Activities of metabolic and contractile enzymes in 18 bovine muscles.

Contractile and metabolic characteristics of 18 bovine muscles were studied using 10 animals of various ages (2-10 years), sexes (females, males and castrated males) and types (dairy, meat or crossbred). Contractile type was assessed by measuring myofibrillar Ca-Mg-activated ATPase activity. Metabolic type was appraised by determining phosphorylase, glycogen synthetase, hexokinase, haem iron as well as glycolytic and mitochondrial oxidative activities. 'Glycolytic potential' and buffer capacity (as change in lactate concentration as a function of change in pH) were measured. The results showed that myofibrillar ATPase activity was positively related to glycolytic activities and negatively related to oxidative activities. Ultimate pH was negatively correlated with myofibrillar ATPase activity and had little if any relationship to the glycolytic potential. Metabolic and contractile activities were essentially unaffected by sex, age or breed type.