|FRYLINCK, LORINDA - Agricultural Research Council Of South Africa|
|VAN WYK, G - Agricultural Research Council Of South Africa|
|Smith, Timothy - Tim|
|STRYDOM, P - Agricultural Research Council Of South Africa|
|VAN MARLE-KOSTER, E - Agricultural Research Council Of South Africa|
|WEBB, EDWARD - University Of Pretoria|
|SMITH, M - Agricultural Research Council Of South Africa|
Submitted to: Meat Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/24/2009
Publication Date: 9/21/2009
Citation: Frylinck, L., Van Wyk, G.L., Smith, T.P., Strydom, P.E., van Marle-Koster, E., Webb, E.C., Koohmaraie, M., Smith, M.F. 2009. Evaluation of Biochemical Parameters and Genetic Markers for Association with Meat Tenderness in South African Feedlot Cattle. Meat Science. 83:657-665.
Interpretive Summary: Meat quality is a significant issue for production beef cattle in South Africa (SA). Physiological and genetic parameters affecting meat quality, especially tenderness, were evaluated in major breeds used in SA feedlots. A major component of SA beef production uses Brahman (BrX), Simmental (SiX), and Nguni (NgX) crossbred cattle that have limited information regarding these parameters. The study examined the physical changes in postmortem muscle and some biochemical changes known to be associated with the degree of tenderness of the final product. Also, the final tenderness was directly measured, and the usefulness of DNA tests (for calpain and calpastatin) previously developed for improving tenderness was evaluated. It was determined that overall, meat tenderness of NgX animals tends to be dominated by problems with cold shortening during aging, probably related to the smaller size of the carcass of these animals. In the larger BrX and SiX animals, tenderness was still a problem despite apparent favorable biochemical profiles. Evaluation of the genetic markers suggests that neither calpain nor calpastatin markers in current use would provide substantial practical help in the SA production environment due to the relative frequency of favorable genetics in the breeds.
Technical Abstract: A large proportion of South African feedlot cattle are crossbreds of Brahman (BrX, Bos indicus), and Simmental (SiX, Bos taurus). A sample of 20 grain fed bulls from each of these crossbreeds was used to compare meat quality with that of the small frame indigenous Nguni (NgX, Sanga) by evaluating a variety of physiological and genetic parameters previously shown to be associated with meat tenderness. Shear force values were generally high (5.6 kg average at 14d post mortem), with SiX animals higher than BrX or NgX (P = 0.051) despite higher calpastatin:calpain ratio in BrX (P < 0.05). Calpain activity and cold shortening were both correlated with tenderness for all classes. The sample size was too small to accurately estimate genotypic effects of previously published markers in the CAST and CAPN1 genes, but the allele frequencies suggest that only modest progress would be possible in these South African crossbreds using these markers.