Submitted to: Florida Beef Cattle Short Course
Publication Type: Proceedings
Publication Acceptance Date: May 2, 2007
Publication Date: May 2, 2007
Citation: Riley, D.G., Chase, C.C., Johnson, D.D., Olson, T.A., West, R.L., Coleman, S.W., Phillips, W.A., Franke, D.E., Casas, E. 2007. Utilization of Bos Indicus cattle in Florida beef enterprises: Carcass Traits and Merit. Florida Beef Cattle Short Course Proceedings; "Enhancing Quality Production While Maintaining Profitability". Pages 47-80.
The F1 Brahman cow is the most productive cow type for the Southern United States, both in terms of reproduction (calving and weaning rate) and maternal ability. However, the substandard quality and tenderness of beef from Brahman and Brahman-cross cattle is an opportunity for improvement in the breed. The objective was to examine and discuss the genetic opportunities for improvement of carcass traits in Brahman. Selection is one potential genetic improvement program. Results from a seven-year sire progeny test showed that estimates of heritability were moderate to high for most beef traits in purebred Brahman (greater than 0.35), therefore, genetic improvement appears to be quite feasible with rapid trait improvement. Traits related to tenderness, such as Warner-Bratzler shear force or sensory panel assessment of tenderness had lower heritabilities (less than 0.2); improvement of these traits would likely be more efficient using a combination of selection and other tenderness management programs, such as electrical stimulation. Three aspects of physical tenderness were considered to construct curves representing tenderness values across time: 1) tenderness at the beginning of the aging period, 2) tenderness at the end of the aging period, and 3) the rate of change. Sires appeared to differ greatly in how steaks from their progeny fit into these three aspects; these sire differences may be indicative of genetic control of tenderness improvement associated with aging. A subset of the Brahman sire progeny test was used to compare the influence of many different carcass traits on tenderness; collagen content (connective tissue) of Brahman steaks was the most important variable that influences multiple aspects of tenderness after different aging times. Knowledge of the genetic control of collagen content in Brahman populations may be useful when designing selection programs for improvement of tenderness. Early results from molecular genetic studies indicate that there are two genes with different alleles that appear to explain some of the tenderness (Warner-Braztler shear force) differences in purebred Brahman cattle, and it may be possible to use these results to identify parents that can produce progeny with steaks that are relatively more tender. It is mostly unknown how strong selection of parents for product tenderness (or many other carcass traits) will affect other production traits in Brahman cattle. The high value of the Brahman breed is to produce crossbred cows that excel in both reproductive and maternal abilities. Any selection program for improvement of carcass traits must not compromise or sacrifice excellence in those areas.