Influence of preslaughter muscle temperature on muscle metabolism and meat quality in anesthetized pigs of different halothane genotypes.

Preslaughter muscle temperature in anesthetized pigs of different halothane genotypes (NN, Nn, and nn) was raised or lowered during a 45-min period of anesthesia. The different treatments produced muscle and rectal temperature differentials of 1.5 to 2 degrees C across genotypes. Blood and muscle biopsy samples were taken during the period of anesthesia, to study muscle energy metabolism by measuring different metabolites. After slaughter, the same metabolites and some meat quality characteristics were determined. An increased muscle temperature resulted in lower (P < .01) glycogen concentrations at slaughter and an increased (P < .05) glycogen, creatine phosphate, and ATP breakdown after slaughter in the muscles of these two halothane genotypes. However, the muscle metabolism of NN pigs was not affected by a higher temperature. The muscle metabolism of Nn pigs was more similar to that of NN pigs at low preslaughter temperatures. Elevated temperatures shifted the muscle metabolism of Nn pigs toward that of nn pigs. Water-holding capacity was lowered (P < .01) in all halothane genotypes due to elevated preslaughter muscle temperatures. It was concluded that increases in preslaughter muscle temperature are, in addition to an effect of preslaughter stress conditions, also a causative factor in enhancing ante- and postmortem muscle metabolism. This effect was more pronounced in Nn and nn pigs. Meat quality was influenced negatively in all genotypes by an increased muscle temperature, but more in NN and Nn pigs than in nn pigs. Lowering preslaughter muscle temperatures had the greatest advantage of improving meat quality in NN and Nn pigs.