Corticosterone alters meat quality by changing pre-and postslaughter muscle metabolism

Two experiments were conducted to investigate the effect of acute preslaughter stress mimicked by exogenous corticosterone (CORT) administration on postmortem muscle metabolism of broiler chickens. Altered protein metabolism, glycogen depletion, and meat quality characteristics were investigated in the musculus pectoralis major (PM) and musculus biceps femoris of broiler chickens. Results showed that CORT administration resulted in increased proteolysis and gluconeogenesis, whereas the capacity for protein synthesis was not obviously changed. Plasma levels of glucose, urate, and total free amino acids were all significantly decreased by CORT treatment. The effect of CORT administration on muscle R-values remained uncertain. The initial muscle buffer capacity was increased by CORT treatment in both musculus pectoralis major and musculus biceps femoris. The results suggested that the acute premortem up-regulation of CORT decreased muscle ultimate pH by increasing the antemortem muscle glycogen content and its depletion rate postmortem, which in turn induced a decrease in water-holding capacity. Muscle buffering capacity might be altered by CORT administration, and its involvement in the change of muscle pH needs to be investigated further.