Resistance to pH decline and slower calpain-1 autolysis are associated with higher energy availability early postmortem in Bos taurus indicus cattle.

Beef from Bos taurus indicus is associated with toughness compared to Bos taurus taurus, suggesting there is antagonism between adaptability to heat and beef quality. Resistance to cellular stress in muscle may be protective postmortem, thereby delaying its conversion to meat. Therefore, our objective was to determine pH decline, calpain-1 and caspase 3 activation, and proteolysis in different biological cattle types. Angus, Brangus, and Brahman steers (n = 18) were harvested, and Longissimus lumborum were assessed postmortem for pH decline, ATP content, protease activation, and calpastatin content; and myofibrillar protein degradation was evaluated in beef aged to 14d. Brahman Longissimus lumborum exhibited resistance to pH decline, greater ATP content at 1 h, and delayed calpain-1 autolysis. Although content of caspase-3 zymogen was lower in Brahman, there was no evidence of caspase-3 mediated proteolysis. Greater resistance to energetic and pH changes early postmortem in Brahman Longissimus lumborum are associated with calpain-1 autolysis but not mitochondria mediated apoptosis.