Three (intact) Angus males and three females which were half-sibs and born within 21 days of each other were selected for this study. Each animal was bled and biopsied periodically from suckling calves to mature slaughter weights, to determine the qualitative composition of lipoproteins and to differentiate the lactate lipogenic activity of subcutaneous tissue during growth and development. At slaughtered, a sample of intramuscular adipose tissue was taken to determine the lactate lipogenic activity at this location. Two days later, one side of each carcass was separated into wholesale cuts. Each wholesale cut was dissected into separable bone and soft tissue and sampled for protein, lipid and moisture determinations. The elution profiles of lipoproteins were similar for all animals. Major peaks observed were (1) very low density (VLDL), (2) low density (LDL) and (3) high density lipoproteins (HDL). Triglycerides, cholesterol and protein were not significant (P < .05) between males and females for the VLDL. At one year of age, females had large (P < .05) amounts of protein for the HDL. In both groups of cattle, largest (P > .05) amounts of protein were greater in the HDL at 9 months of age. Profiles of HDL apoproteins at all ages showed that in both groups of cattle, a distinct band with a weight of about 28,000 was present representing apo-AI. Apo-protein components of pooled LDL fractions showed a protein which was unable to enter the acrylamide gel (7.5 – 20%) used. The component may represent apo-B with a molecular weight of about 250,000. The lactate lipogenic activity of subcutaneous adipose tissue was larger in the males and only significant (P < .05) at 9 months of age. The lipogenic activity was higher (P > .05) in the subcutaneous tissue when compared to the intramuscular tissue at slaughter. In both cases, males showed to use more (P > .05) lactate for fatty acid synthesis in intramuscular and subcutaneous tissue than the females. Magnitude of quality and yield for carcass traits were better for the males than females. Bone, meat and lean weights were significantly (P < .05) greater for the males, however, on a percentage basis per side weight, differences were eliminated. In addition, no significant (P > .05) effect was present between male and female wholesale and side carcass composition.

Revised; Originally Published: 2000 / 8 pp.

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Master of Science / Department of Animal Sciences and Industry / Terry A. Houser / The objective of this study was to determine the effect of extended postmortem aging (DOA), steak location (LOC), and dietary treatment (TRT) on cooked meat tenderness, sarcomere length, and myofibrillar protein degradation of steaks from the Semitendinosus (ST) and Longissimus lumborum (LL). Crossbred feedlot steers (n = 40; initial body weight 638 ± 29 kg) were fed 45 d with the following diets: a control diet, control diet with microalgae meal, microalgae meal and antioxidants fed at the beginning of feeding, and microalgae meal with antioxidants fed during the final 10 d of feeding. The ST and LL were removed from carcasses. The ST was fabricated into 10 steaks, which were paired with an adjacent steak and assigned 5 LOC; LOC 1 was the most proximal and LOC 5 was the most distal. Each LOC was randomly assigned an aging period of 7, 14, 28, 56 or 112 d. The 6 most posterior steaks of the LL were paired with an adjacent steak and assigned 3 locations; LOC 1 being the most anterior and LOC 3 the most posterior. Each LOC of the LL was randomly assigned an aging period of 7, 28, or 112 d. Shear force, sarcomere length, muscle fiber type and size, postmortem proteolysis, and calpain activity were measured across aging periods for each LOC. Improved Warner-Bratzler shear force (WBSF) values were detected throughout the 112 d aging period for both ST and LL steaks (quadratic; P < 0.01). The largest decrease in shear force occurred between d 7 and 28 for LL and ST steaks. Shear force decreased (P < 0.01) from LOC 1 to LOC 5 (proximal to distal) in ST steaks. Steak LOC 5 had the longest sarcomeres over LOC 1, 2, and 3 on d 7, 14, and 28 (P < 0.01) in the ST; LOC 4 and 5 also had a greater percentage of Type I fibers (P < 0.01). Muscle fiber size in ST steaks decreased (P = 0.01) from LOC 1 to LOC 5. As DOA increased, intact calpain-1 decreased (quadratic; P < 0.01), with intact calpain-1 completely disappearing by d 56 and d 28 in the ST and LL, respectively. Intact desmin and troponin-T decreased throughout the 112 d in ST and LL steaks (linear; P ≤ 0.03). Degraded desmin-38 kDa increased (P < 0.01) between d 14 and d 28; however, degraded desmin-38 kDa did not continue to degrade (P = 0.76) from d 56 to d 112 in ST steaks. Degraded desmin-35 kDa content, however, continued to increase through d 112 (P < 0.01). Muscle fiber size and type along with sarcomere length played a substantial role in tenderness differences in steak LOC, whereas calpain and proteolytic activity played a substantial role across DOA.

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Call number: LD2668 .T4 1952 F3 / Master of Science

Master of Science / Department of Animal Sciences and Industry / Michael D. MacNeil / Jennifer M. Bormann / Genetic and phenotypic data are often provided to bull buyers at time of sale to aid producers in establishing economic value (pricing) of candidates for selection. This study evaluates the association between the information provided to bull buyers at time of sale and prices paid for bulls sold by two large seedstock operations located in Kansas (KS Ranch) and Colorado (CO Ranch). Data were gathered from 15 sale catalogs that documented bulls sold at auctions taking place from 2009 to 2013. In total, there were 39 potential predictor variables recorded for 2,601 Angus bulls for the KS Ranch; while 14 plausible predictor variables were recorded for 504 purebred and 1,399 Stabilizer bulls at the CO Ranch. Due to extensive multicollinearity between predictors, principal component (PC) analyses were conducted on the standardized predictors to reduce dimensionality within each ranch and genetic group. Eleven PC were considered to provide important meaningful information in summarizing the 39 predictors originally available to buyers at the KS Ranch. For both the purebred and Stabilizer bulls from each set of breed type data in the CO ranch, 6 principal components had eigenvalues greater than 1.0. Similar to the findings for the KS Ranch, these PCs also explained approximately 75% of the cumulative variability of the predictors. Sale prices were then regressed on the corresponding PC using a stepwise selection to identify the PC subset that most significantly explained the behavior of bull sale prices (P < 0.05). The final models explained approximately 63%, 37% and 58% of the variation in sale prices received for Angus, purebred and Stabilizer bulls, respectively. Interpretation of the eigenvectors for the PC having the greatest eigenvalues led to the conclusion that buyers put the most weight on growth traits followed by carcass characteristics and economic selection indices. However, no distinction of a specific variable’s numerical impact on price was determined.

No description available.