Effects of dietary superoxide dismutase on growth performance, antioxidant capacity and digestive enzyme activity of yellow-feather broilers during the early breeding period (1–28d)

. The purpose of this study was to explore whether the addition of feeding superoxide dismutase (SOD) to yellow feather broilers in the early stages of growth could affect their growth performance, antioxidant properties, digestive enzyme activity and blood biochemical indices. A total of 320 male one-day-old yellow-feather broilers were evenly divided into 5 groups of 8 replicates each, with 8 chickens in each replicate. The control group was fed the basal diet, and four experimental groups were fed the basal diet + 100 mg/kg, 200 mg/kg, 400 mg/kg, and 800 mg/kg SOD, respectively. SOD was provided in powder form and the enzyme activity was 20 000 IU/g. Pre-feeding the basal diet for three days was followed by feeding the experimental diet for the trial period of 28 days. The results indicated that SOD significantly increased final body weight and average daily gain ( P < 0.05) and significantly decreased the feed:gain ratio ( P < 0.05) of broilers without affecting average daily feed intake ( P > 0.05). Dietary SOD increased total antioxidant capacity and glutathione peroxidase activity (GSH-Px) ( P < 0.05), reduced serum malondialdehyde ( P < 0.05) levels, and increased total SOD, catalase and GSH-Px ( P < 0.05) activities in the liver. The results demonstrated that dietary SOD supplementation improved the antioxidant capacity of broilers. However, SOD did not affect the activity of digestive enzymes (α-amylase, trypsin, lipase) in the duodenum, jejunum and ileum ( P > 0.05). In addition, SOD reduced serum alanine transaminase and aspartate transaminase ( P < 0.05) activity, indicating reduced burden on the liver. Based on these results, it can be concluded that the addition of different SOD concentrations to the diet can enhance the growth performance and antioxidant capacity of broilers. The addition of SOD provided the optimum effect in the range of 400–800 mg/kg.