Effect ofBacillus amyloliquefaciens-based direct-fed microbials and antibiotic on performance, nutrient digestibility, cecal microflora, and intestinal morphology in broiler chickens

Two hundred eighty-eight 1-d-old male Arbor Acres broilers were randomly allocated to 4 treatments to examine the effect of usingBacillus amyloliquefaciens-based direct-fed microbials (DFM) to replace antibiotics in the late growth stage on performance, nutrient digestibility, cecal microflora, and intestinal morphology in broilers. The experimental diets were (1) a negative control (NC) group fed a basal diet without any antibiotics; (2) a positive control (PC) group fed the basal diet with 200 mg/kg of zinc bacitracin; (3) a test group fed the basal diet with 200 mg/kg of zinc bacitracin from d 1 to 21 and 30 mg/kg of DFM from d 22 to 42 (DFM30); and (4) a test group fed the basal diet with 200 mg/kg of zinc bacitracin from d 1 to 21 and 60 mg/kg of DFM from d 22 to 42 (DFM60). The results showed that DFM30 and DFM60 increased BW gain and improved FCR as compared with NC group (P < 0.05). Generally, the PC, DFM30, and DFM60 groups showed increased apparent total tract nutrient digestibility for DM, CP, and AME as compared with the NC group. Both the DFM30 and DFM60 groups decreased cecalEscherichia coli population as compared with the NC group, and increased the population ofLactobacillus as compared with the PC group. The PC, DFM30, and DFM60 groups increased villus height and the ratio of villus height to crypt depth compared with NC. In conclusion, dietary supplementation withB. amyloliquefaciens-based DFM during d 22 to 42 may enhance performance by increasing nutrient digestibility and improving intestinal health in birds fed diets supplemented with zinc bacitracin from d 1 to 21.