Effects of dietary Bacillus amyloliquefaciens Y02 supplementation on the growth performance, immunity, intestinal morphology, and cecal microbiota of 1 to 42 days Langya chickens

BACKGROUND: Bacillus amyloliquefaciens (B. amyloliquefaciens) has garnered significant attention and application as a feed additive in poultry production for improving the chickens’ production performance and intestinal health. However, it remains unclear whether B. amyloliquefaciens influences the production performance and intestinal health of Langya chickens, a Chinese local chicken breed. The present study aims to investigate the effect of dietary B. amyloliquefaciens supplementation on the growth performance, immune function, intestinal morphology, and cecal microbiota in Langya chickens. RESULTS: Dietary supplementation with B. amyloliquefaciens Y02 had no effects on the final body weight, weight gain (WG), average daily gain (ADG), average daily feed intake (ADFI), and feed-to-gain ratio (F/G) of Langya chickens at 42 days of age in the treatment group (BAT) compared to the the control group (CON) (p > 0.05). However, the addition of B. amyloliquefaciens Y02 in the BAT group resulted in a 40% decrease in mortality of Langya chickens compared to the CON group. The serum immunoglobulin G (IgG) levels were increased by 31.56% and IgM by 32.36% in the BAT group in comparison to the CON group (p < 0.05), but tumor necrosis factor-α (TNF-α), interleukin-2 (IL), and IL-6 levels had no changes (p > 0.05). Compared to the CON group, the BAT group with B. amyloliquefaciens Y02 resulted in a 8.43% increase in the duodenal villus height (p < 0.01), a 24.13% increase in the duodenal villus height to crypt depth ratio (V/C) (p < 0.01), and a 15.83% decrease in the duodenal crypt depth (p < 0.05), as well as a 19.14% increase in the jejunal villus height (p < 0.01). Notably, the addition of B. amyloliquefaciens Y02 enriched the abundance of Bacteroides, Clostridum, and Alistipes at the genus level, resulting in the production of certain beneficial metabolites that play pivotal roles in maintaining the intestinal health, promoting the immune function, and reducing the colonization of harmful bacteria. CONCLUSIONS: This study demonstrates that B. amyloliquefaciens Y02 has many beneficial effects in terms of enhancing the immune defense mechanisms, improving the intestinal morphology, altering the cecal microbial composition, and maintaining the cecal microbiota balance in Langya chickens. CLINICAL TRIAL NUMBER: Not applicable.