Relationship of Selected Beef Carcass Traits with Meat Palatability

Relationships among selected carcass traits and cooked meat palatability were studied on 240 carcasses obtained from steers of different biological types produced under a wide range of feeding regimens. Breed type of steer or feeding regimen had little or no effect on correlations among taste panel (TP) scores for tenderness, juiciness, flavor, and general acceptability. Treatments also had little effect on correlations of conformation, lean color, lean texture, and final maturity with TP observations. Late maturing breeds of steers and steers fed on low energy regimens were rated more youthful than early maturing breeds of steers and steers fed on high energy regimens. Marbling, percentage of longissimus muscle (LM) fat, quality grade, and adjusted fat thickness independently accounted for 2 to 3% of the variation in TP tenderness and 6 to 8% of the variation in TP acceptability

Sex, Age, and Breed Related Changes in Bovine Testosterone and Intramuscular Collagen

Castration of the male in meat-producing animals has long been a traditional practice in the production of commercial livestock. Numerous research studies have indicated that intact bovine males grow more rapidly, utilize feed more efficiently, and produce a higher yielding carcass than castrates. Even though young bulls have obvious growth and leanness advantages over steers, their meat is usually lower and more variable in tenderness than steers. These differences in tenderness have been attributed to differences in fatness or differences in connective tissue. Factors influencing the amount and strength of intramuscular collagen have been linked to animal age, sex, and breed. The literature strongly indicates that collagen solubility decreases significantly with animal age and that most of these changes take place from birth to about 2 years of age. Results have illustrated that the age-related changes in tenderness are significantly more pronounced in bulls than in steers and heifers, particularly in muscles high in collagen. These findings suggest that age-related changes in the cross-linking of collagen might be related to the sex of the animals. Several workers reported an increase in collagen content in young bulls at about 12 months of age. Others have suggested that the increase in collagen content at this age, which was accompanied by an increased solubility, was due to an increase in collagen synthesis related to the hormonal changes occurring during puberty in young bulls. The objective of this phase of our research was to investigate the influence of animal age, breed, and sex condition (bull vs steer) on the content and solubility of intramuscular collagen using muscle biopsies in the longissimus muscle

Factors Associated with Tenderness of Three Beef Muscles

Tenderness is the prominent quality determinant and probably the most important sensory characteristic of beef steak and roast meat. Currently postmortem aging (storage of carcass at refrigerated temperatures for 8 to 14 days) appears to be the best method for producing tender meat. Although the improvement in meat tenderness as a result of postmortem aging is measurable both subjectively and objectively, the exact mechanism responsible for this improvement in tenderness is unknown. It is well known that different muscles within the same carcass react differently to postmortem storage; for example, tenderloin is tender to begin with and does not improve significantly with postmortem storage, while ribeye is the toughest muscle initially and improves greatly with postmortem storage. The purpose of these experiments was to attempt to answer the following questions: 1)Why are some muscles (e.g., tenderloin) tender at 24 hr postmortem and nonresponsive to postmortem aging? and 2) Why do some muscles (e.g., ribeye and tenderloin) respond differently to postmortem aging

Factors Associated with Tenderness of Three Beef Muscles

Tenderness is the prominent quality determinant and probably the most important sensory characteristic of beef steak and roast meat. Currently postmortem aging (storage of carcass at refrigerated temperatures for 8 to 14 days) appears to be the best method for producing tender meat. Although the improvement in meat tenderness as a result of postmortem aging is measurable both subjectively and objectively, the exact mechanism responsible for this improvement in tenderness is unknown. It is well known that different muscles within the same carcass react differently to postmortem storage; for example, tenderloin is tender to begin with and does not improve significantly with postmortem storage, while ribeye is the toughest muscle initially and improves greatly with postmortem storage. The purpose of these experiments was to attempt to answer the following questions: 1)Why are some muscles (e.g., tenderloin) tender at 24 hr postmortem and nonresponsive to postmortem aging? and 2) Why do some muscles (e.g., ribeye and tenderloin) respond differently to postmortem aging

Elfazepam and Synovex-S Influences on Growth and Carcass Characteristics of Steers Fed Two Dietary Energy Levels

Synovex-S improves the average daily gain and carcass traits of steers and reduces losses under high feed price levels when compared to nonimplanted steers. High energy diets also influence average daily gain (ADG) favorably, but they increase the amount of fat and decrease the protein in carcass soft tissue in comparison to low energy diets

Microbial Decontamination and Weight of Carcass Beef as Affected by Automated Washing Pressure and Length of Time of Spray

Carcass beef has traditionally been washed by hand to remove foreign material such as hair, soil particles, and microbiological organisms that have contaminated the surfaces. These carcasses are inspected by the Food Safety Inspection Service (FSIS)to detect defects related to carcass cleanliness. Recent research and development of technology have emphasized automated machine washing. At pressures above that normally used, it is conceivable that water could penetrate tissue surfaces and be absorbed by the carcasses. Also, longer wash periods may enhance water uptake by carcasses. According to the ASH RAE Handbook and Product Directory, the average shrinkage of carcass beef using good current practices was 1.3% at 20 hr postmortem. USDA meat inspection regulations required that carcasses sustain no net increase in weight due to absorption of water during the washing process. There is no available literature on the effects of various automated washing techniques on carcass weights after a 20-hr chill. The objectives of the study reported presently were to determine the effects of nozzle pressure and length of time washed on the microflora and weights of carcass beef at 20 hr postmortem

Pharmacological Inhibition of mTOR and ERK1/2 Resulted in Attenuated Protein Synthesis Rates in Differentiated C2C12 Myoblasts in a Similar Fashion to in vivo Rodent Studies.

Fractional protein synthesis rates have long been used as in indicator of acute alterations in the anabolic state of various tissues. Through the use of a number of stable and isotopic tracer methodologies, the measurement of fractional synthesis rates (FSR) in vivo has become a staple of skeletal muscle physiology. Through the application of a deuterium oxide tracer, this project sought to measure pharmacological perturbations in fractional synthesis rates in culture in differentiated C2C12 murine myotubes. PURPOSE: To assess myofibrillar protein FSR in differentiated C2C12 murine myotubes following pharmacological inhibition of rapamycin-sensitive (mTOR) or -insensitive (ERK1/2) pathways, and how signal transduction through these pathways impact FSR as compared to previous in vivo studies of pharmacological inhibition studies in skeletal muscle. METHODS: C2C12 murine myoblasts were cultured in collagen coated 6 well culture dishes, and grown to 60-70% confluency using a high glucose DMEM growth media (GM). Cultures were transitioned to a differentiation media (DM) upon reaching target confluency. DM was changed daily for 4 days to allow for complete differentiation to myotubes. Cultures were randomly assigned treatment conditions of cell control (CC), rapamycin inhibition (RAPA), ERK1/2 inhibition (ERK), and electrical stimulation (ESTIM). Cultures underwent treatment conditions for 24 hours with a 4% deuterium oxide GM supplement. Analysis was carried out using a gas chromatography mass spectrometer. RESULTS: Fractional rates of protein synthesis were significantly lower in the RAPA (p=0.028) and ERK (p=0.029) groups as compared to CC, with no differences between RAPA and ERK groups (p\u3e0.05). Although statistics were not applied to the ESTIM group due to low sample size, electrical pulse stimulation shows promise for the stimulation of FSR in cultured myotubes. CONCLUSION: Diminished FSR in both RAPA and ERK groups are consistent with previous findings from in vivo rodent studies. These results may indicate comparable alterations in skeletal muscle anabolic signaling in cell culture as well as in vivo rodent models. Further investigations into anabolic signaling mechanisms related to the control of protein synthesis are needed

LIPOGENESIS IN ADIPOSE TISSUE FROM OVARIECTOMIZED AND INTACT HEIFERS IMMUNIZED AGAINST ESTRADIOL AND(OR) IMPLANTED WITH TRENBOLONE ACETATE

Forty-two heifers were allotted randomly to six treatment groups: 1) intact controls, 2) intact heifers implanted with trenbolone acetate, 3) ovariectomized heifers, 4) ovariectomized heifers implanted with trenbolone acetate, 5) intact heifers immunized against estradiol and 6) intact heifers immunized against estradiol and implanted with trenbolone acetate. Blood titers of estradiol-17β were increased over lO0-fold in heifers immunized against estradiol in Freund\u27s complete adjuvant or saline:squalene/arlacel containing Mycobacterium. Lipogenic enzyme activities and acetate incorporation into fatty acids were increased in subcutaneous adipose tissue obtained at slaughter from heifers receiving immunization or the combination of immunization and trenbolone acetate. The increased lipogenic capacity was not reflected in either cell diameter or cells per gram adipose tissue. Ovariectomy in combination with trenbolone acetate caused the lowest activities for all enzymes measured. This treatments also caused the greatest decrease in cell diameter, which resulted in the largest number of cells per gram of adipose tissue. Trenbotone acetate alone had no detectable effect on lipogenesis in the intact heifer, but the combination of ovariectomy and trenbolone acetate caused substantial decreases in enzyme activities, in most cases a significant decrease as compared with ovariectomized heifers. The data suggest that trenbolone acetate is able to depress lipogenesis only when not competing with the effects of circulating estradiol

LIPOGENESIS IN ADIPOSE TISSUE FROM OVARIECTOMIZED AND INTACT HEIFERS IMMUNIZED AGAINST ESTRADIOL AND(OR) IMPLANTED WITH TRENBOLONE ACETATE

Forty-two heifers were allotted randomly to six treatment groups: 1) intact controls, 2) intact heifers implanted with trenbolone acetate, 3) ovariectomized heifers, 4) ovariectomized heifers implanted with trenbolone acetate, 5) intact heifers immunized against estradiol and 6) intact heifers immunized against estradiol and implanted with trenbolone acetate. Blood titers of estradiol-17β were increased over lO0-fold in heifers immunized against estradiol in Freund\u27s complete adjuvant or saline:squalene/arlacel containing Mycobacterium. Lipogenic enzyme activities and acetate incorporation into fatty acids were increased in subcutaneous adipose tissue obtained at slaughter from heifers receiving immunization or the combination of immunization and trenbolone acetate. The increased lipogenic capacity was not reflected in either cell diameter or cells per gram adipose tissue. Ovariectomy in combination with trenbolone acetate caused the lowest activities for all enzymes measured. This treatments also caused the greatest decrease in cell diameter, which resulted in the largest number of cells per gram of adipose tissue. Trenbotone acetate alone had no detectable effect on lipogenesis in the intact heifer, but the combination of ovariectomy and trenbolone acetate caused substantial decreases in enzyme activities, in most cases a significant decrease as compared with ovariectomized heifers. The data suggest that trenbolone acetate is able to depress lipogenesis only when not competing with the effects of circulating estradiol

Comparisons of \u3ci\u3eBos indicus\u3c/i\u3e and \u3ci\u3eBos taurus\u3c/i\u3e Inheritance for Carcass Beef Characteristics and Meat Palatability

Crossbreeding is used widely to exploit heterosis and additive genetic variation among breeds to improve efficiency of beef production. The economic value of Bos indicus breeds of cattle, primarily Brahman, in crossbreeding programs in subtropical and tropical climates has been well established. In the temperate climatic conditions of U.S. Meat Animal Research Center, productivity of Bos indicus x Bos taurus F1 crossbred cows has been outstanding for reproduction an matemal performance relative to that of Bos taurus x Bos taurus F1 cross cows when mated to produce terminal-cross calves by Red Poll or Simmental sires. (Brahman and Sahiwal are Bos indicus [humped] breeds; Pinzgauer, Angus, Hereford, Red Poll and Simmental and other European breeds are Bos taurus [nonhumped] breeds)