Effects of traditional Chinese herbal feed supplement on growth performance, immunity, antioxidant levels, and intestinal health in chickens: a study on Ningdu yellow chickens

Traditional Chinese herbs have been widely researched as a green, safe, and effective feed additive for poultry. The purpose of this study was to investigate the effects of traditional Chinese prescription (TCP) based on various herbs in a specific ratio on the growth performance, carcass traits, immunity, antioxidant level, and intestinal health of Ningdu yellow chickens. A total of 420 female Ningdu yellow chickens were randomly divided into 5 groups, with 6 replicates of 14 each. The chickens were fed with a basal diet supplemented with 0 (CON), 0.2, 0.4, 0.6, or 0.8% TCP from d 43 to 105. Body weight, feed intake, and serum biochemical indicators were recorded at d 70 and 105, intestinal morphology and microflora of the carcass were determined at d 105. Compared to the control group, chickens fed with TCP, particularly at the level of 0.6%, showed improved average daily gain and breast muscle percentage, as well as a lower feed-to-gain ratio with statistical significance (P < 0.05). Between 43 and 70 d of age, chickens fed with TCP exhibited higher levels of serum glutathione peroxidase activity, total antioxidant capacity, and superoxide dismutase, particularly in the group fed with the 0.6% level of TCP (P < 0.05). Between 43 and 105 d of age, feeding chickens with 0.4 and 0.6% TCP resulted in a decrease in serum IL-2 concentration, and increase in the IL-4 content (P < 0.05). Chickens fed with 0.4, 0.6, and 0.8% TCP had significantly higher jejunum villous height (P < 0.05), TCP supplementation also led to a marked increase in the relative abundance of Bacteroidota compared to the control group (P < 0.05). Collectively, the study suggests that TCP supplementation can enhance immune and antioxidant functions, improve jejunum morphology, and positively impact cecum microflora in chickens. Based on these results, a level of 0.6% TCP could be considered an optimum level as a feed supplement for Ningdu yellow chickens aged 43 to 105 d.