188 Effects of dietary supplementation of L-histidine and beta-alanine on growth performance breast muscle carnosine content and carnosine-related enzyme mRNA expression in broiler chicks.

摘要

The current study was performed to investigate effects of dietary addition of L-histidine and β-alanine on growth performance, breast carnosine content and carnosine-related enzyme mRNA expression in broiler chicks. A total of 640 1-day-old male broiler chicks were assigned into 8 treatments with factorial arrangement containing 4 level of L-histidine supplementation (0, 650, 1300 or 1950 mg/kg) and 2 levels of β-alanine (0 or 1200 mg/kg). Each treatments consisted of 8 replicates with 10 birds each. The results showed that dietary L- histidine, β-alanine and their interaction did not affect the growth performance. Interaction between histidine and β-alanine existed on meat color. Dietary supplementation of 1950 mg/kg L-histidine resulted in higher a* value, and 1300 mg/kg histidine+1200 mg/kg β-alanine had the lowest b* value. Dietary L-histidine at 1300 or 1950 mg/kg level had higher pH compared with the exogenous L-histidine free control. In breast muscle, both dietary L-histidine and β-alanine elevated the total antioxidant capacity and glutathione peroxidase activity and decreased malondialdehyde content, and dietary histidine additionally increased the total superoxide dismutase activity. The combination of 1300 mg/kg L-histidine and 1200 mg/kg β-alanine had the superior muscle antioxidant ability. Muscle carnosine contents were increased by L-histidine, β-alanine and their interaction. The group of 1300 mg/kg L-histidine plus 1200 mg/kg β-alanine had the highest carnosine and anserine content in breast muscle. Both L-histidine and β-alanine supplementation significantly elevated carnosine synthase mRNA expression, and L-histidine further increased the expression of transporter of carnosine/L-histidine and L-histidine decarboxylase mRNAs. In conclusion, dietary addition of L-histidine and β-alanine increased antioxidant capacity, and increased meat derived imidazole dipeptide contents through the upregulation of gene expression of carnosine synthesis related enzymes. The combination of 1300 mg/kg L-histidine and 1200 mg/kg β-alanine may gain the satisfactory imidazole dipeptide contents in breast muscle of broilers.