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Ten attributes representing various body and. carcass measurements of beef steers were considered for statistical analysis. The slaughter data were obtained from an experiment conducted at Blacksburg, Virginia, by members of the Animal Science Department of the Virginia Polytechnic Institute, described by Kelly et al. (1968). The objective of the study was to obtain estimates of the effects of slaughter time (age), and of the energy level of the ration fed, on the body proportions and carcass composition of beef steers from approximately 7 to 30 months of age. The nutritional regimens used were: Ration I - maintenance; Ration II - full feed of hay; Ration III - limited concentrate plus full feed of hay; Ration IV - full feed of a fattening ration. According to the design of the experiment, the linear model included the general mean, the effects of slaughter time, breed, trial, slaughter time by trial interaction and slaughter time by breed interaction, and an error term. The first part of the investigation dealt with the analysis of variance of the percentage hot carcass to determine whether the effects of breed and trial were significant. In the second part, only the general mean, the slaughter time effect, and an error term were included in the model. When the slaughter time was found significant or highly significant, the sum of squares due to slaughter time was divided into regression components to determine which polynomial regression model best described the relationship between the body component mean and age. The results of the statistical analyses were as follows: 1. Breed and trial effects on the percentage hot carcass were insignificant in all but ration II, in which trial was significant. 2. Slaughter time by trial interaction effect was significant in all rations; slaughter time by breed was not. 3. The percentage hot carcass behaved in a parabolic manner with age, which was concave upward at lower planes of nutrition; the pattern changed to cubic at higher planes. 4. Age had no effect on the mean empty-body weight with steers on ration I; the effect was linear on ration II; quadratic on rations III and IV. Similar growth pattern was obtained for the percentage meat. 5. The percentage of front quarter to total carcass increased proportionately with age in all rations; the opposite trend was obtained for the percentage hind quarter. 6. The relationship of weight of the head, expressed as percentage of the live weight, with respect to age or slaughter time was linear with positive slope on rations I and II and negative on rations III and IV. 7. The percentage moisture in the meat showed a quartic regression with age on ration I presumably due to random fluctuation of the means. For rations II and III, the relationship was quadratic and concave downward; for ration IV, it was linear with negative slope. 8. The percentage crude protein and the percentage ash behaved similar to that of the percentage head, while opposite pattern was obtained for the ether extract. / Ph. D.

Under the conditions of this study, the following conclusions seemed justified: 1. Cud inoculations did not improve rate of growth or efficiency of feed utilization in calves through four months of age. Consumption of hay was not materially increased by cud inoculations. 2. Thus. it is concluded that cud inoculation is of no economic value under practical calf raising conditions. 3. Calves restricted in grain feeding did consume more hay than unrestricted calves; however, the increase was not great. Efficiency of feed utilization, as measured by the pounds of T. D. N. consumed per pound of gain was essentially the same for calves on a grain:hay ratio of 1:2 (restricted grain feeding) as those on a 1:1 grain:hay ratio (unrestricted grain feeding). 4. Skeletal growth, as determined by height at withers, was adversely affected by restriction or grain in the feeding program. 5. Calves fed one pound of whole milk per ten pounds of body weight daily up to 60 days of age, and a simple grain ration made satisfactory growth when grain was fed free choice (with a four-pound daily maximum) and hay of average or better quality was fed free choice. 6. Thus, it is indicated that a substantial monetary saving in the raising of herd replacements may be affected by the use of a simple grain ration instead of high-priced commercial calf mixtures. / Master of Science

A grazing trial was conducted to determine the relative value of three mixed-forage pastures, alfalfa-orchardgrass, bluegrass-white clover, and fescue-red clover. Three steers, three heifers and one esophageally cannulated steer were randomly assigned to each pasture treatment. Chemical composition, digestibility, voluntary intake, and selectivity of the forages were determined through use of esophageally cannulated steers and a rare earth marker (ytterbium). Forage intake appears to be most closely related to DM digestibility and content of the NDF and ADF fiber fractions. Some degree of forage selectivity was observed, although the specific species selected for and determinants of selectivity were not apparent. From the data obtained on levels of intake, digestibility and chemical composition, alfalfa-orchardgrass and bluegrass-white clover offer the highest quality forage of the three compared during the time of year studied. Fescue-red clover was consistently inferior in all respects. The digestible dry matter intake by cattle grazing alfalfa-orchardgrass, bluegrass-white clover and fescue-red clover was 3.2, 2.9 and 2.2 kg/d, respectively. More work needs to be done on a wider variety of pastures during different times of the grazing season. / Master of Science

Glucose pool size (PS), pool space (PV) and clearance rate (CR) vere determined for eight first-lactation Holstein cows at three lactation stages [early (E) = 75-100 days, late (L) = 205-250 days, and dry (D) ]. A corn silage-based ration (15% CP, 22% ADP) was fed ad libitum during lactation and at maintenance during D, using 4-hr feeding intervals. Three intravenous glucose (.1 g/kg BW) injections were administered each period. Serial blood samples were collected for 40 min post-dosing. Parameters were calculated by the least squares method using natural logarithms of glucose concentration. Basal plasma glucose and insulin concentrations were 57.4, 60.1, and 62.3 mg/dl and .78, .97, and 1.24 ng/ml, respectively, for E, L, and D, respectively. PS and PV increased (P<.05) from E to D; however, when adjusted for body weight there was no difference across stages. CR decreased (P<.05) from E (2.43%/min) to D (1.71%/min) and was correlated with dry matter intake (r = .70, P<.01). Glucose-induced insulin response was greater (P<.05) during D than during lactation due to higher peak (P<.05) and lover insulin clearance (P<.05) values. Glucose parameters were determined by single injection in lactating cows fed a high-concentrate ration (16.8% CP, 13% ADF) (n=5) and a control ration (16.3% CP, 24.4% ADF) (n=4) , at 90 and 120 days postpartum. No differences due to stage or diet were observed, due to insufficient observations. Plasma glucose and insulin tended to be higher with HC-feeding and at the later stage. / Master of Science

The effect of treatment with 3% aqueous ammonia and 5.3% urea plus jackbean meal on the nutritive value of wheat straw was investigated. The moisture content of the straw was raised to 40% by addition of water. Crude protein and in vitro dry matter digestibility were highest for the bottom layers, which had the highest moisture. The mean temperature during the first 4 wk post treatment was 11.2 C. Four diets were fed to sheep: untreated straw 1) alone or 2) with 20 g/d urea at feeding time 3) ammonia-treated straw, and 4) urea-treated straw. All diets contained 80 g of liquid molasses, 10 g of NaCl and 6 g of Na 2 S04, and were calculated to be isonitrogenous except the control diet (untreated straw without urea supplementation). Straw was chopped prior to feeding. Crude protein content in wheat straw was tripled by ammonia and urea treatment. Dry matter digestibility in vivo and in vitro was enhanced by ammonia and urea treatment, and the effect was higher for ammonia treatment. Digestibilities of cell wall constituents were higher (P<.05) for ammonia treated straw, compared to urea-treated straw. Urinary N excretion was considerably lower (P<.01) and N retention was higher (P<.01) for lambs fed treated straws, compared to those fed urea at feeding time. Ruminal NH3-N and blood urea concentrations were higher (P<.01) for the lambs fed urea at feeding time, compared to lambs fed the others diets. / M.S.

Diets of varying forage base were fed to dairy heifers to test the accuracy of an prediction equation to accurately predict dry matter intake (DMI). Heifers ranging from 120 to 430 kg body weight, were randomly assigned to treatments with forage bases of 1) 100% corn silage, 2) 75% corn silage : 25% alfalfa haylage, 3) 50 % corn silage : 50% alfalfa haylage, or 4) 25% corn silage : 75% alfalfa haylage. Diets were fed for an average of 187 days. Rations were formulated to meet NRC requirements for .68 kg ADG and reformulated monthly. Animals consistently gained an average of .8 kg per day. Statistical analysis showed actual DMI to be significantly less than predicted levels of DMI. The correlation coefficient of actual DMI to predicted DMI was .59. In spite of increased rates of gain, differences due to treatment, ration acid detergent fiber (ADF) and season were not significant. Depressed intake may be the result of metabolic control of intake as ADG approaches .8 kg. This suggests that current recommendations for TDN may be excessive for dairy heifers reared in confinement. / Master of Science

Two experiments with dairy cows during early lactation were conducted to determine the effects of feeding feather meal and fat. The objective of Experiment 1 was to determine milk production, milk composition, feed intake, and concentrations of AA and long chain fatty acids in blood plasma. Thirty two Holstein cows began a six week trial at the start of the fourth week of lactation. Diets included a control diet (51% forage, 49% concentrate, 16.8% CP, and 19.1% ADF) and diets containing 2.2% feather meal, 3.6% supplemental fat (hydrogenated tallow), or feather meal plus fat. Feather meal and supplemental fat were substituted for soybean meal and corn grain, respectively, in the control diet concentrate. For Experiment 2, four lactating Holstein cows (15, 20, 21, and 65 d postpartum) with ruminal and duodenal cannulae were used in a 4X4 Latin square design (21 d feeding periods) to determine digestibilities of the four diets. The markers used to estimate digesta flow were Co- EDTA and chromic oxide. When cows were fed feather meal, milk fat % was higher, milk protein % was lower, and plasma total essential AA were increased. Dry matter intake, milk production, and plasma long chain fatty acids increased when cows were fed diets containing fat. Differences between concentrations of AA in the tail artery and mammary vein indicated significant uptake by the mammary gland. The mammary gland extracted approximately 36% of the total essential AA in plasma. Intake, duodenal flow, and ruminal and total tract digestibilities of DM, ADF, N, and OM were similar for all diets. No changes were seen in rumen pH, rumen ammonia-N, VFA's, or rumen bacteria AA. Intake and fecal output of total, essential, and non-essential AA were greater when cows were fed diets containing feather meal. However, flow of AA to the duodenum, AA absorbed, and AA digestibilities did not differ. Results suggest that bypass proteins with a complimentary EAA profile must be fed with feather meal to compensate for the low amounts of Lys, Met, and His provided by feather meal. / Master of Science

The short-run interaction between the cattle feeding sector, as represented by <u>Cattle Fax</u> member feedlots, and the live cattle futures market is examined. The purpose of this research is to explore the simultaneity between placement decisions made in the cattle feeding sector and the price discovery process for distant contracts within the live cattle futures market. The efficiency of these processes will have implications to variability in supplies and thus, cash market prices for fed cattle. Input demand functions for feeder cattle were estimated as a function of numerous economic and technical factors. These modeling efforts reveal that cattle feeders consistently use distant futures prices in the formulation of expected prices when making placement decisions. Lead/lag analyses were conducted between the Cattle Fax placement series and the live cattle futures price series. Results from Granger type models reveal the live cattle futures market efficiently gathers and incorporates information on future supply conditions in the price discovery process for distant contracts. The recursive system created by these two models was examined and was found to be stable. The emergence of new information, pertinent to the feeding sector and the live cattle futures market, will cause orderly shifts to new equilibrium levels of placements of cattle on feed and distant live cattle futures prices. This research supports the conclusion that, because of the nature of the interaction between the live cattle futures market and the cattle feeding sector, the existence of the live cattle futures market aids in stabilizing the flow of cattle placed on feed. The results of stable flows of cattle placed on feed should be relatively stable flows of fed cattle marketings, and relatively more stable cash slaughter cattle prices. / Master of Science / incomplete_metadata

Series of blood samples were taken from Holstein calves before, and at 2, 4, and 6 hours after feeding. The blood plasma levels of tryptophane and methionine were determined by microbiological assay. It was found that the blood plasma levels of tryptophane and methionine varied considerably at different time intervals after feeding milk. One calf was fed 50 grams dl-methionine with its regular feed of milk, and series of blood samples were taken and assayed as in previous work. The methionine level increased to approximately 4 times its initial value by 2 hours after feeding, continued to rise, and at 6 hours after feeding was more than 10 times the original level. At the same time the tryptophane level showed a consistent decline. Determinations for total amino nitrogen were made, using a modification of the Folin-Wu method. The values obtained at different time intervals after feeding ranged from 6.45 to 9.33 mg./100 ml. blood. It was found that feeding methionine increased the blood level for total amino nitrogen, reaching a peak four hours after feeding. A special electrometric titration apparatus was used for making titrations. Approximately 1750 assays, consisting of standards and test samples, were titrated in this experiment. / M.S.