The calpain-calpastatin system (CCS) comprises a family of calcium-dependent neutral proteases, the calpains, and calpastatin, a specific inhibitor of the calpains that regulates their activity in vivo. The CCS is found in most animal tissues and influences many important processes including muscle development and degeneration, meat tenderisation postmortem, cataract formation and fertility. The calpains have been shown to play the major role in postmortem tenderisation in beef, lamb and pork by degrading specific muscle structural proteins. The level of calpastatin immediately postmortem appears critical in determining the ultimate tenderness of aging muscles. Tenderness has been shown in consumer surveys and tasting panel tests to be the most important characteristic determining the overall eating quality of meat. In using a molecular genetic approach to studying meat quality in sheep we have chosen the ovine calpastatin gene (CAST) as a candidate gene for meat quality. We have described a three allele system of polymorphic variants (CAST a, b and c) in a region of the ovine CAST. Since 1995 we have carried out slaughter trials on small groups of Dorset Down hoggets and Dorset Down x Coopworth lambs to ascertain any association between meat quality traits and the molecular markers in CAST. Sheep with the genotypes of CAST aa, ab and ac were compared. These trials indicate an association of the CAST genotype ac with increased liveweight gain (+12-17%,p >0.05), increased age-corrected carcass weight (+15-18%, p>0.05), but also increased longissimus dorsi shear force (+4-12%, nonsignificant) compared to sheep with the CAST genotype aa.
Proceedings of the New Zealand Society of Animal Production, Volume 59, , 266-268, 1999
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