Effects of in vitro-activated Clostridium butyricum FW1 on growth performance, intestinal barrier function, and gut microbiota of broilers.

The growing concerns regarding antibiotic residues and antimicrobial resistance have increased the demand for safe and effective alternatives to antibiotics in poultry production. Clostridium butyricum (C. butyricum), a butyrate-producing probiotic with beneficial effects on intestinal health, represents a promising alternative; however, the effects of in vitro-activated C. butyricum FW1 in broilers remain to be fully elucidated. This study evaluated the effects of dietary supplementation with in vitro-activated C. butyricum FW1 on growth performance, intestinal morphology, mucosal barrier-related gene expression, and cecal microbiota in broilers. A total of 360 one-day-old Arbor Acres male broilers were randomly assigned to 2 dietary treatments, with 10 replicates per treatment and 18 birds per replicate. Birds were fed either a basal diet (CON) or the basal diet supplemented with in vitro-activated C. butyricum FW1 at 1 × 109 CFU/kg for 42 d. Dietary supplementation with C. butyricum FW1 increased average daily gain and decreased feed conversion ratio during d 1 to 42 compared with the CON group (P < 0.001). At 21 d, birds fed FW1 had greater jejunal villus height and higher jejunal mucin 2 mRNA expression than CON birds (P < 0.05). At 42 d, FW1 supplementation increased villus height and crypt depth, with significantly improved on villus/crypt ratio in the duodenum and ileum (P < 0.01). Additionally, it upregulated jejunal mucin 5AC mRNA expression (P < 0.05). Cecal microbiota analysis showed that FW1 supplementation altered microbial community composition. Compared with 21 d, the relative abundance of Proteobacteria was significantly higher in the FW1 group at 42 d (P < 0.05), while Bacteroidetes showed a tendency to increase (P = 0.077). In addition, Faith's phylogenetic diversity index was higher in the FW1 group (P < 0.05). In conclusion, dietary supplementation with in vitro-activated C. butyricum FW1 improved growth performance, enhanced intestinal morphology and mucosal barrier-related gene expression, and modulated the cecal microbiota in broilers. These findings suggest that in vitro-activated C. butyricum FW1 may be a promising probiotic feed additive for improving intestinal health and production efficiency in broiler chickens. However, because a non-activated FW1 group was not included, the specific contribution of the activation process remains to be determined.