No abstract

This study aimed to evaluate the effects of dietary creatine nitrate ( CrN ) on growth performance, meat quality, energy status, glycolysis, and related gene expression of liver kinase B1/AMP-activated protein kinase ( LKB1/AMPK ) pathway in Pectoralis major ( PM ) muscle of broilers. A total of 240 male Arbor Acres broilers (28-day-old) were randomly allocated to one of 5 dietary treatments: the basal diet (control group), and the basal diets supplemented with 600 mg/kg guanidinoacetic acid ( GAA ), 300, 600, or 900 mg/kg CrN (identified as GAA 600 , CrN 300 , CrN 600 , or CrN 900 , respectively). We found that dietary GAA and CrN supplementation for 14 d from d 28 to 42 did not affect broiler growth performance, carcass traits, and textural characteristics of breast muscle. GAA 600 , CrN 600 , and CrN 900 treatments increased pH 24h and decreased drip loss of PM muscle compared with the control ( P < 0.05). The PM muscles of CrN 600 and CrN 900 groups showed higher glycogen concentration and lower lactic acid concentration accompanied by lower activities of phosphofructokinase ( PFK ), pyruvate kinase ( PK ), and lactate dehydrogenase ( LDH ) ( P < 0.05). Simultaneously, GAA 600 and all CrN treatments increased concentration of muscle creatine, phosphocreatine ( PCr ) and ATP, and decreased AMP concentration and AMP/ATP ratio ( P < 0.05). Meanwhile, the concentrations of muscle creatine, PCr, and ATP were increased linearly, while muscle AMP concentration and AMP/ATP ratio were decreased linearly and quadratic as the dose of CrN increased ( P < 0.05). GAA 600 , CrN 600 , and CrN 900 treatments upregulated mRNA expression of CreaT in PM muscle, and CrN 600 and CrN 900 treatments downregulated GAMT expression in liver and PM muscle compared with the control or GAA 600 groups ( P < 0.05). The mRNA expression of muscle LKB1, AMPKα1 , and AMPKα2 was downregulated linearly in response to the increasing CrN level ( P < 0.05). Overall, CrN showed better efficacy on strengthening muscle energy status and improve meat quality than GAA at the some dose. These results indicate that CrN may be a potential replacement for GAA as a new creatine supplement.