Effects of Dietary Extract on Growth Performance, Immune Function, Antioxidant Capacity, and Intestinal Health of Broilers

extract (TCE) has many physiological functions and is potentially helpful in maintaining poultry health, but its specific effect on the growth of broilers is not yet known. This research investigated the effects of dietary extract (TCE) supplementation on growth performance, immune function, antioxidant capacity, and intestinal health in yellow-feathered broilers. A total of 288 one-day-old yellow-feathered broilers were divided into four treatment groups (72 broilers/group), each with six replicates of 12 broilers. The broilers were given a basal diet of corn-soybean meal supplemented with 0 (control), 200, 400, and 600 mg/kg TCE for 56 d. The results demonstrated that, compared with the basal diet, the addition of TCE significantly increased (linear and quadratic, < 0.05) the final body weight and overall weight gain and performance and decreased (linear and quadratic, < 0.05) the feed-to-gain ratio in the overall period. Dietary TCE increased (linear, < 0.05) the levels of IgM, IL-4, and IL-10 and decreased (linear and quadratic, < 0.05) the level of IL-6 in the serum. Dietary TCE increased (linear and quadratic, < 0.05) the levels of IL-2 and IL-4, decreased (linear and quadratic, < 0.05) the level of IL-1β, and decreased (linear, < 0.05) the level of IL-6 in the liver. Dietary TCE increased (linear and quadratic, < 0.05) the level of IgM and IL-10, increased (linear, < 0.05) the level of IgG, and decreased (linear and quadratic, < 0.05) the levels of IL-1β and IL-6 in the spleen. Supplementation with TCE linearly and quadratically increased ( < 0.05) the catalase, superoxide dismutase, glutathione peroxidase, and total antioxidant capacity activities while decreasing ( < 0.05) the malonic dialdehyde concentrations in the serum, liver, and spleen. TCE-containing diets for broilers resulted in a higher (linear and quadratic, < 0.05) villus height, a higher (linear and quadratic, < 0.05) ratio of villus height to crypt depth, and a lower (linear and quadratic, < 0.05) crypt depth compared with the basal diet. TCE significantly increased (linear, < 0.05) the acetic and butyric acid concentrations and decreased (quadratic, < 0.05) the isovaleric acid concentration. Bacteroidaceae and Bacteroides, which regulate the richness and diversity of microorganisms, were more abundant and contained when TCE was added to the diet. In conclusion, these findings demonstrate that supplementing broilers with TCE could boost their immune function, antioxidant capacity, and gut health, improving their growth performance; they could also provide a reference for future research on TCE.