The effects of dietary ellagic acid supplementation on growth performance, immune response, antioxidant activity, digestive enzyme activities, and intestinal functions in yellow-feathered broilers

Abstract This study was conducted to investigate the effects of dietary supplementation with ellagic acid (EA) on the performance, immune function, antioxidant activity, digestive enzyme activities, and intestinal functions in yellow-feathered broilers. In total, 288 healthy yellow-feathered broilers with an average body weight of 39 ± 0.24 g were randomly divided into four treatment groups. Broilers were given a corn-soybean meal basal diet supplemented with 0 (control group), 100, 200 or 400 mg/kg EA. In the finisher period and the overall period, the inclusion of 100, 200 and 400 mg/kg EA increased the average daily gain (P < 0.05), and the inclusion of 200 or 400 mg/kg EA decreased the feed/gain ratio compared with the control group (P < 0.05). The best immune activity (IgG and IgM concentrations) in serum was shown in the 200 mg/kg EA group (P < 0.05). Broilers fed with 200 or 400 mg/kg EA-containing diets exhibited higher serum catalase and glutathione peroxidase activities (P < 0.05) than control broilers. The inclusion of 200 mg/kg EA in the broiler diets increased intestinal chymotrypsin, pepsin, and lipase activities (P < 0.05). Broilers fed 200 mg/kg EA-containing diets had higher villus height in the jejunum and ileum, a higher ratio between villus height and crypt depth in the jejunum, and a deeper crypt in the duodenum compared to control broilers (P < 0.05). EA reduced the diamine oxidase activity and D-lactate concentration in serum. Furthermore, in birds fed EA-containing diets, the abundance of Rikenella and norank_f_norank_o_Clostridia_UCG-014 in cecum were decreased compared with control birds (P < 0.05). Moreover, in birds fed EA-containing diets, the levels of acetate, butyrate, and total short-chain fatty acids in the cecum were higher (P < 0.05) than those in control birds. These findings indicated that dietary EA had ameliorative effects on antioxidant capability, digestive enzyme activity, immune function and intestinal functions, which led to strengthened growth performance.