This study aimed to investigate the effects of dietary supplementation with pomegranate peel powder (PP) on the growth performance, serum biochemistry, antioxidant capacity, intestinal microbiota, and duodenal mucosal metabolites of yellow-feathered broilers. A total of 360 yellow-feathered broilers were randomly divided into three groups, with their diets supplemented with different levels of PP (0, 1, and 4 g/kg) for 42 days. Dietary supplementation with PP significantly increased the average body weight and average daily gain of yellow-feathered broilers during the periods of 1-21 and 22-42 days, while reducing the feed conversion ratio (p < 0.05). It also decreased the serum levels of aspartate aminotransferase, alanine aminotransferase, creatinine, and uric acid, increased the activities of glutathione peroxidase and superoxide dismutase, and reduced malondialdehyde content in the serum, liver, and intestinal mucosa (p < 0.05). Furthermore, PP supplementation promoted the mRNA expression of farnesoid X receptor, peroxisome proliferator-activated receptor alpha, fatty acid-binding protein 4, epidermal growth factor/epidermal growth factor receptor, and B-cell lymphoma 2, while decreasing the mRNA expression of caspase-1 and interleukin-1 beta (p < 0.05). Regarding mucosal metabolites, PP supplementation increased the contents of polyunsaturated fatty acids (cis-11-eicosenoic acid, cis-13,16-docosadienoic acid, and cis-11,14-eicosadienoic acid), prostaglandin E2/G2, and secondary bile acids (apocholic, hyodeoxycholic, 7-ketodeoxycholic, and omega-muricholic acids) in the mucosa (p < 0.05). In terms of cecal microbiota, PP supplementation increased the β-diversity index (p < 0.05), elevated the relative abundances of Bacteroidota, Alistipes, Bacilli, and Actinobacteriota, and reduced the relative abundances of Clostridia and Gammaproteobacteria (p < 0.05). In conclusion, dietary supplementation of PP can improve intestinal health and growth performance of yellow-feathered broilers by regulating the composition of the gut microbiota.

The extensive use of antibiotics in poultry production has contributed to antimicrobial resistance, creating a need for safe and stable alternatives. This study evaluated the effects of Bacillus amyloliquefaciens F1 postbiotics (BAP) on growth performance, antioxidant status, intestinal morphology, and cecal microbiota in yellow-feathered broilers. A total of 360 one-day-old male broilers were randomly and evenly assigned to three dietary treatments for 63 days: a basal diet (control, CON), the basal diet separately supplemented with 100 g/t (BAP100) and 150 g/t (BAP150) of BAP. At 21 days, broilers in BAP-supplemented groups exhibited significantly higher body weight (approximately 7.5 % increase, P < 0.01) and average daily gain (approximately 8 % increase, P < 0.01), with a 9 % reduction in feed conversion ratio (P < 0.05) compared to the CON group. The BAP100 group maintained greater body weight at 42 days (6 % increase, P < 0.05). Serum and hepatic antioxidant enzyme activities were significantly enhanced in BAP groups, including glutathione peroxidase (GSH-Px, +24 %, P < 0.01), catalase (CAT, +28 %, P < 0.01), and total antioxidant capacity (T-AOC, +31 %, P < 0.01), while malondialdehyde (MDA) levels declined by approximately 40 % (P < 0.05). Histological examination revealed improved intestinal morphology, characterized by increased villus height and villus-to-crypt ratios in the jejunum and ileum (P < 0.05). Additionally, BAP supplementation up-regulated MUC2 mRNA expression (P < 0.05) and modulated the abundance of specific cecal bacteria at 63 days (P < 0.05), without altering overall microbial diversity. In conclusion, dietary supplementation with Bacillus amyloliquefaciensF1 postbiotics improved growth performance and intestinal health in yellow-feathered broilers, with the 100 g/t dose yielding the most pronounced early benefits.