frun the other. Figure 20 graphically surmarizes the changes in daily empty body protein gains between phases. The high energy treatnents have higher daily protein gain during both the growing and the finishing phases. Treatment high-low does not differ significantly fran low-low but a strong trend is shown in 131 Table 11. Energy Effect on Daily Empty Body Gains, by Phase (Trial 1) Treatments H-H H-L L-L L-H SE Item Empty Body Weight Gains, kg/day a a b b Growing 1.29 1.13b .83C .95a .040 Finishing 1.02: .69b .84b 1.13a .021 Total 1.10 .80 .84 1.06 .019 Empty Body Water Gains, g/day Growing 639.12a 514.72:b 469.95:c 452.08: .024 Finishing 438.48a 339.88b 391.44b 565.12a .018 Total 499.55a 383.43 418.14 517.01 .014 Empty Body Protein Gains, g/day Growing 192.82: 155.29gb 141.79:c 136.39: .006 Finishing 132.29 102.54b 118.10b 159.64 .005 Total 150.71a 115.68 126.15 149.75a .004 Empty Body Fat Gains, g/day b a Growing 416.26a 426.35: 187.53bc 334.11a .023 Finishing 419.49a 228.34b 303.79b 409.38 C .019 Total 418.51a 277.67 264.26 377.35a .016 abc differ (P‘<.05). Means within rows with different superscripts 132 Figure 20. Energy Effect on Daily Protein Gain. ENERGY EFFECT ON DAILY EMPTY BODY PROTEIN GAIN 133 Figure 20. 5 |||l||||||||l|lllllllllllllllll||||ll||l||||||||| :3 Illl||llllllllllll|||||||||||||||||||l|| r I||||IIll||l|||||||||||||||||||||| a |||l|||||||ll||||l||||||||||l||||ll||||||||||l||| 5 ||||||||||||||||||l||||||||||||||||||||||||||l||||| d llll||||||llllllllllllllllll||||||| a |||||||||||||||||||||||||||||||| t ||||||||||||||||||||||||||||||||||||||| a IIIII||||||||||||||||||||||||||||||||||||| :1 ‘I||||lllll|||||||||ll||||||||||l|||||||l|||| iJ|||||||||||||||||||||I|||||||||||||l||||||||l|||| % |||||||||||||||||||||||||||||||l|||||||||||||||||||||||||||||I I I 1 I O L0 100 O Ln H 200 PROTEIN DAILY 86‘? FINISHING TOTAL GROWING EXPERIMENTAL PHASE 134 favor of higher gains. The treaflnents that received a high energy diet during at least the finishing phase showed the highest rates of protein gain during the entire trial. A canpensatory effect in protein gain does occur for treat- Inent low-high (159.64 g/day) as canpared to treaflnent high- high (132.29 g/day). Although not significant, daily protein gain is higher than. that of treatment high—high during the finishing phase. Figure 21 illustrates the differences in daily fat gains between treatments during the two phases and the total experhnent. Energy levels have a marked effect on fat gains with treaflnents receiving the high energy diets gaininglnore fat per day than the low energy treaflnents in both phases. Treatment low-high was not significantly different than the two high energy treaflnents during the growing phase even though the rate was 80 g/day less. The sane situation occurred with the low-low and the low-high treatments during the finishing phase. ' Tables 12 and 13 show the effects of energy on enpty body tissue gains as a percent of anpty body weight gains. Although none were statistically different, cattle fed a high plane of nutrition during an entire feeding trial tended to show decreasing percentages of protein gain and increased percentages of fat gain. This would be in agree- Inent with data fran Byers (1979). Cattle fed on a high plane of nutrition during the growing phase then switched 135 Figure 21. Energy Effect on Daily Fat Gain. ENERGY EFFECT ON DAILY EMPTY BODY FAT GAIN 136 21. Figure 5 |||||||Ill||||||||||||||||||l||||||||Illllllllllllllllllll =1 ||||||||||l||||||||||||||||l|||||||||||||| rl||||lllllllllll||||l||||||||||||||||||||||| F |l|Illllllllllllll|l|||||||||llll|||||IllIllllllllllllllllllllllllll 5 l||||||||||||ll||l|||||||||||||||||||Illllllllllllllllll|||l|||||| d|||||||||||||||||||||||||||||||||||||l||||||||l|| a ||||||||ll||||||||||l||||||||||||||l||| E |||l|||l|||||||||l||||||||lllllllllI||Ill||Ill|||||l|lllll||||||||||| 5 llllllllllllllllllll|l||||||||||l||||||||ll||l||l|||ll a lllllllllllllllllllllllllllll F ||ll|||||||||||||||||||||||||||||lllllllllllllll||||||||||||||||l||||l E |||||I|||||||||||||||||||||||||||||l||||||||||||||||||||||||||||l|||| .l l J l O O O D :I' M 200 100 DAILY FINISHING TOTAL GROWING EXPERIMENTAL PHASE 137 Table 12. Energy Effect on Empty Body Tissue Gains as Percentages of Empty Body Weight Gains by Period (Trial 1) Treatments H-H H-L L-L L-H SE Item Empty Body Protein Gains as % of Empty Body Weight Gains Period 1 8.22 14.10 14.25 11.79 1.974 Period 2 17.20 12.88 18.61 14.90 .891 Period 3 11.91 15.26 10.40 18.76 1.079 Period 4 9.81 13.98 12.35 15.65 2.335 Period 5 8.47 13.77 16.46 13.95 2.285 Empty Body Fat Gains as % of Empty Body Weight Gains Period 1 62.64 35.93 35.26 46.42 8.969 Period 2 21.86 41.48 15.48 27.78 4.048 Period 3 45.91 30.69 52.73 14.78 4.903 Period 4 50.76 42.42 32.46 26.99 5.413 Period 5 56.77 44.02 25.20 36.62 10.224 138 Table 13. Energy Effect on Empty Body Tissue Gains as Percentages of Empty Body Weight Gains by Phase (Trial 1) Treatments H-H H-L L-L L-H SE Item Empty Body Protein Gains as % of Empty Body Weight Gains Growing 14.87 13.72 17.14 14.38 .435 Finishing 12.97 14.83 13.95 14.03 .460 Total 13.68 14.41 15.03 14.16 .334 Empty Body Fat Gains as % of Empty Body Weight Gains Growing 32.43 37.65 22.13 34.69 1.974 Finishing 41.07 32.63 36.60 36.24 2.091 Total 37.86 34.55 31.73 35.68 1.519 139 to a low energy ration showed a reverse effect, actually increasing in the percent of enpty body weight gain attributed to protein and decreasing fat contribution to empty body gains. Cattle in treatment low-low showed a pattern sinfllar to high-high. However, the percentage of anpty body gain as protein is higher and the fat percentage is lower. Treaflnent law-high follows a sinfilar pattern of decreasing the protein portion of the enpty body gain and increasing the fat. Fran the data presented in this section it is clear that energy has an effect on carcass traits, empty body weight gains and enpty body tissue gains. Our results do not agree entirely with the theory; that thelnaxhnun for protein and nmscle growth is genetically set, thus energy intake above needs for protein deposition is stored as fat. Thisnnay be the case in part if thernaxhnun rate of protein deposition is attained, but thelnaxhnun rate has not been detennined. According to‘Wbody (1978), Garrett (1979), and Byers (1980), the daily protein gain is Inaxhnized at approximately 1.0 kg daily empty body weight gain for English type breeds. Their daily protein gains were then Inaxhnized at 140 g/day. Figure 22 shows that in this trial with exotic cattle a rate of nearly 200 g/day protein gain was attained, per kg/day anpty body weight gain. Our data does not show a plateau orlnaxhnun daily protein gain that Byers (1980) has reported, however we did observe a 140 Figure 22. Energy Effect on Protein Content of Gain. 141 noxu szo ponmz mm *4aco one. u DON. u coo. v . com. com. 0 u u u u 0 ta 9 o 0 Au 9 . 0.“st 0 mm 1m 0 .1. 0 O O O 4.23 O O 0 g 0 9 16m" 9 1. 0 mu zHco mo mzou zo pummmm >ommzm (0) N100 NIEIOHd 83 11100 142 deceleration in the rate of protein gain when daily empty body weight gains were between 1.0 and 1.2 kg/day indicating a biological linflt for daily protein growth was being approached. Figure 23 illustrates the relationship of daily anpty body weight gains with daily anpty body fat gains. This graph shows that at the point where the rate of protein gain begins to decelerate, the rate of fat gain accelerates. Fran these two graphs one could project that for laterlnaturing breeds of cattle gaining approxhnately 1.1 kg/day anpty body weight, anhnalsrnaxhnize protein gain yet minimize the fat gain. After that point a greater percentage of anpty body weight gain will be fat. At anpty body gains as low as 0.6 kg/day, fat is being deposited along with protein. This would indicate that at any gain in anpty body 'weight, both protein and fat are being deposited. This would not support the theory of energy in excess of that required for protein deposition is used to deposit fat. High energy groups and the low energy groups deposited fat at high rates even during the growing phase with young cattle. And, at the same time both energy levels deposited over 100 g/day anpty body protein. Fran this it appears that energy is being partitioned between protein‘and fat synthesis. There does not seem to be a clear cut energy priority fronlprotein synthesis, rather at any energy intake level, a portion is used for protein gain and a portion for fat gain. 143 Figure 23. Energy Effect on Fat Content of Gain. 144 .aa massaa 00%.“ do cox. zaco HI¢Hm3 mu >4H¢o Dow.— P I no P 1 QC dunv ,ooo.u 1 L d com. 1 db cam. 9:25 1 éom .01 zHco Lo area 20 pommmm >ommzm or. (O) NIUO 189 83 11100 145 Our observation that canposition of gain can be altered by energy levels has not been a consistent observation as indicated in reviews by Nhrchello and Hale (1976), and Reid et al. (1968). Prior et al. (1977) did show changes in carcass canposition with changing energy levels. Their results indicated that the changes in canposition were due largely to a greater amount of fat being deposited. Our data shows that the changes in canposition were not due just to increased fat with higher energy diets but were also due to an increased protein deposition. Feeding Trial - Franc Size Variation A growing of interest in the cattle feeding industry has centered around large frmne cattle in the feedlot. The question to be answered is: Do large frame cattle have advantages over anall cattle in both protein and fat gain or do large frane cattle gain in very sinfllar patterns to that of small frame cattle. To test this contention, a trial was designed to evaluate the differences in performance and composition of gain for large and small franed cattle. 146 Animal Performance Surmaries of the performance differences between cattle of two frame sizes are shown in Table 14. The performance for both feeding phases and the overall performance are given. In the growing phase large frame cattle gained more body weight per day and, consuned more dry matter each day than small frame cattle. There was no difference in average daily gains between treatments during the finishing phase. However, small frame cattle consuned less dry matter daily than the large frame cattle. Large frame cattle gained more body weight per day over the total trial than small frame cattle, but the small frame cattle consuned less dry matter each day. Feed efficiency was not different between treatments during either feeding phase and over the total trial. Even though large frame cattle gained more weight per day than small frame cattle they also consumed more feed thus, their feed efficiency was no different fran small frame cattle. This is confirmed by Dinius et al. (1976), Prior et al. (1977), and Harpster (1978). Body Composition and Carcass Parameters The effects of frame size on empty body canposition are shown in Table 15. Cattle used for the large frame treatment were heavier than cattle used for the small frame treatment. This would be difficult to change since the 147 Table 14. Frame Size Effect on Feeding Performance (Trials 2 and 3) Treatments Small Large SE Item Daily Gain, kg Growing 1.17a 1.42b .052 Finishing .89 1.06 .042 Total .99a 1.20b .039 Average Daily DM Intake, kg Growing 6.71c 8.13d .238 Finishing 7.47c 9.67d .335 Total 7.15C 9.10d .260 Feed Efficiency Growing 5.71 5.86 .150 Finishing 8.85 9.11 .372 Total 7.36 7.59 .230 abMeans within rows with different superscripts differ (P‘<.05). CdMeans within rows with different superscripts differ (P <.Ol). 148 Table 15. Frame Size Effect on Empty Body Composition (Trials 2 and 3) Treatments Small Large SE Item Empty Body Weight, kg a Initial 235.77 267.853 7.307 Midterm 305.95c 356.03d 8.543 Final 371.56c 445.63 9.366 Empty Body Water, kg d Initial 120.93c 149.91d 4.387 Midterm 151.22C 193.236 4.870 Final 176.26c 234.88 5.627 Empty Body Protein, kg d Initial 36.49c 45.23d 1.323 Midterm 45.62c 58.30d 1.469 Final 53.18c 70.86 1.698 Empty Body Fat, kg Initial 69.79 62.35 4.239 Midterm 98.69 91.19 3.368 Final 129.98 123.71 3.127 Live Body Weight, kg b Initial 259.50: 301.36d 8.016 Midterm 340.31 399.05d 8.639 Final 413.70c 503.97 10.359 abMeans within rows with different superscripts differ (P< .05). cd differ (P< .01). Means within rows with different superscripts 149 larger cattle generally wean at heavier weights than anall frane cattle. Since the large frane cattle were heavier initially, their anpty body weights were also greater than small frame cattle. Thus at initial, midterm and final live weights and empty body weights, large frane cattle were significantly heavier. Figure 24 illustrates the frane effect on anpty body water. Large frame cattle had greater anounts of empty body water at all three infusion thnes and since anpty body protein is directly calculated fran empty body water we found that large frane cattle had greater anounts of anpty body protein than mnall frane cattle. These relationships are graphically shown in Figure 25. Not surprising, is the fact that there was no difference in absolute anounts of anpty body fat between treannents. Figure 26 shows that at any given anpty body 'weight, anall franed cattle are fatter. Thisrneans that large frane cattle were leaner at any given anpty body weight. This is consistent with work reviewed by Berg and Butterfield (1976) and by Prior et al. (1977). Carcass characteristics are presented in Table 16. There was a frane size effect on sane carcass paraneters. Snail frane cattle had increased fat thickness, less rib eye area and higher yield grades than large frane cattle. There was no difference in quality grades between 150 Figure 24. Frame Effect on Empty Body Water Content. 151 u a a m A? 1? mafia .eN enemas Dom Aaxg hzcmwz >oom >hmzm Dov com DON E d I db ma— .mva .Nba EN 1 .ému mzou >oom zo Hummmu wzmmm (0H1 8310M 1008 11803 152 Figure 25. Frame Effect on Empty Body Protein Content. 153 N.— :9: u m an. gamma... .mN ouswwm com Box. Fromm: >oom »pmzw ooe oom b b DON b d + 1| 1 41- azoo *oom zo hummmm mzcmm (0M) NI31083 1008 11803 154 Figure 26. Frame Effect on Empty Body Fat Content. onu Fromm: >oom >hmzw oom ooe eon eon .r .r T a .4 m N._ .m. a m .0. 1 age... . :2. .oN magmas .8 rd rm. f: I mzou >oom zo puummm uzcmm (OH) 103 1008 11803 156 Table 16. Frame Size Effect on Carcass Characteristics (Trials 2 and 3) Treatments Small Large SE Item Adj. Fat Thickness, cm 1.43c .72d .074 Ribeye Area, cm2 65.14a 84.88b 4.510 Quality Grade 8.50 7.80 .479 Yield Grade 3.26c 2.41d .132 Empty Body Protein, % b Initial 15.38a 16.76d .271 Midterm 14.80: 16.32d .175 Final 14.24 15.89 .177 Empty Body Fat, % b Initial 30.11a 23.86d 1.233 Midterm 32.75c 25.87b .795 Final 35.61a 30.39 1.234 abMeans within rows differ (P‘<.05). CdMeans within rows differ (P*<.01). with different superscripts with different superscripts 157 treaflnents and as would be expected fran body canposition data, the large frame cattle had a higher percentage of anpty body weight as anpty body protein and a lower percentage empty body fat than small frame cattle. Composition of Gain The effect of frame size on daily empty body weight and empty body tissue gains are smmarized in Table 17. Large frane cattle had greater empty body weight gains during the growing phase and over the total trial. Although not statistically significant, daily empty body weight gain tended to be greater for large frame cattle during the finishing phase. This would coincide with the similar differences in average daily gains during the sane periods. Daily empty body water gains and daily empty body proteins gains were greater for large frame cattle during both feeding phases and over the entire trial. There was however, no difference between daily empty body fat gain during the experimental trial. Table 18 presents data smmarizing the frame effect on empty tissue gains as percentages of the empty body weight gains. Cattle did not show a difference that was statistically significant for either anpty body protein or empty body fat gains as percentages of empty body weight gains during the growing phase. There was a tendency for large franed cattle to have a higher percentage of empty 158 Table 17. Frame Size Effect on Daily Empty Body Gains (Trials 2 and 3) Treatments Small Large SE Item Empty Body Weight Gains, kg/day Growing 1.00a 1.29b .060 Finishing .78 .90 .043 Total .87a 1.05b .041 Empty Body Water Gains, g/day Growing 434.68a 626.09b .039 Finishing 297.51a 435.53b .026 Total 353.90c 503.52d .023 Empty Body Protein Gains, g/day Growing 131.14a 188.89b .012 Finishing -89.76a 131.40b .007 Total 106.77c 151.91d .007 Empty Body Fat Gains, g/day Growing 404.42 429.15 .050 Finishing 368.62 301.85 .035 Total 390.96 362.26 .031 abMeans within rows with different superscripts differ (P < .05). CdMeans within rows with different superscripts differ (P‘<.Ol). 159 Table 18. Frame Size Effect on Empty Body Tissue Gains As Percentages of Empty Body Weight Gains (Trials 2 and 3) Treatments Small Large SE Item Empty Body Protein Gains as % of Empty Body Weight Gains Growing 13.18 14.82 .738 Finishing 11.32a 14.92b .787 Total 12.12a 14.87b .540 Empty Body Fat Gains as % as Empty Body Weight Gains Growing 40.34 32.69 3.374 Finishing 48.55a 32.20b 3.575 Total 45.06a 32.59b 2.463 abMeans within rows with different superscripts differ (P‘<.05). 160 body weight gain as protein gain and lower fat gain. During the finishing phase and over the total trial, large frame cattle had a greater portion of the empty body gain in the form of protein gain and a lower percentage as fat gain. Total dry matter consuned per kilogram of empty body weight was slightly higher in large type cattle. However, this slight increase in efficiency (Ferrell et al., 1978) by small cattle must be balanced against an 18% decrease in average daily gains observed in small frame cattle. Because large frame cattle were gaining empty body protein relative to empty body fat at a faster rate than small frame cattle, the energy requirements to maximize growth (protein deposition) in large frane cattle would be expected to be greater than for small frane cattle. Rattray et al. (1974) reported that protein synthesis requires 45.6 kcal of ME per gran of protein synthesized while fat synthesis requires only 10.2 kcal of ME per gran of fat synthesis which agrees with conclusions by Jesse et al. (1976b) that the fattening process is more efficient calorically than that of the growth process or protein deposition. A point still to remember is that fat has very little water associated with it, whereas muscle is approximately 8096 water. This would mean that the 161 efficiency of muscle deposition, on a wet basis, would be more efficient that fat as a wet tissue. Hence we can therefore interject that large frane cattle at similar empty body weight have more efficient tissue deposition compared to the small frame cattle. Bergen (1974) reached the sane conclusion in his work. A possible explanation of the difference in responses of empty body fattening to the high plane of nutrition by the two types of cattle would be that they were in different stages of physiological maturity or development. Assuning relative chemical composition is a valid estimate of physiological maturity, the large frane cattle had not reached the sane degree of physiological maturity as the small frane cattle. However, if degree of marbling or quality grades are used an in indicator of physiological maturity, then the two types were more similar. 162 3-Methylhistidine as an Index for Muscle Protein Breakdown in Cattle The use of 3-methylhistidine as an index of muscle protein breakdown has been used in rats (Haverburg et al., 1975; Nishizawa et al., 1977; Onstedt et al., 1978; Nishizawa et al., 1978; Ogata et al., 1978; Ward and Buttery, 1979; and Dunn et al., 1980) and in hunans (Haverberg, 1975T; Bilmazes et al., 1978; Ballard et al., 1979; and Ward and Cooksley, 1979) for several years. This method has much potential as a means of quantitating protein breakdown in both man and animals. Limited work has been done to determine if this method can be used to quantitate muscle protein breakdown in farm animals. In view of the value of a non-destructive measure of muscle protein degradation in cattle, several studies were conducted to attempt validation of the method for use in cattle. Reutilization of 3-thhylhistidine The average recoveries of injected ltic-radioactivity in urine fran two yearling heifers are shown in Table 19. Urine was collected for 120 hours after injection to determine the percentage of the radioactive dose being 163 Table 19. Urinary Excretion of Radioactivity in Beef Catfie Following Intravenous Administration of c-3-Methy1histidinea Time After Percent of Injection (Hours) CPM Dose Excreted 4 6,612,365 30.2 8 2,667,103 12.2 12 1,296,233 5.9 16 768,285 3.5 22 849,413 3.9 28 1,118,693 5.1 34 840,198 3.8 40 523,445 2.4 52 1,100,978 5.0 64 1,104,375 5.0 80 1,206,000 5.5 96 816,400 3.7 108 496,125 2.3 120 261,300 1.2 89.7 aTwo crossbred Charolais heifers were used for recovery experiment. 164 excreted in that time period. Figure 27 graphically 14 illustrates the clearance of C-radioactivity by the 1"‘c elimination (1.65 x 106 heifers. A very high rate of CPM/hour) occurs within the first 4 hours after injection. The rate rapidly declines to a point of less than 0.22 CPM/hour at 120 hours after injection. Figure 23 depicts the increase in the percentage recovered of the original dose over time, the most rapid'rate of excretion occurs within the first 4 hours. It was not surprising that a major portion of the total dose (30.2%) was excreted during that sane 4 hour time period. At 8 hours after injection nearly half (42.4%) of the total dose had been recovered in the urine. The rate of elimination dropped steadily following the 8 hour collection time until the final collection at 120 hours, where 89.7% of the original dose had been recovered. The total amount of 14 C-radioactivity recovered is very similar to the 80-90% recovery figures reported by Harris and Milne (1981) in cattle. The rapid recoveries of radioactivity in cattle urine suggest that the urinary excretion of 3-methylhistidine is quantitative and thus satisfactory for the use as an index of muscle protein breakdown in cattle. These values compare with recoveries of 100% of the dose in 3 days fran rats (Young et al., 1972), 95% in 2 days from adult hunans (Long et al., 1975), 165 Figure 27. Elimination of 14C 3-Methylhistidine. 166 rso.1+.- afififl .mN mudwfim wmzo: on. oom me on on d- d- an l l éoo.u ¢OQ.N wazmzm wed mo zoahczmzmaw oo.o, (NOIWWIN) HOOH 838 083 165 Figure 27. Elimination of 14C 3-Methy1histidine. 166 =1o.1+.- .33 w .NN enemas wu— maze: com me em on 4 II)- 1. :1. L l 669.“ boo.N wHImzm oefi mo zoahmzazmaw oo.m. (NOITWIH) 800H 833 083 Figure 28. 167 Recovery of 14C 3-Methy1histidine. 168 _ umoo .x..- azwmum .wN enemas mug 950: com mp. om. mu. L mm 6m .mb warm—rm Us; .10 *mm>oumm cu (1N3083d) 183/\0338 3800 169 and 90-97% in 7 days fran adult rabbits (Harris et al., 1977). In contrast, sheep (Harris and Milne, 1980a) and pigs (Harris and Milne, 1981) only slowly excreted labelled 3-methylhistidine. Excretion of 3-Methylhistidine in Cattle- Frane Size Effects A study was conducted with young cattle of two different frane sizes in order to explore the effect of frane size on 3-methylhistidine excretion. The study was also intended to determine the degradation rate and the synthesis rate of the two different frane size cattle. Table 20 surmarizes the effect of frame size on daily excretion of 3-methylhistidine, creatinine and total nitrogen. During periods 2, 3 and 4, large frane cattle excreted more 3-methylhistidine per day than small frane cattle. This would indicate that large frane cattle are breaking down more protein per day than small frane cattle. Total daily creatinine excretion followed the sane pattern as the excretion of 3-methylhistidine. Large frame cattle excreted more creatinine than small frane cattle during periods 2, 3, and 4, corresponding with increased muscle mass for large frane cattle. 170 Table 20. Urinary Excretion of 3-Methy1histidine, Creatinine and Total Nitrogen in Cattle Over Time Treatments Small Large SE Item No. of Animals 4 4 3-MeHis Excretion, mmoles/day Period 1 1.69 2.43 .386 period 2 1.80a 3.07b .228 Period 3 2.34a 2.91b .110 period 4 1.95c 2.78d .109 Creatinine Excretion mg/day period 1 6351.72 6732.51 1004.049 period 2 7016.77a 10512.59b 563.442 period 3 7999.24a 10928.02b 525.748 period 4 8705.33a 11982.11b 576.069 Total Nitrogen . Excretion, g/day Period 1 53.81 61.10 7.745 period 2 52.83 69.17 7.646 period 3 90.12 87.70 5.943 period 4 76.79 80.91 6.271 abMeans within rows with different superscripts differ (P‘<.05). CdMeans within rows with different superscripts differ (P <.Ol). 171 Total nitrogen excretion was not different between the two frame sizes of cattle. This could be interpreted that large frame cattle were retaining more nitrogen, since their intake was greater than for small frane cattle. However, Harpster (1978) reported no difference in nitrogen retention between large and small frane cattle. Figure 29 graphically shows the pattern of change in excretion exhibited by the two frane size groups. Urinary 3-methy1histidine excretion remained relatively steady for both treatments with the large frane cattle excreting in the range of 2.5 to 3.0 rrmoles per day while the small frame cattle excreted between 1.6 and 2.4 mnoles per day, consistent with figures reported by Nishizawa et al., (1979) and Harris and Milne (1981). Thus, from these results it can be concluded that the excretion of 3- methylhistidine did not differ with time but did differ between cattle of different frane size. Urinary creatinine excretion was measured throughout the study and the patterns of excretion are shown in Figure 30. There was a steady increase in creatinine excretion over time with both large and small frane cattle following a similar pattern. The differences between the two frane sizes in creatinine excretion were statistically significant, ranging fran 6.732 to 11.982 mg/day for large 172 Figure 29. Daily 3-Methy1histidine Excretion. 173 «.d _ m Am: 6.. azuau4 .eN enemas ON— m>¢o L coo.— 60m.— 166°.N 66m.N 66a.m zompmmuxw wmzmzm xauco om.m (83100”) 3N10IISIHW1H13N-8 031383X3 174 Figure 30. Daily Creatinine Excretion. 375 N L ..m IE! 10.. qzwmuJ .om ouswam can w>¢o or ee «r- {D 4!- db 'P 3 l .«u zoapmmuxm wzuzupcmxu »m¢zux: (ON) 3NINIIU383 031383X3 176 frame cattle and 6.351 and 8.705 mg/day for small frame cattle. The increase in creatinine excretion was expected since the muscle mass in the growing beef animal was increasing. Table 21 shows the urinary outputs, body weights and the daily 34nethylhistidine output per unit of body weight for the large and small frame cattle during the study. Urinary output for both frane size cattle were not different, generally, reflecting water consunption during collection periods. Body weights were different between frane treatments for all periods except period 4 which shows near significant differences. Daily output of 34nethylhistidine per unit of body was not different between treaflnents and did show shnilar patterns of change. Figure 31 diagrans the changes showing decline in 34nethylhistidine per unit of body weight. This could indicate that the nmscle being broken down represented as a percent of the total anpty bodylnass was declining with thne. Table 22 and Figure 32 show the change in urinary creatinine excretion per unit of body weight. There was a statistical difference due to frame size during period 2, but the differences during periods 3 and 4 ‘were not significant although creatinine excretion ranained somewhat higher than in small frame cattle. This would 177 Table 21. Relationship Between 3-Methy1histidine Excretion and Body Weight in Growing Cattle Treatments Small Large SE Item No. of Animals 4 4 Average Daily Urine Output, liters Period 1 4.488 8.232 .868 Period 2 5.231 6.000 .346 Period 3 5.608 6.331 .442 Period 4 5.089 4.981 .519 Average Body Weight, kg period 1 216.75a 298.50b 15.010 period 2 254.25a 338.50b 15.819 period 3 292.75a 377.00b 16.830 Period 4 332.00 416.00 17.951 Daily 3-MeHis Output/ Body Weight, mole/kg Period 1 7.238 8.125 1.208 Period 2 7.245 9.063 .704 Period 3 8.068 7.720 .158 Period 4 5.935 6.695 .227 abMeans within rows with different superscripts differ (P< .05). 178 Figure 31. 3-Methy1histidine Excretion Per Unit of Body Weight. 179 ~.. _ m um! 10.. Quad“; .Hm osswam w>¢o sea or I!- or q- 1(- 1. C. qu- Htonz >oom mo kHz: mum szwzm 'M'8 OH 838 SIHBNS 180 Table 22. Urinary Creatinine Excretion Per Unit of Body Weight in Cattle Treatments Small Large SE Item No. of Animals 4 4 Daily Creatinine Excretion Per Unit of Body Weight, mg/kg Period 1 19.55 17.08 3.422 period 2 27.23a 31.05b .697 Period 3 27.39 29.40 .721 Period 4 25.31 29.04 1.023 abMeans within rows with different superscripts differ (P < .05) . 181 Figure 32. Creatinine Excretion Per Unit of Body Weight. 182 u L _ m 10.. 0.. azuauJ .Nm gunman w>¢o oua so oe 1r- «- qu- n- 4L pramwz >oom kHz: mum mzuzupcwmo 'M'8 OH 833 3NINIIU383 183 coincide with the difference in body canposition between the large frane and the small frane cattle, indicating more lean mass per unit of body weight. The levels of. creatinine excreted per unit of body weight may decline slightly after period 1 coinciding with changes in the canposition of the body and decline in the muscle mass relative to the empty body weight. Of course, once the animal has matured and body composition changes less, the creatinine excretion will remain rather constant. The ratio of 3-methylhistidine to creatinine excretion is an indication of the rate of muscle degradation relative to muscle mass. Table 23 and Figure 33 show the changing of the ratios in growing cattle. There were no differences between treatment groups in excretion of 3-methylhistidine per unit of creatinine. There was however, a trend shown to decrease the excretion of3-methylhistidine per unit of of creatinine as the animals age increased. We can conclude from these ratios that degradation of muscle protein per unit of muscle mass for large frane cattle and small frane cattle does not differ. An estimate of myofibrillar protein degradation rates can be made from the output of 3-methylhistidine in cattle. An example calculation is shown in Table 24 using a steer weighing 300 kg with 50 kg of empty body protein. Berg and Butterfield (1976) report that approximately 55% of the empty body protein is associated with skeletal muscle. 184 Table 23. Urinary 3-Methylhistidine to Creatinine ratios in Growing Cattle Treatments Small Large SE Item No. of Animals 4 4 3-MeHis/Creatinine Ratio Period 1 .305 .290 .191 Period 2 .268 .289 .022 Period 3 .297 .267 .011 Period 4 .227 .235 .011 185 Figure 33. 3-MeHis to Creatinine Ratio. 13f N D a m LU: 10.. azUGMJ .mm enemas owu w>¢o om ov cm- ‘1' ‘1' J. cocoa. boomu. coon. onpcm mszHhmwmu OH murmzm comm. 3NINIIU383 01 SIH3N€ 187 Table 24. Example Calculation of Muscle Protein Turnover From Urinary 3-Methy1histidine Excretion in Cattle Average Body Weight = Empty Body Protein = Percent of Empty Body Protein Associated with Skeletal Musclea = Amount of Empty Body Protein Associated with Skeletal Muscle = Quantity of 3-MeHis in Mixed Skeletal Muscle Proteins = Total 3-MeHis in Mixed Skeletal Muscle Proteins = Average Daily 3-MeHis Excretion = Fraction of Total 3-MeHis Pool Excreted Per Day (Daily Excr./Tota1 Pool) = Half-life of Muscle Protein = %L%%% — 300 kg 50 kg 55 % 27.5 kg 590 mg/kg 16.23 g .096 moles 340.0 mg 2.01 m moles .021 tk=33 days aBerg and Butterfield, 1976. bNishizawa et al., 1979. 188 Nishizawa et al. (1979), detennined the concentration of 3- inethylhistidine inlnixed skeletallnuscle protein to be 590 mg/kg of protein. The total pool of bound 3- Inethylhistidine in skeletal nmscle protein was then calculated. Knowing the daily 34nethylhistidine excreted, one can calculate the fraction of total pool excreted per day or the fractional breakdown rate. The half-life of the protein can then be calculated to help define the turnover rate of the protein. Using the nwthod just explained to calculate nmscle protein turnover, canparisons between cattle of different frane size are shown in Table 25. The values showed near significance in favor of large frane cattle over small frame cattle when canparing amount of empty body protein and skeletal nmscle protein along with skeletallnuscle 3- methylhistidine pool. These values all showed gains in anount fran period 1 through period 4. The fraction of the total 34nethylhistidine skeletallnuscle pool excreted daily was not different between treannents or periods and when the half-lives of the proteins were calculated no differences between treannents were observed. The length of thne that the cattle were on feed and the age of the cattle could be a partial reason as to why we did not see large change in the half-lives of thelnuscle protein. The muscle did appear to begin to decrease in its rate of 189 Table 25. Muscle Protein Degradation in Cattle Using 3-Methy1histidine as an Index Treatments Small Large SE Item No. of Animals 4 4 Empty Body Protein, kg Period 1 29.37 40.80 2.605 Period 2 33.96 46.80 2.794 Period 3 38.43 52.64 3.016 Period 4 42.90 58.48 3.266 Skeletal Muscle Protein, kg Period 1 16.15 22.44 1.433 Period 2 18.68 25.74 1.536 Period 3 21.14 28.95 1.658 Period 4 23.59 32.16 1.796 3-MeHis Pool in Skeletal Muscle, moles Period 1 .0563 .0782 .005 Period 2 .0653 .0870 .005 Period 3 .0750 .0976 .006 Period 4 .0826 .1122 .006 Fraction of Total 3-MeHis Pool Excreted Daily, day’l Period 1 .0271 .0310 .004 Period 2 .0299 .0397 .004 Period 3 .0330 .0288 .000 Period 4 .0247 .0249 .000 Half-life of Muscle Protein, days Period 1 29.84 23.97 3.574 Period 2 24.68 21.64 2.132 Period 3 21.45 24.07 .894 Period 4 28.74 28.29 1.603 190 turnover toward the end of the study and perhaps the use of older cattle or a longer study would help to detennine if or when the beef anhnal begins to decline in rate ofinuscle protein turnover. Table 26 shows calculated accretion, degradation and synthesis rates of protein in cattle. The accretion rates were calculated by using the D20 dilution method to detennine body canposition then converted fran anpty body protein gains tounuscle gains using the conversion factor reported by Berg and Butterfield (1976). Degradation rates, in g/day, were calculated using the half-life values and the quantity of muscle protein in the animal. An assunption was made for this calculation, that the relationship betweenlnuscle half-life and nmscle quantity is relatively constant. Protein synthesis rates 'were calculated by sunning both accretion rates and degradation rates. Figure 34 graphically shows the difference between rates of protein degradation of large frane and anall frane cattle. There is a statistically significent difference in protein degradation during periods 2 through 4, with large frane cattle showing higher rates than anall frane cattle. A trend did seen to develop toward the end of the study for degradation rates to decline indicating that the anhnal is beginning to decelerate in its growth curve. Table 26. 191 Calculation of Muscle Protein Synthesis by Difference Using Rates of Accretion and Degradation Treatments Small Large . SE Item Rate of Max. Potential Muscle Protein Accretion, g/day period 1 72.13 103.89 ---— period 2 72.17 94.36 5.525 Period 3 70.21 91.77 5.364 period 4 69.66 91.73 5.369 Rate of Muscle Protein Degradation, g/day period 1 348.61a 501.37b 79.968 period 2 371.64a 634.59b 47.305 period 3 483.17a 602.23b 22.863 period 4 403.23c 575.42b 22.346 Rate of Muscle Protein Synthesis, g/day period 1 420.74 605.26 ---- period 2 443.81a 728.95b 54.129 period 3 553.38a 694.00b 30.898 period 4 472.89C 667.15d 26.792 abMeans within rows with different superscripts differ (P <.05). CdMeans within rows with different superscripts differ (P‘<.01). 192 Figure 34. Muscle Protein Degradation. 193 a A a m 10.. I01 azuauJ .em enemas ON“ w>¢o zoahcommowo szhomm magma: (0) 008030 1088 SON 11I00 194 Figure 35 depicts the rates of synthesis of the large frane and anal] frane cattle. The large frane cattle did have greater rates of nmscle protein synthesis than anall frane cattle fran period 2 on through the en of the study. A shnilar pattern to declining degradation rates are shown for synthesis rates also andinay play a role in decreased rates of protein accretion with age. Fractional degradation, synthesis and growth rates are shown in Table 27. The fractional rates between frame sizes did not differ significantly during the study. Calculation of the FBR.was detennined by dividing the daily anount of 34nethylhistidine excreted in the urine by the 3- Inethylhistidine pool in theinuscle. The FSR of thelnuscle protein pool was detennined according to fonnulas suggested by Funabiki et a1. (1976). FSR equaled the synthesis rate (S) divided by the amount of 3-methylhistidine in the inuscle pool. 5 was calculated fran the following fonnula: Kd(P - Poe-Kdt) e-Kdt 1 - P and Po are the sizes of the 3-methylhistidine pool in skeletal muscle at time t and to, respectively and Kd is the breakdown rate or FBR. Results show that FBR for both large and anal] frane cattle were approxhnately .03 day-1 which was higher than FBR reported by Harris and Milne (1981) of .015 day"1 ininature cattle and .012 day '1 shown 195 Figure 35. Muscle Protein Synthesis. 196 ~.d nmw an an nauau4 .mm gunman can m>¢o .OO¢ 60m lamb m~mw2~z>m szpomm magma: cm (0) H1N1S 1088 SON 13I00 197 Table 27. Fractional Breakdown, Synthesis and Growth Rates for Muscle Protein Treatments Small Large Item Fractional Breakdown Rate (FBR), day"l Period 1 .0271 .0310 Period 2 .0299 .0397 Period 3 .0330 .0288 Period 4 .0247 .0249 Fractional Synthisis Rate (FSR), day Period 2 .0321 .0410 Period 3 .0350 .0306 Period 4 .0264 .0272 Fractional Growt Rate (FGR), day Period 2 .0022 .0013 Period 3 .0020 .0018 Period 4 .0017 .0023 198 by Nishizawa et al., (197 ) in growing cattle. The FSR was approximately .032 day'l, similar to data reported by Lobley et al. (1980) where they showed FSR of around .02 '1 in growing cattle using 3H-tyrosine infusion. day When comparisons were made between accretion rates calculated fran the fractional growth rates and nmasured accretion rates on the sane animals, discrepancies occurred. The measured accretion rates were greater than the calculated rates. The differences in the two accretion rates are large enough to warrant sane discussion. Discrepancies between the two accretion ratesunay be due to thelnethods of calculation. The directtneasuranent Inay have sane experhnental errors however, the values are in line with data reported by Byers (1979) which would tend to validify those results. The calculated accretion rates using the FGR are based on measures of 3-methylhistidine excretion and the FBR. The calculation of the FBR was accanplished using several assunptions: (l) 55%»of anpty body protein is associated with skeletal nmscle; (2) the concentration of 3-methy1histidine in skeletal muscle is 590 ing/kg protein; and (3) nearly 100% of the 3- nwthylhistidine excreted is contributed by the nmscle 3- Inethylhistidine pool. If errors have occurred in these assunptions, the FBR would also be in error. 199 Because of the large quantity oflnuscle protein being dealt with in cattle onlyininute changes in the FGR would alter daily accretion dranaticalky. For exanple, if the calculated FGR, approxhnately .002 day4, were increased to .004 day'1 , the accretion rate would double fran 55 g/day to 110 g/day. Any anall error in the esthnation of FGR is inagnified when calculating accretion rates. The refinanent of the technique along with additional research in areas where facts rather than assunptions are needed, may produce a very useful research tool in the future to esthnate protein turnover in cattle. 200 CONCLUSIONS Steers on a high energy diet during the finishing phase had greater daily anpty body weight gains over the entire trial. Steers on a high energy diet during the finishing phase had greater daily empty body protein and fat gains over the entire trial. Steers on a high energy diet throughout the trial had a greater anount of anpty body fat upon tennination, than steers receiving, low' energy during finishing phase. Ainaxhnun rate of protein gain per day was not seen in these laterlnaturing cattle, even at daily anpty body weight gains of 1.2 kg/day. Large frane cattle gained at a faster rate and consunedlnore drylnatter per day, but showed no feed efficiency differences fran anall frane cattle. 10. ll. 12. 201 Large frane cattle gained more protein per day than small frame cattle with no difference in daily fat gain. At any given empty body weight during growth, large frame cattle contain more protein and less fat. 3-Methylhistidine is quantitatively excreted in cattle. Large frame cattle excreted a greater total anount of 3-methylhistidine and creatinine per day than small frame cattle. When canpared on a per unit of body weight basis, there was no difference in excretion of 3- methylhistidine or creatinine per day. A decrease in the 3-MeHis-creatinine ratio was shown with increasing age, with no frane differences indicated. FBR, FSR, AND FGR were not affected by frame size differences. APPENDIX Table A.1 202 RATION INGREDIENTS Ingredient International Reference No. Alfalfa Hay 1-00-071 Corn cob pellets --- Corn silage 3-08-153 Corn 4-02-931 Soybean meal 5-04-604 Ground limestone 6-02-632 Defluorinated phosphate 6-01-780 Sugarcane, molasses 4-04-696 Trace mineral salt Vitamin A premixa Vitamin D premixb a30,000 IU vitamin A per gram. 3,000 IU vitamin D per gram. 203 no._ on— ~o.. no. n._oc no._ n.ecn n.0mu «am c :4 awn on um._ and no._ no_ n.hen A..~ n.c~m o.oe~ «ea a :4 can on .m.— mn— oo._ no. _.mnn ~_._ _.n~n o.nn~ «SN c :4 can on so.. on. ~m.o nQ— o.eo~ oo.o _.nv¢ ~.o_~ New e :4 new on n~._ mn— c~.— nQ— _.enn no._ n.onn _.ce~ New c .za mum on n_.~ and o~.o nod m.~¢n sa.o ¢.aa¢ s.eo~ ~¢~ e =A emn on mm.o mm~ ~o.c Nod m.—NN mm.o ~.one n.ao~ con n a; can an ma.o ma— oo._ No_ o.oan 5a.: m.enn m.~m~ con n 44 saw mm mm.o mo. mm.o «on ~.ncn no.9 c.ann n.oq~ con m a; can an sm.o ma~ ao.~ «cg o.¢~n ea.o «.0cn n.no~ can m an new mm no.9 mm. ~m.o no“ ~.nen ~o.o _.-m 5.4mm com n 44 «on an mm.o ma~ o~.o ~c~ c.0Nn ma.o m.o~n _._¢N can n AA _mm on oo.o _.~ oo.o oh n.mon om.o o.~m¢ ~.on~ _m~ N a: can an om.o dun mo._ as «.mnn sm.o e.nom a.~o~ .mn w a: Nan an mm.o __~ n~._ on m.-n Aa.o o.mon n.cn~ ~m~ N a: mum mm ao.o —_N no._ as a.o~n no.o “.mdm ~.nn~ _m~ N A: new an -.o -~ on._ as m.e~n ~a.o m.m~n a..- _m~ N 4: _nm mm .a.o -~ co._ as a._nn ea.o n.ecn o.m- ~m~ N 4: san mm ~c._ con nc._ es ~.~an m_._ o.nnm ~.om~ emu _ a: mom on _~._ co. -._ oh o.o—n e~._ _.~m¢ m.nn~ cnu - a: can an n_._ oc- ~n.. om n.nnn o~._ o._~m n.ec~ can a a: men an e~.~ oo— me.— on ~.nmn cm._ ..~mn e.~m~ can u z: onn an o_._ oo~ oe.~ oh _.ccn N~._ n.oun n.mn~ emu _ :2 sun on mo.~ cc. o~._ on m.~0n o_._ n.om¢ n.o- can _ .== can an aev\wx.uo< when hav\w3.uo< camp ma.u3 cook .02 .2 .2 .2 .2 age: .2 9. RE 9.5: 9.. a: so use... use... .6: 6: mounuucum maugeucqm acqaouu acqaouo usuaouu deuce ”seam acquaeu can: lacuna iguana unoum com Au amauav .eue: oocaauouuom daavu>qaau ~.< canoe 204 .c— I oouozu 304 no I poem saw: an I too» omauo>< .oL . . Hanan me u + seesaw no . .tosuaaw "ououa auquoscb "ouooa mcuubummn o— N. m.N n.N ca.Na NoN.o o.wo N.mmn a NNm on N N N._ n.n om.no_ nno.c o.oo N.nnn a cum on N N m.N n.N co.eo mmo.o o.no c.n¢n a can on m a o.N o.n nn.a~ mon.o _.nc n.ceN a new on N N N._ n.n oo.oN_ n¢—._ n.no N.con c asn on o o o._ n.N mn.No_ mon.o N.co a.nNn e eNn on n n _._ c.~ no.3m .mn.o N.No n.cmN n can mm a o m.~ o.N _N.ma Nos.o —.eo _._cn n Nan mm N N o.N n.N co.oc— NoN.o m.nc o.Nnn n can mm m a N._ n.N o_.¢__ nno.o N.no e.Nnn n men an m o n.~ o.n co.oo_ ~mn.o m._o n.o_m a Non an N N n.N o.n n_.oN nno.° N.oo c.0cn n .mn mm o m m.~ c.n «N.Nm can.° _.¢c c.0oN N m_n an N N a.c n.~ oo.oo— cmN.o n.co _.N_n N Nnn an o o a.o n.~ nn.oa enN.c n.¢o «.mon N nNn an a a u.— o.N Nn.cm ~mn.o n.4o n.N—n N new an m a N.— 6.: nm.n~— _mn.o n.no e.Nnn N _nn no o— o— N._ n.N ~n.¢°_ ~mn.o _.mo c.9nn N NNn mm o— Nu o.N m.n oo.oo_ oNN.— N.No n.cnn _ men an a a o.N n.a Nn.oa n¢_.~ n.oo o.m_n _ can an ad ~_ a.N c.n «N.Nm omm.c N.¢o N.nNn — new on - N_ o.n c.n ca.Nm Nan._ °.no c.Non a onn an a o N.N m.n nn.na n¢_._ «.00 «.mnn u Nun an N N N._ n.N no.—o~ «no.9 n.oo n.Non — can an a as «as u as .o: eunuu cacao yum .aou< uam new annual uses .02 .oz azuuaaao emeaubuux puma» an: ahoawm .nv< lemon: ooaouuu yo: lacuna woman can .A_ Hmuusv quad maooueo Huauw>ueeu m.< wanes 205 sm.oN m..~_ eo.ee _N.Noa oo.NnN a «Na on NN.oa on.o_ oo.ns «5.85. oN.n_N e on on oN.nN oN.o ao.oe me.en_ .o.oNN e «an on No.NN no.8 NN.nN oe.o_a no.Nm_ a mom on an.NN oo.o No.Ne oN.oN_ oe.a_N e NNn on no._e on.s oo._e om.NN_ no.oNN a «Na on N_.oN .e.m no.on No.NN_ Ne.Nm_ N can an me.ne No.o_ oe.ne Ne.ms_ oc.NeN N Nam an nm.on _N. NN.oe e~.nN~ NN.eNN N can an oo.oN oN.o oo.Ne e_.Ne_ ee.oNN N new an eN.oN eo.o— oe.ma NN.ne_ Ne.oNN N Now an me.Nn on.o oo.oe mo.nn_ .N.NNN N saw an mo.on no.m N_.sn 2N.oN_ no.e_N N o_n an mo.oN eo.oa mo.Ne no.Nm_ NN.NeN N Nnn NN eo.oN Nn.o .o._e ao.nn_ oo.ooN N nNm NN oN.NN No.o_ mo.ee n_.oe_ an.NNN N New NN on.en no.oa No.ne No.ne_ so.NNN N .nn NN NN.eN no.__ on.oe on.oo~ om.omN N NNn NN so.Ne oN.o_ No.55 no.oea No.NeN _ men an Ne.NN N_.o oo.en oe.Nn_ oe.N_N _ can an n_.NN _N.m Nn.Ne so.oe. NN.oNN _ son an 2N.Ne oo.m nN.Ne .o.ne~ nn.NeN _ can an oo.nn No.2 oN.oN AN.oNa .o.N_N _ NNn eN mo.an Ne.m No.on eN.NN_ Ne.ee_ . can en .62 ms or as as as ass: .6: .oz .oos mm .assosa: nu .saooose nu .suon: an .uruao: as issues noose sum .1. stereo grandee .soeoaooeaoo moon Nos-n oNo assoqeaosn e.< «Home 206 NN.No as... NN.NN oN.NN_ .N.aoN e NNN oN NN.Ne NN.o. oo.Ne so.NN_ NN.NNN a eNN oN N_.Na oN.o_ NN.Ne No.NN_ N_.NoN a eNN oN N2.NN NN.N NN.Ne N_.Ne_ NN.NNN a Non oN .o.Ne N_.__ aN.Ne NN._oa NN.NoN e NNN oN NN.~N No.e Ne.Ne NN.es— .o.NeN a sNN oN No.NN NN.a .o.Ne NN.NN_ oN.NaN N can NN No._N o_.N_ eN.NN NN.oN_ NN.NNN N NNN NN oN.Ne NN.o_ oN.ee Ne.Ne_ No.NeN N can NN oN._N oN.__ NN.Ne NN.Noa NN.NNN N nan NN N_.eN NN.oa Ne.Ne NN.oN~ 5N.ooN N Non NN oN._e NN.N oo.Ne .N.ee_ oN.oeN N awn NN NN.Ne ee.o_ .N.Ne 2N.2N_ No.oNN N N_N NN o~.Ne N_.__ es.Ne NN.Ne_ .N.NoN N NNN NN __.eN No.o_ No.Ne oN.NNs NN.NNN N NNN NN No.oa No.o_ NN.Ne Ne.NN~ NN.NNN N Nan NN NN.NN _N.__ o_.NN NN.NN_ eN.NNN N .NN NN ~_.Na oN.N_ e~.eN ee.NNs No._oN N NNN NN NN.oo Ne.N_ No.5N No.aN_ Ns.NoN _ Non 5N NN._N .N.o_ No.oe NN.NN_ ne.ooN _ sen eN __.NN .e.__ No.oe No.Noa Na.NNN _ Non eN 5N.ao_ oN.N oN.oN NN.oN_ NN.NoN _ oNN 5N NN.Ne oe.oa Ne.oe NN.¢N_ NN.NNN . NNN 5N N5.NN .N.o_ o..ne No.Ne_ No.NeN . can 5N .62 we. we. ms 9— »: uses .0: . oz .oss em .aasosar em .saooose as .sooa: nu .osNao: an insane noose see .A_ assess _ tosses .soaoaaosaoo Noon Noses oNo assessaoae N.< oases 207 No.oN No.N_ No.NN No.NN_ Ne.NNN e NNN oN _o.NN NN.N_ oN.NN Ne.NN_ oN.N_N e oNN oN oN.NN NN.N_ oN.Nn oe.oN_ NN.eNN a ran oN NN.NN 5N.oa oe.Ne NN.NN_ NN.NNN a Non oN NN.No No.N_ No.NN No.NN_ Ne.eNN e NNN oN NN.NN NN.N_ oN.NN Na.NN_ N_.N_N 5 «Nn oN _N.NN ee.o_ _N.Ne .e.NN_ NN.NNN N can NN N2.NN No.e. No.5o NN.N2N _N.oNN N NNN NN NN.NN No.N_ NN.NN NN.eN_ oo.o_N N oNN NN NN.No NN.N~ NN.oN. NN.oN_ No.2NN N nan NN NN..N No.N_ eN.NN NN.NN_ NN.__N N Non NN NN.Ne NN.N_ No.NN oe.NN_ NN.NNN N .NN NN NN.oo NN... oN.Ne NN.so_ eN._NN N N_N NN oN.NN NN.N_ oN.oN oe.NN_ .N.~_N N NNN NN NN.NN No.N~ No.NN oe.eN_ Na.NNN N NNN NN .o.NN NN.N_ NN.NN oe.NN_ NN.NoN N Nan NN NN.NN ee.N_ 4N.NN No.NN_ No.oeN N NNN NN .o.2o NN.N2 No.NN NN.NN_ 5N.NNN N NNN NN oN.oN Ne.e_ o_.No eN.ooN Ne.NoN a con 5N NN.NN oN._a NN.Ne .e.eo_ oo.eNN . sen eN 5N.NN No.N_ NN.NN Ne.NN~ oe.NNN . Non 5N NN.eN no.N_ NN.NN N_.No_ NN.NeN _ oNN 5N NN.oN No.N_ oN.NN oN.NN_ o_.__N _ NNN eN No.Ne NN.__ os.oe eN.No_ oN.sNN . oNN 5N .62 as as as as or seen .62 .oz .uom em .Nasosaz NN .saoooss NN .soess NN .usuao: an insane sauna see .2. Noaneo N sesame .soaoaaoasoo Noon Nessa oNo Nostasassu o.< oases 208 Nm.NNN mN.wN Nw.oo e¢.oNN eo.eNe c wNw on wN.wc ow.eN ac.nc we.oNN oN.www c on on NN.ow wN.oN wn.NN nN.weN ww.amn e eww on mo.mw nn.NN No.ew No.aNN ca.w¢n a wow on No.40 wo.NN Nw.cN wN.NcN n¢.noc a wNw on wN.oo ow.¢N ac.we we.cNN ON.www o ch on NN.ac co.wN oN.Nw mw.amN NN.aon w cow wN wn.ooN NN.wN mm.oo m¢.NNN oN.oNe n an wm wo.Na NN.cN NN.No mN.coN Ne.omw w omw ww mo.oo om.eN oo.Nw me.NoN Ne.wmn w wcw wN ao.Nm wN.nN oN.ow Nw.ooN ww.won w New ww Na.mw ao.eN ON.No ow.eoN oN.aww n wa ww wN.oo so.NN NN.Nw mN.cNN No.mNn N me wn mo.mo oN.wN NN.oo 0N.oNN on.aow N Nww mm no.m¢ wo.wN aw.mw en.NNN Nw.oow N wNw mm ce.wm oo.nN mN.No NN.noN na.now N new mm co.~m mN.wN am.ow NN.NNN Nw.No¢ N Nww mm Ne.Nm oo.wN on.mw on.wNN oN.Nmn N NNw ww NN.woN om.wN ww.wN mN.qu mn.onq N now an mw.Nm mo.NN ww.ww wo.cmN wm.mcn N «cw an Nw.wm Nm.eN nN.wo Nm.wNN «N.wa N oow cw Nw.wwN ca.nN co.No an.NoN NN.NN¢ N enw on wN.NNN cw.cN mm.wc No.NNN ew.coc N NNw on mo.ww NN.qN cc.qo ow.wNN Nm.qu N oww an .62 w: mg as a: as Neal .02 .02 .22 am .1205: mm .538... 2 Juno: 2 .230: an .83... 53m :2 .2 22.: N .522 83022.38 :02 .3qu oNe 2:23.05 N.< oNsoN. 209 oN.NnN < >NNcn omeuo>< when NNNen uwauu>< who: Nusqm ms.u3 mN.u3 .02 use. .02 Nancy N ooNuom N voNuom N voNuom N voNuum N voNuom NeeNm NeNuNsN and» lacuna nooum .Nn can N NaNNav cue: quuBNONNUN NeapN>NocN ON.< oNaaa 212 Table A.ll Individual Carcass Data (Trial 2 and 3). Steer Treat- Year Adj. Ribeye Yield Quality3 No. ment No. Fat Area Grade Grade No. CM CM 198 1 l .65 10.5 3.6 9 50 1 1 .35 11.5 2.7 9 154 1 1 .50 9.8 2.8 7 122 . 1 1 .50 11.5 2.8 7 156 1 l .70 10.0 3.8 9 200 1 1 .55 10.6 3.1 6 63 2 l .50 12.1 3.1 10 60 2 1 .40 14.0 2.4 10 65 2 1 .20 11.4 2.3 7 64 2 l .25 12.3 2.8 7 61 2 l .25 13.8 2.0 7 62 2 l .35 12.2 2.4 10 196 1 2 .55 10.3 3.1 10 187 1 ‘ 2 .60 9.1 3.7 ' 10 160 l 2 .50 6.9 3.3 11 141 1 2 .75 10.8 3.7 7 139 2 2 .20 9.7 2.8 9 154 2 2 .40 10.0 3.3 7 109 2 2 .50 12.4 2.8 10 101 2 2 .30 12.0 2.2 9 aQuality score: Average good = 8; High good = 9; Low choice = 10. 213 NN.sN NN.N NN.oe NN.NNN oo.ooN N N NoN 5N.No NN.N oe.NN oN.NNN Ne.oNN N N NoN oN.NN oN.N NN.NN No.NNN NN.oNN N N eNN oo.oN eN.e No.oe oo.NNN No.oNN N N NNN NN.No oN.N oo.Ne NN.NNN Ne.NNN N N NeN NN.Ne No.N eN.oN oN.NN No.oNN N N ooN NN.No oN.o NN.oN N5.NN eo.oNN N N NNN NN.Ne eN.o NN.NN NN.NN NN.eoN N N oNN NN.Ne NN.NN oe.Ne eN.NoN No.eNN N N No NN.No os.oN NN.Ne NN.oNN NN.NNN N N No Ne.NN NN.NN NN.oo NN.NNN oN.oeN N N es oN.NN oN.NN NN.NN NN.eNN oN.NNN N N No NN.NN No.8 NN.Ne oe.NeN NN.oNN N N oo NN.oN NN.NN NN.NN oo.NNN NN.NNN N N No oN.No No.oN. NN.oe NN.eNN NN.NNN N N ooN NN.NN eN.oN NN.Ne No.eNN No.eNN N N oNN NN.NN NN.N wo.Ne oN.NeN oN.eNN N N NNN oN.NN NN.N No.NN NN.NNN eN.NNN N N eNN NN.NN oN.o NN.Ne No.NeN NN.oNN N N on eN.NN No.NN NN.Ne NN.NNN so.oNN N N NNN .oz 9.. 9N NNN we. 9N . oz usu- . oz .oes NN .NssosN: an .sNoeoeN NN .eooo: NN .NsNNo: an user lessee sooom .NN oer N Naneo NsNoNsN .soNoNooosoo Noon Noose NoseasNosN NN.< oNNoN 214 No.oN No.NN No.NN NN.NNN oN.wNN N N NoN NN.NoN No.NN oN.NN NN.eNN No.NoN N N NoN No.NNN NN.NN NN.NN NN.NNN NN.NeN N N ewN oN.NN oN.NN oo.NN eN.NNN NN.NNN N N NNN NN.NNN NN.NN so.NN wN.NNN .NN.owN N N NeN NN.NN NN.N me.NN NN.eN .oo.oNN N N ooN No.NN Ne.N No.Ne ow.NNN NN.oNN N N NNN No.oN No.N so.Ne Ne.NNN oN.NNN N N oNN NN.NN NN.eN NN.No eN.oNN NN.oNN N N No NN.NN N¢.NN oN.eN No.oNN NN.eNN N N No No.NN No.5N NN.No NN.oNN ee.eoN N N so NN.No No.eN eN.eo oo.NNN oo.NNN N N we NN.NN NN.NN NN.NN No.NNN eo.NNN N N co oN.NN NN.NN eN.No NN.NNN NN.NNN N N No eo.NN NN.NN NN.NN No.oNN NN.eNN N N ooN NN.eNN NN.NN Ne.ow NN.NoN No.NeN N N oNN oe.oo NN.NN eN.Ne NN.NoN NN.oNN N N NNN No.NN NN.oN NN.Ns NN.oNN Nw.NoN N N NNN NN.NN No.NN NN.oN No.NoN NN.NoN N N on NN.NNN Ne.NN so.Nw NN.NNN NN.oNN N N NNN .oz as as as as as .62 ass: .62 .eaN an .NseosN: am .sNoooss nu .Noes: Nu .osNNo: an user insane Noose .NN est N NstNN :NueeN: .soNoNnoaaou Noon Nessa NssoasNesN NN.< «Nags 215 No.NoN Ne.oN No.NN NN.NNN so.eNe N N NoN NN.NoN oN.oN NN.oN 5N.NNN 5N.NNe N N No— oe.NNN NN.eN om.eo eo.NNN oN.Noe N N NNN NN.NNN NN.eN NN.No NN.ooN oo.eNN N N NNN NN.eNN NN.eN aN.No eN.NoN oN.NNe N N NeN NN.NNN oN.o NN.oN NN.ooN NN.NNN N N ooN NN.NNN No.NN No.oN NN.NoN No.NNN N N NNN NN.NNN NN.NN so.NN Ne.NNN NN.NoN N N oNN oN.NNN NN.NN NN.eN eN.NeN eo.Noe N N No NN.NNN NN.e_ No.5o oN.eNN so.NNe N N No oN.NNN ee.NN NN.oN oN.NoN NN.NoN N N so oN.NNN NN.NN NN.NN NN.NeN NN.NNe N N No oo.NaN NN.NN NN.NN NN.NNN NN.eNe N N oo NN.oeN NN.oN No.NN NN.oeN eN.oNe N N No oN.NeN NN.NN NN.NN oN.NNN oN.NNN N N ooN No.oeN No.NN NN.NN eN.NNN NN.NNN N N oNN so.eNN so.NN oo.NN eN.NNN Ne.NNN N N NNN NN.NoN oo.NN N5.Ne NN.ooN NN.NNN N N eNN No.oNN Ne.NN oo.NN 4N.NNN oN.NNN N N on NN.NNN NN.NN NN.oo NN.oNN NN.eNs N N NNN .62 as as as as or .62 neon .62 .Nos nu .NsuosN: am .sNoooNs nu .sooaz am .usmNo: an easy insane sauna .NN tea N NoNNeN Nest .soNoNooasou Noon Nessa NsseNsaosN eN.< oNsoe LITERATURE CITED LITERATURE CITED Albertse, B.C., V.M. Pain and P.J. Garlick. 1979. Protein synthesis and breakdown in muscle and kidney of diabetic and insulin treated rats. Proc. Nutr. Soc. 39:19A. Allen, R.E., R.A. Merkel, and R.B. Young. 1979. Cellular aspects of muscle growth: Myogenic cell proliferation. J. Anim. Sci. 49:115. Anker, H.S. 1960. In the Plasma Proteins. Vol. 2. p. 267. F.W. Putnan (Ed.). Academic Press, New York. Arias, I.M., D. Doyle and R.T. Schimke. 1969. Studies on the synthesis and degradation of proteins of the endOplasmic reticulun of rat liver. J. Biol. Chem. 244:3303. Asatoor, A.M. and M.D. Armstrong. 1967. 3-Methylhistidine, a canponent of actin. Biochem. Biophys. Res. Com. 26:168. Ballard, F.J., F.M. Tomas and L.M. Stern. 1979. Increased turnover of muscle contractile proteins in Duchenne muscular dystrophy as assessed by 3-methylhistidine and creatinine excretion. Clin. Sci. 56:347. Bates, P.C., G.K. Grimble and D.J. Millward. 1979. The importance of non-skeletal muscle sources of urinary 3- methylhistidine in the rat. Proc. Nutr. Soc. 38:136A. Baxter, J.D. 1978. Mechanisms of glucocorticoid. Kidney Int. 14:330. Behnke, A.R., B.G. Feen and W.C. Welhan. 1942. Specific gravity of healthy men. 3. kn. Med. Assoc. 118:495. Bell, E.T. 1909. II. On the histogenesis of adipose tissue of the ox. Am. J. Anat. 9:412. Berg, R.T., B.B. Anderson and T. Liboriussen. 1978. Growth of bovin tissue. 1. Genetic influence on growth patterns of muscle, fat, and bone in young bulls, Anim. Prod. 26:246. 216 217 Berg, R.T., B.B. Anderson and T. Liboriussen. 1978. Growth of bovine tissue. 2. Genetic influence on muscle growth and distribution in young bulls. Anim. Prod. 27:51. Berg, R.T., B.B. Anderson and T. Liboriussen. 1978. Growth of bovine tissue. 3. Genetic influence on patterns of fat growth and distribution in young bulls. Anim. Prod. 27:63. Berg, R.T., B.B. Anderson and T. Liboriussen. 1978. Growth of bovine tissue. 4. Genetic influence on patterns of bone growth and distribution in young bulls. Anim. Prod. 27:71. Berg, R.J. and R.M. Butterfield. 1966. Muscle: bone ratio and fat percentage as measures of beef carcass composition. Anim. Prod. 8:1. Berg, R.T. and R.M. Butterfield. 1968. Growth patterns of bovin muscle, fat and bone. J. Anim. Sci. 27:611. Berg, R. T. and R. M. Butterfield. 1976. New Concepts of cattle growth. Sidney University Press, Sidney. Bergen, W.G. 1974. Protein synthesis in animal models. J. Anim. Sci. 38:1079. Bergen, W.G. I975. Nutritional regulation of macromolecular synthesis in muscle. Proc. Reciprocal Meat Conf. 28:247. Bieber, D.D., R.L. Saffle, L.D. Kanstra. 1961. Calculation of fat and protein content of beef fran specific gravity and moisture. J. Anim. Sci. 20:239. Bilmazes, C., C.L. Kien, D.K. Rohrbaugh, R. Uauy, J. Burke, H.N. Munro and V.R. Young. 1978. Quantitative contribution by skeletal muscle to elevated rates of whole- body protein breakdown in burned children as measured by N T-methylhiStidine output. Metab. 27:671. Block, W.D. and R.W. Hubbard. I962. Pmino acid content of rabbit urine and plasm. Arch. Bioch. Biophys. 96:557. Brody, S. 1945. Bioenergetics and Growth. Reinhold Publishing Co., New York. 218 Brown, C.J., J.C. Hillier and J.A. Whatley. 1951. Specific gravity as a measure of the fat content of pork carcass. J. Anim. Sci. 10:97. Brozek, J. and A. Keys. 1951. Evaluation of leanness— fatness in man: A survey of methods. Nutr. Abstr. and Rev. 20:247. Burleigh, LG. 1976. Toward more efficient meat animals: A theoretical consideration of constraints at the level of the muscle cell. In Meat Animals: Growth and Productivity. D. Lister, D.N. Rhodes, V.R. Fowler and M.F. Fuller (Eds.) Plenun Press,-' New York. Byers, F.M. 1978. Impact of runensin, limestone and energy level on corn silage energy utilization and canposition of growth of cattle. Midwest ASAS Meetings. #106. p. 41. (Abstr). Byers, F.M. 1979. Extraction and measurement of deuteriun oxide at tracer levels in biological fluids. Anal. Bioch. 98:208. Byers, F.M. 1979. Measurement of protein and fat accretion in growing beef cattle through isotope dilution procedures. OARDC Beef Res. Rep. Ans. series 79.1. p. 360 Byers, F.M. 1980. Systems of beef cattle feeding and management to regulate composition of growth to produce beef carcasses of desired composition. OARDC Beef Cattle Res. Rep. #259. p. l. Byers, F.M. and C. Parker. 1979. Level of nutrition and composition of growth of cattle varying in mature size. OARDC Beef Res. Rep. A050 series. 79‘10 p. 670 Byers, F.M., C.F. Parker and R.B. Rompala. I977. Nutri- tional regulation of growth patterns in steers genetically structured for differing mature size. Nat. ASAS. Meetings. p. 225 (Abstr.). Byers, F.M. and R.E. Rompala. 1979. Rate of protein deposi- tion in beef cattle as a function of mature size and weight and rate of empty body growth. QARDC Beef Res. Rep. A.S. 79.1. p. 360 219 Cahill, G.F. I970. Starvation in man. N. Eng. J. Med. 282:668. Cahill, G.F. I971. Physiology of insulin in man. Diabetes 20:785. Cahill, G.F. 1976. In Peptide Hormones. J.A. Parsons (Ed.) p. 85. Univ. Park Press. Baltimore. Callow, E.H. 1948. Comparative studies of meat. 11. The changes in the carcass during growth and fattening and their relation to the chemical canposition of the fatty and muscular tissue. J. Agr. Sci. 38:174. Callow, E.H. 1961. Comparative studies of meat. VII. A canparison between Hereford, Dairy Shorthorn and Friesian steers in four levels of nutrition. J. Agr. Sci. 56:265. Chan, L.and B.W. O'Malley. I978. Steroid hormone action: recent advances. Ann. Int. Med. 89:694. Cheek, D.B. and D.B. Hill. 1970. Muscle and liver cell growth: role of hormone and nutritional factors. Fed. Proc. 29:1503. Chrystie, 5., J. Horn, 1. Sloan, M. Stern, D. Noakes and M. Young. 1977. Effect of insulin on protein turnover in foetal lambs. Proc. Nutr. Soc. 36:118A. Clark, J.L., H.B. Hedrick and G.B. Thompson.“o 1976. Determination of body composition of steers by K. J. Anim. Sci. 42:352. Cowgill, R.W. and B. Freeburg. I957. The metabolism of methylhistidine canpounds in animals. Arch. Bioch. Biophys. 71:466. Crabtree, R.M., R.A. Houseman and M. Kay. 1974. The estimation of body composition in beef cattle by deuteriun oxide dilution. Proc. Nat. Soc. 33:74A. Crickenberger, R.G., D.G. Fox and W.T. Magee. 1978. Effect of cattle size and protein level on the utilization of high corn silage or high grain rations. J. Anim. Sci. 46:1748. 220 DaCosta, E. and R. Clayton. 1950. Studies on dietary restriction and rehabilitation. III. Interrelationships anong fat, water content and specific gravity of total carcass of abino rat. J. Nutr. 41:597. Danner, M. 1978. The effect of feeding system on the performance and carcass characteristics of yearling steers, steer calves and heifer calves. MS. Thesis. Michigan State University. Davis, S.L., U.S. Garrigus and F.C. Hinds. 1970. Metabolic effects of growth hormone and diethylstilbestrol in lanbs. II. Effect of daily ovine growth hormone injections on plasma metabolites and nitrogen-retention in fed lanbs. J. Anim. Sci. 30:236. Dinus, D.A., R.F. Brokken, K.P. Bovard and F.S. Runsey. 1976. Feed intake and carcass composition of angus and santa gertrudis steers fed diets of varying energy concentrations. J. Anim. Sci. 42:1089. Domingo, E.A., T.E. Trigg and J.H. Topps. 1972. Estimation of body composition of sheep by isotopic dilution technique. I. Exchangeable potassiun. Proc. Nutr. Soc. 32:20A. Edelman, 1.5. 1952. Exchange of water between blood and tissue. Characteristics of deuteriun oxide equilibration in body water. Am. J. Physiol. 171:279. Elsley, F.W., I. McDonald and V.R. Fowler. The effect of plane of nutrition on the carcasses of pigs and lanbs when variations in fat content are excluded. Anim. Prod. 6:141. Elzinga, M., J.H. Collins, W.M. Kuehl and R.S. Adelstein. 1973. Canplete anino acid sequence of actin of rabbit skeletal muscle. Proc. Nat. Acad. Sci. 70:2687. Eversole, D.E. 1978. Growth and muscle development of feedlot cattle of different genetic backgrounds. Ph.D. Thesis, Michigan State University. Farrell, D.J. and T.F. Reardon. 1972. Undernutrition in grazing sheep III. Body canposition and its estimation in vivo. Aust. J. Agric. Res. 23:511. 221 Fashakin, J.B. and D.M. Hegsted. 1970. Protein degradation and synthesis in animo-acid deficiencies. Nature 228:1313. Flaim, K.E., J.B. Ki and I..S. Jefferson. 1978. Effects of thyroxine on protein turnover in rat skeletal muscle. An J. Physiol. 235:E231. Foot, J.Z. and J.F.D. Greenhalgh. I970. The use of deuteriun oxide space to detennine the anount of body fat in pregnant blackface ewes. Brit. J. Nutr. 24:815. Fowler, V.R. 1968. Body development and some problems of its evaluation. In Growth and Development of Marrmals. G.A. Lodgen and G.A. Larming (Eds.). Plenun Publishing Corp., New York. Fralm, R.R., L15. Walters and C.R. McLellan. 1971. Evaluation of K count as a predictor of muscle in yearling beef bulls. J. Anim. Sci. 32:463. Frayn, K.N. and P.F. Maycock. 1979. Regulation of protein metabolism by a physiological concentration of insulin in mouse soleus and extensor digitorun longus muscles. Effects of starvation and scald injury. Biochem J. 184:323. Funabiki, R., J. Watanabe, N. Nishizawa, S. Hareyana. 1976. Quantitative aspect of the myofibrillar protein turnover in transient state on dietary protein depletion and repletion revealed by urinary excretion of NT - methylhistidine. Biochim. Biophys. Acta. 451:143. Gan, J.C. and H. Jeffay. 1967. Origins and metabolism of the intracellular anino acid pools in rat liver muscle. Biochim. Biophys. Acta. 148:448. Garrett, W.N. 1968. Experiences in the use of body density as an estimator of body composition of animals. In Body Composition in Animals and Man. Nat. Acad. Sci. Washington D.C. Garrett, W.M. 1979. Influence of time of access to feed and concentrate roughage ratio on feedlot performance of steers. California Feeder Day, p. 11. Garrett, W.N. and N. Hirman. I969. Re-evaluation of the relationship between carcass density and abody canposition of beef steers. J. Anim. Sci. 28:1. 222 Garrett, W.N., J.H. Meyer and C.P. Lofgreen. I959. The comparative energy requirements of sheep and cattle for maintenence and gain. J. Anim. Sci. 18:528. Gest, H.M., M.D. Kanen and J.R. Reiner. I947. The theory of isotope dilution. Arch. Biochan. 12:273. Glass, R.D. and D. Doyle. 1972. On the measurement of protein turnover in animal cells. J. Biol. Chem. 247:5234. Goldberg, A.L., M. Tischler, G. DeMartino and G. Griffin. 1980. Hormonal regulation of protein degradation and synthesis in skeletal muscle. Fed. Proc. 39:31. Goldfine, I.D. 1978. Insulin receptors and the site of action of insulin. Life Sci. 23:2639. Goldspink, G. 1972. Postembryonic growth and differentiation of striated muscle. In The Structure and Function of Muscle. Vol. 1., G.H. Bowin (Ed.), Academic Press Inc., New York. Goldstein, S. and W.J.l Reddy. 1967. Effect of insulin on the incorporation of C—Ieucine into rat caudofemoralis protein. Biochim. Biophys. Acta. 141:310. Grigsby, J.S., W.G. Bergen and R.A. Merkel. 1976. The effect of testosterone on skeletal muscle development and protein synthesis in rabbits. Growth 40:303. Gruner, H.D., H. Koblet and C. Wodard. I961. Phenylalanine metabolism in the phenylpyruvic condition. 1. Distribution, pool size, and turnover rate in hunan phenylketouria. J. Clin. Invest. 40:1758. Guenther, J.J., D.H. Bushnan, L.S. Pope and R.D. Morrison. 1965. Growth and development of the major carcass tissue in beef calves from weaning to slaughter, with reference to the effect of plane of nutrition. J. Anim. Sci. 24:1184. Haecker, T.L. 1920. Investigations in beef production. Minn. Agr. Exp. Sta. Res. Bull. 193. Haigh, C.P. and H. Schnieden. 1956. Virtual deuteriun oxide space (total body water) in nonnal and protein deficient rats. J. Physiol. 131:377. 223 Hankins, O.G. and P.E. Howe. 1946. Estimation of the composition of beef carcasses and cuts. U.S.D.A. Tech. Bull. 926. Harmond, J. 1952. Farm Animals, Their Breeding, Growth and Inheritance. Edward Arnold and Co., London. Harpster, H.W. 1978. Energy requirements of cows and the effect of sex, selection, frame size, and energy level on performance of calves of four genetic types. Ph.D. Thesis, Michigan State University. Hardy, M.F., C.I. Harris, 5. Perry and D. Stone. Occurence and formation of the N -methyl-lysines in myosin and the myofibrillar proteins. Biochem. J. 120:653. Harris, C.I. 1981. Reappraisal of the quantitative importance of non-skeletal-muscle source of NT - methylhistidine in urine. Biochem. J. 194:1011. Harris, C. I. and G. Milne. I977. The unreliability of urinary 3-methylhistidine excretion as a measure of muscle protein degradation in sheep. Proc. Nutr. Soc. 36:138A. Harris, C.I. and G. Milne. 1979. Urinary excretion of 3- methylhistidine in cattle as a measure of muscle protein degradation. Proc. Nutr. Soc. 38:llA. Harris, C.I. and G. Milne. 1980a. The urinary excretion of NT -methylhistidine in sheep: an invalid index of muscle protein breakdown. Br. J. Nutr. 44:129. Harris, C.I. and G. Milne. 1980b. The occurrence of the NT -methylhistidine containing dipeptide, balenine, in muscle extracts of various marrmals. Biochem. Soc. Trans. 8:552. Harris, C.I. and G. Milne. 1981a. The urinary excretion of NE -methylhistidine by cattle: validation as an index of muscle protein breakdown. Br. J. Nutr. 45:411. Harris, C.I. and G. Milne. 1981b. The inadequacy of urinary N‘r -methylhistidine excretion in the pig as a measure of muscle protein breakdown. Br. J. Nutr. 45:423. 224 Harris, C.I., G. Milne, G.B. Lobley and G.A. Nicholas. I977. 3-methylhistidine as a measure of skeletal-muscle protein catabolism in the adult new zealand white rabbit. Biochan. Soc. Trans. 5:1977. Haverberg, L.N. I975T. Use of NT -Methylhistidine (3- methylhistidine) as an index of in vivo muscle protein degradation rates. Ph.D. Thesis, Massachusetts Institute of Technology. Haverberg, L.N., L. Deckelbaun, C. Bilmazes and H.N. Munro. I975. Myofibrillar protein turnover and urinary NT - methylhistidine output. Biochem. J. 152:503. Haverberg, L.N., H.N. Monro and V.R. Young. 1974. Isolation and quantitation of NT -methylhistidine in actin and myosin of rat skeletal muscle: Use of pyridine elution of protein hydrolysates on ion-exchange resin. Biochim. Biophys. Acta 371:226. Haverberg, L.N., P.T. Onstedt, H.N. Munro and V.R. Young. 1975. NT-methylhistidine content of mixed proteins in various rat tissues. Biochim. Biophys. Acta. 405:67. Hay, A.M. and J.C. Waterlow. I967. The effects of alloxan diabetes on muscle and liver protein synfpeiiis in the rat, C measured by constant infusion of L-[ lysine. J. Physiol. 191:111. Henrickson, R.L., L.S. Pope and R.F. Hendrickson. 1965. Effect of rate of gain of fattening beef calves on carcass canposition. J. Anim. Sci. 24:507. Hevesy, G. and E. Hofer. I934. Elimination of water from the hunan body. Nature 134:879. Hill,D.E., A.B. Holt, A. Parra and D.B. Clark. 1970. The influence of protein-calorie versus calorie restriction on the body composition and cellular growth of muscle and liver in weanling rats. Johns Hopkins Med. J . 127:146. Hjalmarson, A.C., D.E. Rannels, R. Kao and H.E. Morgan. 1975. Effects of hypophysectany, growth hormone and thyroxine on protein turnover in heart. J. Biol. Chem. 250:4556. 225 Holbrook, I.B.,E. Gross and M.H. Irving. 1979. NT - methylhistidine in hunan skeletal and smooth muscle proteins. Br. J. Nutr. 41:15. Happer, T.H. 1944. Methods of estimating the physical and chanical canposition of cattle. J. Agr. Res. 68:239. Howarth, R.E. 1972. Influence of dietary protein on rat skeletal muscle growth. J. Nutr. 102:37. Huszar, G. and M. Elzinga. I972. Hanologous methylated and normethylated histidine peptides in skeletal and cardiac myosins. J. Biol. Chem. 247:745. Huxley, J. 1932. Problems of Relative Growth. Methuen, London. Hytten, P.E., N. Taggart and W.Z. Billewicz. 1962. The estimation of small concentrations of deuteriun oxide in water by the falling drop method. Phys. Med. Biol. 6:415. Jefferson, L.S., D.E. Rannels, B.L. Munger and H.E. Morgan. ' 1974. Insulin in the regulation of protein turnover in heart and skeletal muscle. Fed. Proc. 33:1098. Jesse, G.W., G.B. Thompson, J.L. Clark, H.B. Hedrick and K.C. Weimer. 1976a. Effects of ration energy and slaughter weight on canposition of empty body and carcass gain of beef cattle. J. Anim. Sci. 43:418. Jesse, G.W., G.B. Thompson, J.L. Clark, K.G. Weimer and D.P. Hutcheson. 1976b. Effects of various ratios of corn and corn silage and slaughter weight on the performance of steers individually fed. J. Anim. Sci. 43:1049. Johnson, E.R. 1974. The growth of muscle, bone, fat and connective tissue in cattle fran 150 days gestation to 84 days old. Aust. J. Agr. Res. 25:1037. Johnson, P., C.I. Harris and S.V. Perry. 1967. 3- methylhistidine in actin and other muscle protein. Biochem. J. 105:361. Johnson, P., G.B. Lobley and S.V. Perry. 1969. Distribution and biological role of 3-methylhistidine in actin and myosin. Biochem. J. 114:34P. 226 Jones, S.D.M., M.A. Price and R.T. Berg. 1978. A review of carcass density, its measurement and relationship with bovine carcass fatness. J. Anim. Sci. 46:1151. Kassenafs, A.A.H., J. deGraeff and A.T. Kouwenhoven. 1960. N —glycine studies of protein synthesis during refeeding in anorexia nervosa. Metab. Clin. Expt. 9:831. Kerr, D.S., M.C.G. Stevens, H.M. Robinson and D.I. Picou. 1973. In Endocrine Aspects of Malnutrition. L.I. Gardner and P. Anacher. (eds.) Kroc. Foundation, Santa Ynez, Calif. Klosterman, E.W., P.G. Althouse, and V.R. Cahill. 1965. Effect of corn silage or ground ear corn full fed at various stages of growth and fattening upon carcass composition of beef cattle. J. Anim. Sci. 24:454. Klosterman, E.W. and C.P. Parker. 1976. Effect of size, breed and sex upon feed efficiency in beef cattle. Ohio Agr. Res. Dev. Ctr. Res. Bull. 1088. Koch, A.R., R.P. Kromann and T.R. Wilson. 1979. Growth of body protein, fat and skeleton in steers fed on three planes of nutrition. J . Nutr. 109:426. Korner, A. 1967. Ribonucleic acid and hormone control of protein synthesis. Prog. Biophys. Mol. Biol. 17:61. Kostyo, J.L. and D.P. Nutting. 1973. Acute in vivo effects of growth honnone on protein synthesis in various tissue of hypophysectanized rats and their relationship to levels of thymidine factor and insulin in the plasma. Horm. Metab. Res. 5:167. Kostyo, J.L. and C.R. Reagan. 1976. The biology of growth hormone. Pharmacol. Ther. 2:591. Kostyo, J.L. and J.B. Schnidt. 1962. Hormonal specificity of the in vitro action of growth hormone on anino acid transport into rat muscle. Endocrinol. 70:381. Kraybill, H.F., H.L. Bitter, and O.G. Hankins. 1952. Body canposition of cattle. II. Determination of fat and water content fran measurement of body specific gravity. J. Appl. Physiol. 4:575. 227 Kraybill, H.F., E.R. Goode, R.S.B. Robertson, and H.S. Sloane. 1953. In vivo measurement of body fat and body water in swine. J. Appl. Physiol. 6:27. Kraybill, H.F., O.G. Hankins and H.L. Bitter. 1951. Body composition of cattle 1. Estimation of body fat from Ineasuranent in vivo of body water by use of antipyrine. J. Appl. Physiol. 3:681. Krysik, B., J.P. Vergnes and J.R. McManus. 1971. Enzymatic methylation of skeletal muscle contractile proteins. Arch. Biochan. Biophys. 146:34. Kuehl, W.M. and R.S. Adelstein. 1970. The absence of 3- methylhistidine in red, cardiac and fetal myosins. Biochem. Biophys. Res. Conmun. 39:956. Kurihara, K. and I. G. Wool. 1968. Effect of insulin on the synthesis of sarcoplasmic and ribosomal proteins of muscle. Nature. 219:721. Lee, Y.B., R.G. Kauffman and R.H. Grurmer. 1973. Effect of early nutrition on the development of adipose tissue in the pig. 1. Age constant basis. J. Anim. Sci. 37:1312. Lee, Y.B., R.G. Kauffman and R.l-l. Grm'mer. 1973. Effect of early nutrition on the development of adipose tissue in the pig. 11. Weight constant basis. J. Anim. Sci. 37:1319. Little, D.A. and J.G. Morris. 1972. Prediction of the body canposition of live cattle. J. Agric. Sci. 78:505. Lobley, G.E. and J.M. Lovie. 1979. The synthesis of myosin, actin and the major protein fractions in rabbit skeletal muscle. Biochem. J. 182:867. Loeb, J.N. 1976. Corticosteroids and Growth, New Engl. J. Med. 295:547. Lofgreen, C.P. 1965. A canparative slaughter technique for determining net energy values with beef cattle. 3rd Symposiun on Energy Metabolism. K.L. Blaxter (ed.). Academic Press, London. 228 Lofgreen, G.P. and W.N. Garrett. 1968. A system for expressing net energy requirements and feed values for growing and finishing beef cattle. J. Anim. Sci. 27:793. Lofgreen, G.P. and K.K. Otagaki. 1960. The net energy of blackstrap molasses for fattening steers as determined by a comparative slaughter technique. J. Animl. Sci. 19:392. Lol'man, T.G., B.C. Breidenstein, A.R. Twardock, G.W. Smith and H.W. Norton. 1966. Symposiun on atomic energy in animals. 1410' Estimation of carcass lean muscle mass in steers by K measurements. J. Anim. Sci. 25:1218. Lolman, T.G. and H.W. Ngrton. 1968. Distribution of potassiun in steers by K measurement. J. Anim. Sci. 27:1266. Long, C.L., L.M. Haverberg, V.R. Young, J.M. Kinney, H.N. Munro and J.W. Geiger. 1975. Metabolism of 3- methylhistidine in man. Metab. 24:929. Long, C.N.H., B. Katzin and E.G. Try. 1940. The adrenal cortex and carbohydrate metabolism. Endocrinol. 26:309. Manchester, K.L. 1970. In Mam'nalian Protein Metabolism. H.N. Munro (ed.). Academic Press, New York. Manchester, K.L. 1976. In Protein Metabolism and Nutrition. D.J. Cole, K.N. Boorman, P.J. Buttery, D. Lewis, R.J. Neale and H. Swan (eds.). Butterworth, London. Manchester, K.L. and P.G. Young. 1959. Hormones and protein biosynthesis in isolated rat diaphram. J. Endocrinol. 18:381. Manchester, K.L. and P.G. Young. 1959. Location of 1QC in psotein from isolated rat ld‘iaphragm incubated in vitro with C-amino acids and with (:02. Biochem. J. 72:137. Marchello, J.H. and W.H. Hale. 1976. Nutrition and management of runinant animals related to reduction of fat content in meat and milk. In Fat Content and Composition of Animal Products. Nat. Acad. Sci., Washington, D.C. Mayer, M. and F. Rosen. 1977. Interaction of glucocorticoids and androgens with skeletal muscle. Metab. 26:937. 229 Maynard, L.A. and J.K. Loosli. 1969. Animal Nutrition. McGraw-Hill Book Co., New York. McMeekan, C.P. 1940. Growth and development in the pig, with special reference to carcass quality characteristics. II. The influence of the plane of nutrition on growth and developnent. J. Agr. Sci. 30:387. McMeekan, C.P. 1959. Principles of Animal Production. Whitcornbe and Tombe, Ltd., London. Meyer, J.H., G.P. Lofgreen and W.N. Garrett. 1960. A proposed method for removing sources of error in beef cattle feeding experiments. J. Animl Sci. 19:1123. Milne, G. and C.I. Harris. 1978. The inadequacy of urinary 3-methy1histidine excretion as an index of muscle protein degradation in the pig. Proc. Nutr. Soc. 37:18A. Millward, D.J. 1970a. Protein turnover in skeletal muscle. 1. The measurements of rates ofwsynthesis and catabolism of skeletal muscle protein using C-NaZCO3 to label protein. Clin. Sci. 39:577. Millward, D.J. 1970b. Protein turnover in skeletal muscle. II. The effect of starvation and a protein-free diet on the synthesis and catabolism of skeletal muscle protein in comparison to liver. Clin. Sci. 39:591. Millward, D.J., P.C. Bates, G.K. Grimble, J.G. Brown, M. Nathan and M.J. Rennie. Quantitative importance of non- skeletal-muscle sources of NT -methyl-histidine in urine. Biochem. J. 190:225. Millward, D.J., P.J. Garlick. W.P.T. James, P.M. Sender and J.C. Waterlow. 1976a. Protein turnover. In Protein Metabolism and Nutrition. D.J. Cole, K.M. Boorman, P.J. Buttery, D. Lewis, R.J. Neale and H. Swan (eds.). Butterworth, Boston. Millward, D.J., P.J. Garlick, D.C. Nnanyelugo and J.C. Waterlow. 1976b. The relative importance of muscle protein synthesis and breakdown in the regulation of muscle mass. Biochem. J. 156:185. Millward, D.J. and J.C. Waterlow. 1978. Effect of nutrition on protein turnover in skeletal muscle. Fed. Proc. 37:2283. 230 Morales, M.F., E.N. Rathbun, R.E. Smith and N. Pace. 1945. Studies on body canposition. II. Theoretical considerations regarding the major tissue cornponents with suggestions for application to man. J. Biol. Chem. 158:677. Morgan, H.E. and K. Wildenthal. 1980. Protein Turnover in heart and skeletal muscle. Fed. Proc. 39:7. Moore, F.D. 1946. Determination of total body water and solids with isotopes. Science 104:157. Moulton, C.R., P.F. Trowbridge and L.D. Haigh. 1922. Studies in animal nutrition. III. Changes in the chemical composition on different planes of nutrition. Mo. Agr. Exp. Sta. Res. Bull. 55. Mukhoty, H. and R.T. Berg. 1971. Influence of breed and sex on the allometric growth patterns of major bovin tissues. Anim. Prod. 13:219. Munck, A. 1971. Glucocorticoid inhibition of glucose uptake by peripheral tissue: old and new evidence, molecular mechanisms, and physiological significance. Perspect. Biol. Med. 14:265. Munro, H.N. 1964. In Mamnalian Protein Metabolism. H.N. Munro and J.B. Allison (eds.). Academic Press, New York. Nagabhushan, V.S. and B.S. Narasinga. 1978. Studies on 3- methylhistidine metabolism in children with protein-energy malnutrition. Am. J. Clin. Nutr. 31:1322. Neuberger, A. and P.F. Richards. 1964. In Mamnalian Protein Metabolism. H.N. Munro and J.B. Allison (eds.). Academic Press, New York. Nishizawa, N., T. Noguchi, S. Hareyama and R. Funabiki. 1977b. Fractional flux rates of NT -methy1histidine in skin and gastrointestine: the contribution of these tissues to urinary excretion of NT -methylhistidine in the rat. Brit. J. Nutr. 39:149. Nishizawa, N., M. Shimbo, S. Hareyarna and R. Funabiki. 1977a. Fractional catabolic rates of Inyosin and actin esthnated by urinary excretion ofNT 4nethylhistidine: the effect of dietary protein level on catabolic rates under conditions of restricted food intake. Brit. J. Nutr. 37:345. \ J \. 231 Nishizawa, N., M. Shimbo, T. Naguchi, S. Hareyama and R. Funabiki. 1978. Effect of starvation, refeeding and hydrocortisone adninistration on turnover of nwofibrillar protein esthnated by urinary excretion of NT - unethylhistidine in the rat. Agric. Biol. Chan. 42:2083. Nishizawa, N., Y. Toyoda, T. Noguchi, S. Hareyama, H. Itabashi and R. Funabiki. 1979. NT 4nethylhistidine content of organs and tissues of cattle and an attanpt to esthnate fractional catabolic and synthetic rates of nwofibrillar proteins of skeletal muscle during growth by measuring urinary output of NT 4nethylhistidine. Brit. J. Nutr. 42:247. Ogata, E.S., S.K.H. Foung and‘M.A. Holliday. 1978. The effects of starvation and refeeding on Inuscle protein synthesis and catabolimn in the young rat. J. Nutr. 108:759. Onstedt, P.T., R. Kihlberg, P. Tingvall and A. Shenkin. 1978. Effect of dietary protein on urinary excretion of 3- nmthylhistidine in rat. J. Nutr. 108:1877. Oppenhehner, J.H. 1979. Thyroid honnone action at the cellular level. Science 203:971. Oser, B.L. 1965. Hawk's Physiological Chemistry. McGraw- Hill, New York. Pace, N., L. Kline, H.K. Schachman and M. Harfenist. 1947. Studies on body composition. IV. The use of radioactive hydrogen in nwasuranent in vivo of total body water. J. Biol. Chem. 168:459. Palsson, H. 1955. Confonnation and body canposition. In Progress in the Physiology of Farm Animals. J. Harrmond (ed.). Butterworths Publications, London. Palsson, H. and J.B. Verges. 1952a. Effects of the plane of nutrition on growth and the developnent of carcass quality in lanbs. I. The effects of high and low planes of nutrition at different ages. J. Agr. Sci. 42:1. Palsson, H. and J.B. Verges. 1952b. Effects of the plane of nutrition on growth and developnent of carcass quality in lanbs. Part 11. Effects on lanbs of 30 lb. carcass wt. J. Agr. Sci. 42:93. 232 Panaretto, B.A. 1963. Body composition in vivo. III. The composition of living runinants and its relation to the tritiated water spaces. Aust. J. Agric. Res. 14:944. Panaretto, B.A. 1964. Body composition in vivo. VI. The composition of ewes during prolonged undernutrition. Aust. J. Agr. Res. 15:771. Panaretto, B.A. and A.R. Till. 1963. Body composition in vivo. 11. The composition of mature goats and its relationship to the antipyrine, tritiated water and N- acetyI-4 amino-antipyrine space. Aust. J. Agric. Res. 14:923. Pearson, A.M. 1965. Body composition. In Newer Methods of Nutritional Biochemistry. A. Albanese (ed.) Academic Press, New York. Pearson, A.M., R.W. Purchas and E.P. Reineke. 1968. Theory and potential usefulness of body density as a predicator of body composition. In Body Composition in Animals and Man. Nat. Acad. Sci. Wash. D.C. Perry., B.N. 1974. Protein turnover in skeletallnuscle of piglets. Br. J. Nutr. 31:35. . Perry, T.W. and W.M. Beeson. 1976. Ratios of corn silage for finishing beef cattle. J. Animl Sci. 42:549. Phillips, L.S. and R. Vassiloupoulou-Sellin. 1979. Nutritional regulation of sanatanedin. Am. J. Clin. Nutr. 32:1082. Pinson, E.A. 1952. Water exchange and barriers as studied by the use of hydrogen isotopes. Physiol. Rev. 32:123. Pool, B. 1971. The kinetics of disappearance of labeled leucine from the free leucine pool of rat liver and its effect on the apparent turnover of catalase and other hepatic proteins. J. Biol. Chem. 246:6587. Powell, W.E. and D.L. Huffman. 1968. An evaluation of quanitative estimates of beef carcass cornposition. J. Anim. Sci. 27:1554. Prior, R.L., R.H. Kohlmeier, L.V. Cundiff, M.E. Dikeman and J.D. Crouse. 1977. Influence of dietary energy and protein on growth and carcass composition in different biological types of cattle. J. Anim. Sci. 45:132. 233 Radin, N.S. 1947. Isotope techniques in biochanistry. Nucleonics. 1(2):48. Rathbun, E.N. and N. Pace. 1945. Studies on body composition. 1. The determination of total body fat by means of the body specific gravity. J. Biol. Chem. 158:667. Rattray, P.V., W.N. Garrett, N. Hirman and N.E. East. 1974. Energy cost of protein and fat deposition in sheep. J. Anim. Sci. 38:378. Reeds, P.J., K.A. Munday and M.R. Turner. 1971. Action of insulin and growth hormone on protein synthesis in muscle from non-hypophysectanized rabbits. Biochem. J. 125:515. Reid, J.T., A. Bensadown, L.S. Bull, J.H. Burton, P.A. Gleeson, I.K. Han, Y.D. Joo, D.E. Johnson, W.R. McManus, C.L. Paladines, J.W. Stroud, H.F. Tyrell, B.D.H. Van Niekerk and G.W. Wellington. 1968b. Some pecularities in the body composition of animals. In Body Composition in Animals and Man. Nat. Acad. Sci. 1598:19. Reid, J.T., G.H. Wellington and H.O. Dunn. 1955. Some relationships anong the major chemical components of the bovine body and their application to nutritional investigations. J. Dairy Sci. 38:1344. Schimke, R.T. 1970. Marrmalian Protein Metabolism. Vol. IV. Chap. 32. H.N. Munro (ed.). Academic Press, New York. Schloerb, P.R., B.J. Friis-Hansen, I.S. Edelman, D.B. Sheldon, and F.D. Moore. 1951. The measurement of deuteriun oxide in body fluids by the falling drop method. J. Lab. Clinc. Med. 37:653. Schlose, E. 1911. Pathologie des watchstuns. S. Karger, Berlin. In Animal Nutrition. L.A. Maynard and J.K. Loosli (eds.). McGraw-Hill Book Co., New York. Sender, P.M. and P.J. Garlic. 1973. Synthesis rates of Protein in the Langendorf-perfused rat heart in the presence and absence of insulin, and in the working heart. Biochan. J. 132:603. Searle, T.W. 1970a. Body composition in lambs and young sheep and its prediction in vivo from tritiated water space and body weight. J. Agric. Sci. 74:357. 234 Searle, T{WL 1970b. Prediction of body canposition of sheep fran tritiated water space and body weight-tests of published equations. J. Agric. Sci. 75:497. Shipley, R.A. and R.E. Clark. 1972. Tracer Methods for In Vivo Kinetics. Academic Press, New York. Simon, G. 1965. Histogenesis. In Handbook of Physiology. Section 5: Adipose Tissue. p. 101-107. A.E. Renold and G.F. Cahill, Jr. (eds.). Pm. Physiological Society, Wash. D.C. Smith, G.M., J.D. Crouse, R.W. Mandigo and K.L. Neer. 1977. Influence of feeding regime and biological type on growth composition and palatability of steers. J. Anim. Sci. 45:236. Snedecor, G.W. and W.G. Cochran. 1967. Statistical Methods. Ames: Iowa State University Press. Soberman, R., B.B. Brodie, B.B. Lerry, J. Axelrod, V. Hollander and J.M. Steele. 1949. The use of antipyrine in the measurements of total body water in man. J. Biol. Chem. 179:31. Spence, G.A., and F.M. Hansen-Smith. 1978. Cornparison of the chemical and biochemical CMposition of thirteen muscles of the rat after dietary protein restriction. Br. J. Nutr. 39:647. Stanley, E.G. and R. McCall. 1945. A study of performance in Hereford cattle. Arizona Agr. Exp. Sta. Bull. 109:35. Stephen, J.M.L. and J. Waterlow. 1966. Use of Carbon-14- labelled Arginine to measure the catabolic rate of seer and liver proteins and the extent of anhno acid recycling. Nature 211:978. Sterling, K. 1979. Thyroid hormone action at the cell level. I. Thyroid hormone action at the cell level. II. New Engl. J. Med. 300:117,173. Stonaker, H.H., M.H. Hazaleus and 5.5. Wheeler. 1952. Feedlot and carcass characteristics of individually fed cornprest and conventional type Hereford steers. J. Anim. Sci. 11:17. 235 Stromer, M.H., D.E. Goll, R.B. Young, R.M. Robinson, and F.C. Parrish, Jr. 1974. Ultrastructural features of skeletal muscle differentiation and development. J. Anim. Sci. 38:1111. Swanson, E.W. and N.W. Neathery. 1956. Body water estimations with identical twin dairy cattle using antipyrine. J. Anim. Sci. 15:1300. Swick, R.W. 1958. Measurement of protein turnover in rat liver. J. Biol. Chem. 231:751. Swick, R.W. and M.M. Ip. l1,974. Measurement of protein turnover in rat liver with [ C] carbonate. J. Biol. Chem. 249:6836. Swick, R.W. and H. Song. 1974. Turnover rates of various muscle proteins. J. Anim. Sci. 38:1150. Tallan, H.H., W.H. Stein and S. Moore. 1954. 3- methylhistidine, a new amino acid from hunan urine. J. Biol. Chem. 206:825. Till, A.R. and A.M. Downes. 1962. The measurement of total body water in the sheep. Aust. J. Agric. Res. 13:335. Trigg, T.E., E.A. Domingo, and J.H. Topps. 1972. Estimation of body canposition of sheep by isotopic dilution technique 2. Deuteriun oxide and tritiated water. Proc. Nutr. Soc. 32:21A. Turner, M.R. and K.A. Munday. 1976. Hormonal control of muscle growth. In Meat Animals Growth and Productivity. D. Lister, D.N. Rhodes, U.R. Fowler, and M.F. Fuler (eds.). Plenun Press, New York. Turner, M.R., P.J. Reed, and K.A. Munday. 1976. Action of growth hormone in vitro on the net uptake and incorporation into protein of amino acids in muscle from intact rabbits given protein-deficient diets. Br. J. Nutr. 35:1. Wagner, J.F. and E.L. Veenhuizen. 1978. Growth performance, carcass deposition and plasma hormone levels in wether lambs when treated with growth hormone and thyroprotein. Am. Soc. An. Sci. A. 454. p. 397. (Abstr.). Wallace, L.R. 1948. The growth of lambs before and after birth in relation to the level of nutrition. J. Agr. Sci. 38:243. 236 Ward, L.C. and P.J. Buttery. 1978. NT -Methylhistidine-An index of the true rate of myofribillar degradation? An appraisal. Life Sciences. 23:1103. Waterlow, J.C. 1968. Observations on the mechanism of adaptation to low protein intakes. Lancet. ii:109l. Waterlow, J.C. 1969. Marrmalian Protein Metabolism. Vol. III. Chap. 32. H.N. Munro (ed.). Academic Press, New York. Waterlow, J.C. 1970 Total protein turnover in animals and man. Nutr. Revs. 28:115. Waterlow, J.C., P.J. Garlick and D.J. Millward. 1978. Protein turnover in mamnalian tissue and in the whole body. North-Holland Pub. Co., Amsterdam. Waterlow, J.C. and J.M.L. Stephen. 1968. The effect of low protein diets on the turnover rates of serun, liver and musclelaroteins in the rat, measured by continuous infusion of L- C lysine. Clin. Sci. 35:287. Weiss, G.M., D.G. Topel, R.C. Ewan, R.E. Rust, and L.L. Christian. 1971. Growth comparison of a muscular and fat strain of swine. I. Relationship between muscle quality and quantity, plasma lactate and l7-hydroxycorticosteroids. J. Anim. Sci. 32:1119. Wellington, G.H., J.T. Reid, L.J. Bratzler, and J.I. Miller. 1956. Use of antipyrine in nutritional and meats studies with cattle. J. Anim. Sci. 15:76. Whiting, F., C.C. Balch, and R.C. Campling. 1960. Some problens in the use of antipyrine and N-acetyle-4- aminoantipyrine in the determination of body water in cattle. Brit. J. Nutr. 14:519. Winick, M. and A. Noble. 1965. Quantitative changes in DNA, RNA and protein during prenatal and postnatal growth in the rat. Develop. Biol. 12:451. Winick, M. and A. Noble. 1966. Cellular response in rats during malnutrition at various ages. J. Nutr. 89:300. Woody, H.D. 1978. Influence of ration grain content on feedlot performance and carcass characteristics. Ph.D. Thesis, Michigan State University. 237 Wool, LG. and M.E. Krahl. 1959. Incorporation of ll‘C-arnino acids into protein of isolated diaphrams: an effect of insulin independent of glucose entry. Am. J. Physiol. 196:961. Wool, I.G., W.S. Stirewalt, K. Kurihara, R.B. Low, P. Bailey and D. Oyer. 1968. II. Hormones and metabolic function: Mode of action of insulin in the regulation of protein biosynthesis in muscle. Recent Progr. Horm. Res. 24:139. Wu, H. and S.E.ISSnyderman. 1950. Rate of excretion of N15 after feeding N -labeled l-aspartic acid inlnan. J. Gen. Physiol. 34:339. Yeh, J.K. and J.F. Aloia. 1978. Preliminary report: dietary consituents and somatomedin activity. Metab. 27:507. Young, R.B. and R.E. Allen. 1979. Transitions in gene activity during development of muscle fibers. J. Anim. Sci. 48:837. Young, R.B., T.R. Miller and R.A. Merkel. 1978. Clonal analysis of satellite cells in growing mice. J. Anim. Sci. 46:1241. Young, R.B., T.R. Miller and R.A. Merkel. 1979. Myofibrillar protein synthesis and assembly in satellite cell cultures isolated from skeletal muscle of mice. J. Anim. Sci. 48:54. Young, V.R. 1970. The role of skeletal and cardiac muscle in the regulation of protein metabolism. In Mamnalian Protein Metabolism. H.N. Munro (ed.). Academic Press, New York. ’ Young, V.R. 1980. Honnonal control of proteinlnetabolisn, with particular reference to body protein gain. In Protein Deposition in Anhnals. P.J. Buttery and D.B. Lindsay (eds.). Butterworth, Boston. Young, V.R. and S.D. Alexis. 1968. In vitro activity of ribosomes and RNA content of skeletal muscle in young rats fed adequate or low protein. J. Nutr. 96:255. Young, V.R., S.D. Alexis, B.S. Baliga, H.N. Munro and W. Muecke. 1972. Metabolism of administered 3- methylhistidine. Lack of muscle transfer ribonucleic acid charging and quantitative excretion as 3-methylhistidine and itsNacetyl derivative. J. Biol. Chem. 247:3592. 238 Young, V.R., B.S. Baliga, S.D. Alexis and H.N. Munro. 1970. Lack of in vitro binding of 3-methylhistidine to transfer RNA by amino acyl ligases from skeletal muscle. Biochim. Biophys. Acta. 199:297. Young, V.R., S.C. Chen and J. MacDonald. 1968. The sedimentation of rat skeletal-muscle ribosomes. Effect of hydrocortisone, insulin and diet. Biochen. J. 106:913. Young, V.R., L.N. Haverberg, C. Bilmazes and H.N. Munro. 1973. Potential use of 3-methylhistidine excretion as an index of progressive reduction in muscle protein catabolism during starvation. Metab. 22:1429. Young, V.R. and H.N. Munro. 1978. NT -methylhistidine (3- methylhistidine) and muscle protein turnover: an overview. Fed. Proc. 37:2291. Young, V.R. and M.G. Pluskal. 1977. In Protein Metabolism and Nutrition. Europ. Assoc. Anim. Prod. Public. No. 2. Wageningen, Holland. Young, V.R. and N.S. Scrimshaw. 1971. The physiology of starvation. Scient. Am. 225:13. Young, V.R., S.C. Strothers and G. Vilaire. 1971. Synthesis and degradation of mixed proteins and composition changes in skeletal muscle of malnourished and refed rats. J. Nutr. 101:1379. Zapf, J., E. Rinderkneckt, R.E. HLmbel and E.R. Froesch. 1978. Nonsuppressible insulin-like activity (NSILA) from hunan serun: Recent accomplislments and their physiologic implications. Metab. 27:1803. Zobrisky, S.E., H.D. Naunann, A.J. Dyer and E.C. Anderspa. 1959. The relationship between the potassiun isotopes, K and meatiness of live hogs. J. Anim. Sci. 18:1480. Zweens, J., H. Grankens, A. Reicher and W.G. Zijlstra. 1980. Infrared-spectrometric determination of D20 in Biological fluids. Pflugers Arch. 385:71.