Augmented postmortem glycolysis does not occur early postmortem in AMPKγ3-mutated porcine muscle of halothane positive pigs

Abstract

The objective of this study was to determine the effects of the halothane (HAL) and Rendement Napole (RN) genes on the rate-limiting reactions of glycolysis and their relationship to pork quality development. Samples were collected from the longissimus muscle at 0, 30, 60, and 120 min and 24 h postmortem from homozygous HAL and RN pigs (NN/rn +rn +, NN/RN −RN −, nn/rn +rn +, nn/RN −RN −). Muscle pH was recorded at 0, 15, and 45 min, and 24 h postmortem. HAL mutants, compared with HAL normal, had lower ( P < 0.05) ATP concentrations at 0 and 30 min, lower ( P < 0.05) pH at 45 min, and hastened glycogen degradation and lactate accumulation in the first 120 min postmortem (HAL × time, P < 0.0001). RN mutants had greater ( P < 0.0001) glycolytic potentials than RN normal, and lower ( P < 0.05) 24 h pH compared with the normal genotype, but not the HAL mutant genotype. The HAL mutation negatively affected ( P < 0.05) L∗, b∗ and color scores whereas both HAL and RN mutations independently decreased ( P < 0.05) firmness, marbling and water holding capacity. RN mutant genotypes had higher ( P < 0.0001) phosphocreatine concentrations than other genotypes at 0 min. Compared with HAL normal, HAL mutants had elevated ( P < 0.05) muscle glucose concentrations at 30, 60, and 120 min, and 24 h. RN mutants had higher ( P < 0.05) glucose levels than RN normal after 60 min. Glucose-6-phosphate (G6P) concentrations decreased ( P < 0.05) during the first hour postmortem except in HAL/RN mutants, which had higher ( P < 0.01) G6P concentrations than all other genotypes at 30 min. From 60 min to 24 h postmortem, G6P increased ( P < 0.05) in HAL normal genotypes. Altogether, these data show that elevated muscle glycogen content does not further aggravate rapid early postmortem metabolism.