LAUSR

Abstract The objective of this study was to validate the effect of the SNPs rs210072660 and rs109221039 of the calpastatin (CAST) gene on meat toughness in Longissimus thoracis muscle aged for 1 d (±0; short-term ageing), 8 d (±1; medium-term ageing) and 15 d (±2; long-term ageing). The samples were obtained in experiments with different management strategies in Parda de Montana (grazing and concentrate-fed bulls, grazing steers, and steers finished on a total mixed ration) and Pirenaica (concentrate-fed bulls, steers and heifers, and steers on a total mixed ration) cattle. In the Parda de Montana breed, the Warner-Bratzler Shear Force (WBSF) was similar among management strategies under short-term aging, but it was lower for concentrate-fed bulls than for grazing bulls under medium-term and long-term aging (P   0.05) under short-term ageing, but the GG genotype had 14–16% greater WBSF than the GA and AA genotypes under medium-term ageing (P