The primary objectives of this research were to characterize the involvement of lactate dehydrogenase (LDH) in color stability of physiologically different bovine muscles, and to investigate the influence of lactate enhancement on the myoglobin redox state of bovine muscles. In experiment 1, three different bovine muscles; Longissimus lumborum (LD), Semimembranosus (SM), Psoas major (PM) were (n=7 respectively) cut into steaks, and displayed for 7 days. Instrumental color, LDH-B, LDH isozyme expression, and NADH were measured. In experiment 2, strip steaks (n=8) were cut into half, and one side was injected with oxamate (LDH inhibitor), and the other was injected with water. Surface color, LDH, and NADH were measured after 10 days. In experiment 3, the three bovine muscles (n=10) were enhanced with solutions containing lactate and/or phosphate. Steaks were stored and displayed for 14 days. Instrumental color, LDH-B, total reducing activity (TRA), and NADH were measured. In experiment 4, fifteen beef strip loins were divided individually into four equal sections, and one of six treatments containing phosphate and/or calcium lactate with or without irradiation (2.4 kGy) randomly assigned to each loin section (n=10). Steaks were packaged in highoxygen modified atmosphere package, irradiated, stored in the dark at 1°C for 14 days. Instrumental color, TRA, lipid oxidation, and NADH were measured. LD remained the most red, whereas PM was most discolored. LD had a significantly higher level of LDH-1 responsible for LDH-B activity as compared to SM and PM. Consequently, LD had a higher LDH-B, and more NADH (p < 0.05). Inclusion of oxamate inhibited LDH-B, decreased NADH, and consequently discolored more. Potassium lactate enhancement led to more NADH through elevated LDH flux and subsequently increased (p < 0.05) color stability of LD and PM throughout display. Loins with calcium lactate/phosphate maintained the most stable red color during display. Calcium lactate/phosphate in loins increased NADH concentration, TRA, and were the least oxidized over display. These results confirm the involvement of LDH in meat color stability through replenishment of NADH. Lactate enhancement promotes meat color stability by providing superior antioxidant capacity and increased reducing activity of myoglobin by elevating NADH concentration.

The implementation of the Central America-Dominican Republic Free Trade Agreement (CAFTA-DR) has expanded trade opportunities for U.S. agricultural producers. U.S. beef is a critical product affected by the legislation, and the United States Meat Export Federation (USMEF) invested in a new product promotion program to increase exports of U.S. beef to Guatemala. The consumer responsiveness and effectiveness of the U.S. branded beef promotion program are analyzed in this study. Demand responses to promotion activities that launched three new U.S. beef value cuts in Guatemala’s Hotel, Restaurant and Institutional (HRI) sector were estimated by applying the Parks Model of Generalized Least Squares regression to pooled, time-series and cross sectional data. Results show a negative relationship between own price and sales quantity, while the effect of advertising on quantity sold is positive. Demand for the U.S. beef value cuts increased as a result of the promotion, although the costs of the promotion program exceeded the additional revenue generated as a result of promotion activities.

Two Texas fed beef and cow/bull packing plants were surveyed for high pH beef carcasses as well as the evaluation of functional properties of high pH beef in whole muscle beef jerky, frankfurters, and snack stick production. An estimated 42% of cow carcasses were of 6.0 muscle pH or greater as well as exhibiting darker, less red colored lean. Jerky high in pH from cow inside rounds resulted in the greatest percent moisture and least percent protein compared to other treatments. High pH cooked jerky were higher in (P < 0.05) pH and water activity and lower in percent fat and shear force values. In cooked jerky slices, fed-high resulted in the highest percent MPR and cook yield, but was the most tender. In contrast, fed-normal resulted in the least water activity, MPR and toughest jerky slices. In frankfurter production, emulsion stability and hydration values was highest for C (1.98mL) followed by 100H (3.37mL) that decreased as percent high pH decreased. As storage day increased, frankfurter pH decreased, especially by day 56 (5.67) where LAB and APC counts had reached a log of 6.0 indicative of spoilage by day 28 and became lighter and less red in color with minimal lipid oxidation. 100H was harder and less cohesive with trained panelists reported containing at least 50% high pH meat was harder. The pH and internal color of cooked snack sticks significantly increased and became lighter and redder as percent high pH meat increased. Even though water activity compared to a whole muscle dry product or an emulsified, water added product ranged from 0.85 to 0.86 (P > 0.05), minimal (P greater than 0.05) lipid oxidation occurred. 100N resulted in the least percentage of fat but 3% more (P less than 0.05) protein and highest shear force values. Overall, beef raw materials high in pH may be better suited in a semi-dry fermented product.

The objectives of this study were accomplished with two experiments in growing Bonsmara bulls (N = 68) (experiment 1), and Simmental crossbred calves (N = 132) (experiment 2). Specific objectives for experiment 1 were to characterize residual feed intake (RFI) in growing bulls, and examine relationships between RFI and performance, fertility, temperament and body composition traits. In experiment 2, the objectives were to examine stocker-phase supplementation effects on feedlot feed conversion ratio (FCR) and RFI and to characterize relationships between these feed efficiency traits, and performance and carcass traits in finishing calves. In both experiments, individual feed intakes and BW were measured. Ultrasound technology was used to measure body composition in experiment 1, while actual carcass measurements taken at harvest were used for experiment 2. Experiment 1 demonstrated that temperament affected ADG and DMI, but not FCR or RFI. Residual feed intake was not phenotypically correlated to scrotal circumference or bull fertility traits. Experiments 1 and 2 demonstrated that RFI was independent of ADG and BW, but that there was a tendency (P < 0.10) for RFI to be phenotypically correlated with 12th rib fat thickness (r = 0.20 and 0.22). However, RFI was not correlated with longissimus muscle area in either experiment. Both experiments demonstrated that low RFI (< 0.5 SD below mean RFI) calves consumed significantly (20 and 22%) less feed and had improved (21%) FCR compared to calves with high RFI (> 0.5 SD above mean RFI). Results from experiment 2 suggest that RFI measured while calves are consuming high-grain diets may be less influenced by previous level of stocker supplementation compared to FCR or residual gain efficiency traits. In summary, RFI was found to be phenotypically independent of growth rate and BW, had no effect on bull fertility or temperament traits, and was less impacted by previous plane of nutrition compared to FCR.

This study evaluated innovations in beef wholesale carcass fabrication that may have potential for improving subprimal yield and overall value of the beef carcass. Thirty beef carcasses, equally representing USDA Choice and Select and USDA yield grade 1 and 2, were selected from a commercial processing facility and transported to Texas A&M University for subsequent fabrication. Beef sides were utilized in comparing a conventional carcass fabrication style to a more innovative method. Innovative forequarter subprimal yields were greater (P < 0.001) for the brisket, ribeye roll, blade meat, and back ribs. The innovative method resulted in greater subprimal yield and less lean trim (P < 0.001) from the forequarter. Innovative hindquarter subprimal yields were greater (P < 0.001) for the tenderloin, top sirloin cap, bottom sirloin tri-tip, and round tip. Hindquarter subprimal yield and lean trim were not affected (P > 0.05). Value was greater for the innovative forequarter (P < 0.001) and hindquarter (P < 0.01); value was increased by more than seven dollars per beef side, thus greater than fourteen dollars per beef carcass. Selected subprimals were evaluated in a retail cutting test. Experienced retail professionals were utilized in fabricating the retail cuts. In general, the innovative retail subprimals performed equally or better than the conventional subprimals. The M. Serratus ventralis fabricated from the innovative side, comprising over 4.5% of the innovative forequarter, generated greater than 57% steak yield and 94% saleable yield. Innovative carcass fabrication techniques resulted in greater subprimal yield and increased the value of the entire beef carcass. These results were verified by retail cutting tests conducted on selected subprimals.

Purebred Beefmaster steers (n = 160) from five owners were fed at a commercial feedlot in South Texas beginning in November of 2004; 68 steers possessed pedigree information. Beginning in mid-November, steers were individually weighed and evaluated for ultrasound body composition at 56-d intervals by a certified technician. Feeder calf frame (FRM) and muscle (MUS) scores were assigned at initial ultrasound evaluation. Steers were fed and marketed through a lean-based, branded beef program and were harvested in two groups in May and June of 2005 at a commercial beef plant. Analyses were conducted to investigate the ability to predict carcass traits from the different sources of information available on these cattle. Evaluation of carcass traits were investigated using four sets of independent variables referred to as sources A, B, C, or D and ultrasound scan session (1 – 4). An analysis included initial weight at first scan session (IWT), FRM and MUS as independent variables through GLM procedures. B analyses utilized ultrasound measures of the longissimus area, intramuscular fat, fat thickness, rump fat, and gluteus medius depth along with IWT as independent variables. Multiple regression was performed on each carcass trait using IWT and ultrasound traits at each scan session. Mallow’s CP was used to select a model that best described each carcass trait. C analyses (GLM) utilized variables from A and B analyses combined plus ranch. D analyses (GLM) included variables from C analyses plus sire nested within ranch. Respective R-square values (scan 1 – 4) for marbling score were .02, .04, .05, and .10 using A information, .14, .17, .42, and .54, using B information, .35, .35, .47, and .55 using C information, and .56, .59, .65, and .76 using D information. R-square values ranged from .34 to .86 for carcass weight, .11 to .77 for fat thickness, .06 to .82 for ribeye area, and .10 to .81 for yield grade. Ultrasound data obtained closer to harvest and increasing amount of data related to genetic and management background showed increased R-square values, but may be best utilized in conjunction with one another to predict carcass traits and final carcass value.

Two experiments tested the efficacy of gonadotropin-releasing hormone (GnRH) or estradiol cypionate (ECP) administration in combination with controlled internal drug release (CIDR) inserts on pregnancy rate to fixed-time artificial insemination (FTAI) in beef heifers. In the first experiment, heifers in the two ECP groups received ECP in conjunction with the CIDR insert. The CIDR insert was removed and PGF was administered on either d 7 or 9. Heifers received ECP 24 h after CIDR removal and were inseminated 30 h after ECP. Heifers in the two GnRH groups received GnRH in conjunction with the CIDR insert. Heifers received PGF on either d 6 or 7, and the CIDR insert was removed on d 7. Heifers were inseminated and received GnRH 48 h after CIDR removal. Pregnancy rates to FTAI were higher for heifers treated with GnRH. Pregnancy rate to FTAI was highest for heifers in the GnRH group that received PGF on d 6 and was lowest for the group that received ECP in combination with a 7-d CIDR insert. In the second experiment, heifers received GnRH in conjunction with the CIDR insert. CIDR inserts were removed and PGF was administered on d 7. Heifers were inseminated 60 h later, with one group receiving GnRH at insemination. Pregnancy rate to FTAI was higher for heifers that received GnRH at insemination. The final experiment tested the efficacy of estradiol 17_ (E17) or GnRH in combination with a CIDR insert on pregnancy rate to FTAI in Brahman cows. Either E17 or GnRH was administered in conjunction with the CIDR insert. CIDR inserts were removed on d 7. Cows in the GnRH group received PGF on d 6 and GnRH at insemination which occurred 48 h after CIDR removal. Cows in the E17 group received PGF on d 7, E17 24 h later, and were inseminated 30 h after E17 administration. Pregnancy rate to FTAI was higher for cows treated with E17. These data indicate acceptable pregnancy rates were obtained when the CIDR insert was combined with either GnRH in beef heifers or with E17 in Brahman cows.

Thesis (M.S.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains viii, 52 p. : ill. Vita. Includes abstract. Includes bibliographical references (p. 36-39).

Thesis (Ph. D.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains vi, 123 p. Includes abstract. Includes bibliographical references.

Thesis (Ph. D.)--University of Missouri-Columbia, 2003. / Typescript. Vita. Includes bibliographical references (leaves 162-201). Also available on the Internet.