Abstract
This study investigated the attenuating effects of dietary creatine nitrate (CrN), a novel form of creatine, on energy expenditure and rapid glycolysis in pectoralis major (PM) muscle of broiler induced by preslaughter transport. A total of 288 Arbor Acres broilers (28 day old) were randomly assigned into five dietary treatments, including a basal diet or the basal diet supplemented with 600 mg/kg guanidinoacetic acid (GAA), 300, 600, or 900 mg/kg CrN for 14 d, respectively. On the day of transportation, the broilers from basal diet group were divided into two equal groups: one group was transported for 0.5 h (Control group) and the other group was transported for 3 h (T3h group). Meanwhile, the birds from GAA and CrN supplementation groups were transported for 3 h (identified as GAA600, CrN300, CrN600, and CrN900 group, respectively). The results demonstrated that dietary supplementation of GAA or CrN from 28 to 42 d of age did not significantly affect the growth performance, carcass traits, and textural characteristics (P > 0.05) in PM muscle of transported broilers. Compared with T3h group, GAA600, CrN600, and CrN900 groups increased the pH45min (P < 0.01), and CrN600, CrN900 groups decreased the cooking loss (P < 0.05) of PM muscle. Meanwhile, the muscle of GAA600, CrN600, and CrN900 groups showed a higher glycogen content (P < 0.01) and a lower lactic acid content (P < 0.01). GAA600 and all CrN treatments enhanced muscle Cr content and reduced AMP/ATP ratio (P < 0.01). In addition, GAA600 and all CrN treatments downregulated the relative mRNA expression levels of LKB1 and AMPKα2 (P < 0.001) and the protein expression of p-AMPKαThr172 compared with the T3h group (P < 0.01). All CrN treatments showed lower protein expression levels of LKB1 and p-LKB1Thr189 than those of the T3h group (P < 0.05). In summary, dietary supplementation with GAA and CrN enhanced the content of muscle creatine, and inhibited transport-induced activation of LKB1/AMPK pathway, which is beneficial for delaying rapid muscle glycolysis and improving meat quality.