Tenderness of normal and callipyge lamb aged fresh or after freezing

The present experiments were conducted to determine if tenderness differed between normal (N) and callipyge (CLPG) lamb during post-mortem aging of: (1) longissimus muscle (LM), (2) semimembranosus muscle (SM), and (3) LM after freezing for 6 weeks. In the LM, CLPG chops were tougher ( p < 0.01) than N at every post-mortem age and after 24 h CaCl 2 marination of a day 1 chop. Post-mortem aging reduced ( p < 0.05) shear force of the LM in both N and CLPG; however, this reduction proceeded at a slower rate (−0.127 vs −0.341 kg d −1; p = 0.01) and for a longer time period (24 vs 6 days; p < 0.05) in CLPG than N. In the SM muscle, shear force values did not differ ( p > 0.05). due to phenotype, post-mortem age, or the two-way interaction. Freezing prior to aging accelerated the rate of post-mortem tenderization in CLPG (−0.130 vs −0.060 kg d −1; p = 0.004) while no changes ( p > 0.05) were observed for N. Phenotypic expression of the CLPG gene increased the toughness of the LM with no change in SM; however, freezing prior to aging accelerated the post-mortem tenderization process in CLPG LM.