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Title: PREDICTION OF BREEDING VALUES FOR TENDERNESS OF MARKET ANIMALS FROM MEASUREMENTS ON BULLS

Author
item BARKHOUSE, KRISTEN
item Van Vleck, Lloyd
item Cundiff, Larry
item Koohmaraie, Mohammad
item Lunstra, Donald
item Crouse, John

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/29/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: A problem in selection for meat tenderness is that measurements are taken on dead animals. Thus, the animal with known tender meat is not available for reproduction. Progeny tests can be done but extend the generation interval and would be very expensive. An alternative explored in this study is to obtain semen of bulls for freezing before slaughter and to select semen to use based on tenderness of the slaughtered bull. Effect- iveness of such selection also requires that tenderness measured on bulls represents tenderness measured on their market progeny -- steers and heifers, i.e., the genetic correlation between expression of the same genes for tenderness in bulls and market animals should be large. This study, based on 237 bulls and 1431 related market animals, found such favorable genetic correlations for various measurements of tenderness. The estimate of heritability in market animals for shear force was low, .02. If, however, the literature estimate of .27 is assumed, then in improving market animal tenderness by selection of bulls based on tenderness measured after pre-slaughter semen collection should be relatively effective.

Technical Abstract: Data were tenderness measures on steaks from 237 bulls (Group II) slaughtered after producing freezable semen and on 1,431 related steers and heifers (market animals, Group I) from Angus, Hereford, Pinzgauer, Brahman, and Sahiwal crosses from the Germ Plasm Evaluation Project at the U.S. Meat Animal Research Center. Tenderness was assessed through Warner-Bratzler Shear Force (SF), taste panel tenderness (T), marbling score (MS), and myofibrillar fragmentation index (MFI). For all traits, as fraction Bos indicus inheritance increased, implied tenderness decreased. Heritability estiamtes were generally not significantly different from zero. Genetic correlations generally indicated favorable association among the traits. The range in predicted breeding values of bulls for market animal tender- ness was small and from -.34 to .32 kg for market animal shear force. Because of somewhat lower than expected estimates of heritability for SF or rT, results from this experiment indicate that selection based on tendernes of steaks sampled from intact or late castrate males slaughtered following collection of freezable quality semen would not be very effective in improving tenderness of steaks from steers or heifer progeny. If a mean of heritability estimates reported in the literature of .27 for shear value were assumed for market steer and heifer progeny instead of .02 found in the present study, then selection for estimates of shear force in young bulls (heritability of .27) would be relatively effective in improving shear force of market progeny.