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item Riley, David
item Chase, Chadwick - Chad
item Hammond, Andrew - Andy
item WEST, R.
item JOHNSON, D.
item OLSON, T.
item Coleman, Samuel

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/20/2002
Publication Date: 2/12/2003
Citation: Riley, D.G., Chase, C.C., Hammond, A.C., West, R.L., Johnson, D.D., Olson, T.A., Coleman, S.W. 2003. Estimated genetic parameters for palatability traits of steaks from Brahman cattle. Journal of Animal Science. 81:54-60

Interpretive Summary: Brahman crossbred cattle are highly productive in the southern United States. However, they have the reputation of having less tender, lower quality beef as compared to other breeds. This reputation results in lower prices for calves that have any appearance of Brahman breeding. If bulls could be identified that have progeny that excel at tenderness traits, cow- -calf producers could address industry concern for tenderness yet continue to benefit from the superior performance of Brahman cross cattle. This project was designed to study the degree of genetic control over tenderness and palatability traits, including shear force (after 7, 14, and 21 days of aging), panel juiciness score, panel tenderness score, beef flavor intensity score, off flavor, connective tissue amount, percentage intramuscular fat (raw and cooked) and calpastatin (an enzyme responsible for limiting the extent and rate of tenderization associated with aging of meat) activity in straightbred Brahman cattle. We found that the genetic control over most of these traits was low to moderate. This means that sire selection programs would result in improvement of these traits at a slower rate than carcass or weight-type traits. Genetic control of the percentage of intramuscular fat was much higher. Effective implementation of these results could facilitate development of expected progeny differences (EPDs) for these traits. An effective tenderness improvement program in Brahman cattle should include identification of the best and worst sires with regards to tenderness, and should be complemented by usage of post-slaughter procedures such as electrical stimulation and aging.

Technical Abstract: Heritabilities and genetic and phenotypic correlations were estimated from carcass and beef palatability data collected from Brahman calves (n = 504) born in central Florida from 1996 to 2000. Traits evaluated included Warner-Bratzler shear force (after 7, 14, and 21 d of aging), panel tenderness score, connective tissue amount, juiciness, flavor intensity, and off flavor (after 14 d aging), percentages of raw and cooked lipids, and mg/g of muscle calpastatin activity. Parameters were estimated using an animal model and derivative free restricted maximum likelihood procedures. Estimated heritabilities for d 7, d 14, and d 21 shear force were 0.14, 0.14, and 0.06, respectively, indicating that improvement in these traits by selection would be slow. Estimated heritabilities of sensory panel attributes were 0.11, 0.12, 0.05, 0.04, and 0.01 for tenderness, connective tissue amount, juiciness, flavor intensity, and off flavor, respectively. The estimated heritabilities for percentages of raw and cooked lipids, and calpastatin activity were 0.34, 0.17, and 0.07, respectively. Genetic correlations among palatability traits were mostly of large magnitude and were consistent with other estimates from the literature. Genetic cor- relations of shear force or panel tenderness with fat thickness, marbling score, and with loin muscle area were generally low. These correlations seemed to indicate an opposite relationship (higher fat deposition with less tender EBVs) than many literature reports. Results indicated that tenderness improvement based upon selection for favorable shear force, sensory panel tenderness, or calpastatin activity would be slow. Selection against sires with the worst tenderness EBVs may be an effective alternative; postslaughter intervention programs should be also considered.