Objective  Effects of tannic acid (TA) supplementation in diet on the growth, slaughter performance, and gut microbiota of broilers were studied.

  Method  A total of 384 one-day-old healthy broilers with similar body weight were randomly divided into 4 groups with 12 replicates per group and 8 broilers per replicate. The birds were given either a control diet free of TA or diets containing 100, 150, or 200 mg·kg⁻¹ of TA for 42 d prior to slaughtering and testing.

  Result  (1) The TA supplementation tended to increase the broiler weight (P＜0.05). The inclusion of 200 mg·kg⁻¹ of TA in forage significantly increased the average daily feed intake of the broilers over control (P＜0.05). The feed/weight gain ratios decreased as the supplement increased on the 4 treatment groups (P＞0.05). (2) No significant effects of the TA supplementation were found on the dressing weight and the rate of dressing, evisceration, or breast muscle of the slaughtered broilers (P＞0.05). However, the presence of 150 mg·kg⁻¹of TA in diet significantly increased the muscle yield (P＜0.05). (3) TA exerted no significant effect on the α diversity of gut microbiota (P＞0.05), but a 200 mg·kg⁻¹ supplementation significantly increased the relative abundance of Lactobacillus in the intestines of the broilers.

  Conclusion  The dietary TA supplement improved the growth, proportionally increased the leg muscle, and boosted the population of beneficial enteric Lactobacillus of the broilers.