title: 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 120min and 24h 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 45min, and 24h postmortem. HAL mutants, compared with HAL normal, had lower (P<0.05) ATP concentrations at 0 and 30min, lower (P<0.05) pH at 45min, and hastened glycogen degradation and lactate accumulation in the first 120min postmortem (HAL×time, P<0.0001). RN mutants had greater (P<0.0001) glycolytic potentials than RN normal, and lower (P<0.05) 24h 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 0min. Compared with HAL normal, HAL mutants had elevated (P<0.05) muscle glucose concentrations at 30, 60, and 120min, and 24h. RN mutants had higher (P<0.05) glucose levels than RN normal after 60min. 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 30min. From 60min to 24h 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.
authors: Department of Animal Sciences, Purdue University, Room 202A, 1151 Smith Hall, West Lafayette, IN 47907-1151, USA.
authors: T L
authors: TL
authors: Copenhafer
authors: B T
authors: BT
authors: Richert
authors: A P
authors: AP
authors: Schinckel
authors: A L
authors: AL
authors: Grant
authors: D E
authors: DE
authors: Gerrard