The effect of dietary Bacillus subtilis supplementation on the growth performance, blood profile, nutrient retention, and caecal microflora in broiler chickens

The objective of this study was to evaluate the effects of the B. subtilis RX7 and B. subtilis C14 on the growth performance, blood profiles, nutrient retention, and caecal microflora of broiler chickens. A total of 288, 1-d-old Ross 308 male broilers were assigned to one of four dietary treatment groups for 35 days; the negative control (NC; basal diet with no antibiotic or B. subtilis), positive control (PC; NC + 40 ppm avilamycin), T1 (NC + 0.1% B. subtilis RX7 1.0×109 cfu/g), and T2 (NC + 0.1% B. subtilis C14 1.0×109 cfu/g). B. subtilis supplementation led to significantly higher weight gain than that in the NC. The serum haptoglobin concentration was lower in the Bacillus groups than in the NC and PC groups. The energy retention of broilers fed B. subtilis was significantly higher than that of the NC and PC broilers. The numbers of caecal Lactobacillus or Salmonella in the Bacillus groups were higher and lower, respectively, than those in the numbers in the NC and PC. The results showed that B. subtilis RX7 and C14 increased the weight gain, energy retention, and caecal Lactobacillus numbers and decreased serum haptoglobin levels and caecal Salmonella numbers in broiler chickens.