β-alanine or L-carnosine prevents the development of pale, soft and exudative pork by inhibiting the glycolysis of porcine longissimus dorsi muscle

Carnosine plays an important role in regulating muscle buffering capacity and glycolysis. In order to investigate the effects of dietary {beta}-alanine, L-histidine, and L-carnosine supplementation on the pH value, glycolytic potential, the activities of AMP-activated protein kinase (AMPK) and pyruvate kinase (PK) activities in the porcine longissimus dorsi muscle, a total of 60 barrows with an average body weight (BW) of 50.5 {+/-} 1.7 kg were assigned into five groups which received diets containing basal diet (control, CON), 0.04% {beta}-alanine ({beta}-ALA), 0.06% L-histidine (L-HIS), 0.04% {beta}-alanine+0.06% L-histidine ({beta}-ALA+L-HIS), or 0.1% L-carnosine (L-CAR). The results showed that dietary supplementation of the combination of {beta}-ALA and L-HIS or L-CAR significantly increased (P < 0.05) the average daily gain (ADG) of pigs with 50-75 kg BW, compared with other three groups. Compared with L-CAR group, L-HIS supplementation significantly decreased (P < 0.05) the average daily feed intake (ADFI) of pigs. There were no significant difference (P > 0.05) in back fat thickness and loin eye area among treatments. At 0, 1 and 24 h postmortem (PM) the pH values in the longissimus dorsi muscle (LM) of pigs receiving L-CAR were higher (P < 0.05) than that of pigs receiving CON diet. The redness (a*) values of LM of pigs in the {beta}-ALA+L-HIS or L-CAR group were higher (P < 0.05) than those in other three groups. The glycolytic potential of LM was not significantly different (P > 0.05) among treatments. At 1, 24 h PM the AMPK activities in LM of pigs receiving {beta}-ALA, {beta}-ALA+L-HIS and L-CAR were much lower (P < 0.05) than those of pigs receiving CON diet or L-HIS. 0.1% L-carnosine or 0.04% {beta}-alanine supplemented to pigs diet was effective in regulating AMPK and PK activities in the porcine longissimus dorsi muscle and preventing the development of pale, soft and exudative (PSE) pork.