Effects of Clostridium butyricum as an Antibiotic Alternative on Growth Performance, Intestinal Morphology, Serum Biochemical Response, and Immunity of Broilers.

The current study aimed to investigate the effects of Clostridium butyiricum on growth performance, intestinal morphology, serum biochemical response, and immunity in broiler chickens. A total of 330 commercial one-day-old, mixed-sex Ross 308 broilers were randomly divided into five treatment groups with six replicates per group. The broilers were fed the basal diet (CON), the basal diet with 150 mg/kg of aureomycin (AM), the basal diet with C. butyricum at 2 × 10 8 CFU/kg (CBL), the basal diet with C. butyricum at 4 × 10 8 CFU/kg (CBM), and the basal diet with C. butyricum at 8 × 10 8 CFU/kg (CBH). Results showed that the final body weight (BW) ( p < 0.01; p < 0.05), ADG from day 22 to 39 ( p < 0.05), and ADG from day 1 to 39 ( p < 0.01; p < 0.05) were improved in a linear and quadratic response with the inclusion of C. butyricum . There were no differences in feed conversion rate (FCR) among all groups ( p > 0.05). Supplementation with C. butyricum quadratically reduced the crypt depth at day 21 ( p < 0.01), linearly improved the villus height in the jejunum at day 39 ( p < 0.001), and linearly and quadratically increased the villus height to crypt depth (V/C) ratio in the jejunum at day 21 ( p < 0.01) and day 39 ( p < 0.01; p < 0.001). Dietary C. butyricum affected the thymus index at day 21 and day 39 (linear, p < 0.01), and the bursa of Fabricius index at day 39 (quadratic, p < 0.05). Compared to the AM group, the serum urea contents were decreased ( p < 0.05) but the IgG contents were increased in the CBL and CBH groups at day 21 ( p < 0.01); in addition, serum albumin (ALB) concentrations in all the C. butyricum -supplemented groups ( p < 0.01) and IgG concentrations in the CBM group were augmented at day 39 ( p < 0.05). In conclusion, dietary C. butyricum could enhance growth performance by improving jejunal morphology and stimulating immunity organ development in broilers, and could be an alternative to antibiotics in poultry feeds.