Effects of dietary betaine supplementation on growth performance, meat quality, muscle fatty acid composition and antioxidant ability in slow-growing broiler chickens.

1. This study investigated the effects of dietary betaine supplementation on growth performance, meat quality, muscle fatty acid composition and antioxidant ability in slow-growing broiler chickens. 2. In total, 400, one-day-old female Xueshan broiler chicks were randomly divided into five groups with eight replicates of ten chickens each for 102 days. Broilers were fed a basal diet supplemented with 0, 125, 250, 500 or 1,000 mg/kg betaine. 3. Broilers fed betaine had better feed conversion efficiency and weight gain (P<0.05) and increased meat redness and yellowness 24 h after slaughter. Supplementation linearly decreased cooking loss and drip loss from breast muscle (P<0.05). Muscular resilience was improved and tenderness increased (P<0.05). Intra-muscular saturated fatty acids decreased, while total monounsaturated fatty acids and polyunsaturated fatty acids increased (P<0.05). Betaine increased activities of glutathione peroxidase (GPx) and total superoxide dismutase (SOD), glutathione (GSH) level, ratio of reduced glutathione/oxidised glutathione, and activity of scavenging hydroxyl radicals. It increased the activity of total antioxidant capacity (T-AOC) in the breast muscle (P<0.05). Moreover, supplementation up-regulated (P<0.05) mRNA expression levels of blood and antioxidant markers. 4. In conclusion, 1000 mg/kg betaine can be recommended as a supplement for slow-growing, Xueshan chicken.