Abstract
The present study investigated the effect of Bacillus subtilis DSM 29784 (Ba) and enzymes (xylanase and β-glucanases; Enz), alone or in combination (BE) as antibiotic replacements, on the growth performance, digestive enzyme activity, immune response and the intestinal barrier of broiler chickens. In total, 1200 1-d-old broilers were randomly assigned to five dietary treatments, each with six replicate pens of forty birds for 63 d as follows: (a) basal diet (control), supplemented with (b) 1 × 109 colony-forming units (cfu)/kg Ba, (c) 300 mg/kg Enz, (d) 1 × 109 cfu/kg Ba and 300 mg/kg Enz and (e) 250 mg/kg enramycin (ER). Ba, Enz and BE, similar to ER, decreased the feed conversion rate, maintained intestinal integrity with a higher villus height:crypt depth ratio and increased the numbers of goblet cells. The BE group exhibited higher expression of claudin-1 and mucin 2 than the other four groups. BE supplementation significantly increased the α-diversity and β-diversity of the intestinal microbiota and markedly enhanced lipase activity in the duodenal mucosa. Serum endotoxin was significantly decreased in the BE group. Compared with those in the control group, increased superoxide dismutase and glutathione peroxidase activities were observed in the jejunal mucosa of the Ba and BE groups, respectively. In conclusion, the results suggested that dietary treatment with Ba, Enz or BE has beneficial effects on growth performance and anti-oxidative capacity, and BE had better effects than Ba or Enz alone on digestive enzyme activity and the intestinal microbiota. Ba or Enz could be used as an alternative to antibiotics for broiler chickens.