Effects of Bacillus amyloliquefaciens F1 postbiotics on growth performance, serum biochemistry, intestinal morphology and intestinal microbiota of yellow-feathered broilers.

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.