Evaluation of the Performance and Intestinal Gut Microflora of Broilers Fed on Corn-Soy Diets Supplemented With Bacillus subtilis PB6 (CloSTAT)

In this study, broilers provided feed containing 10⁹ cfu/t Bacillus subtilis PB6 in the finisher phase had a FCR similar to those on Zn bacitracin and significantly better than that of broilers provided nonmedicated feed with no added B. subtilis PB6 (P < 0.05). Over a 42-d period, broilers provided feed with B. subtilis PB6 had comparable feed intake and FCR as the antibiotic control. The counts of Lactobacillus species and Bifidobacterium species of broilers provided feed supplemented with B. subtilis PB6 were not significantly different from the number of these bacteria recovered from broilers provided feed supplemented with antibiotics. Numerically, up to 1- to 2-log₁₀ reduction in the number of Clostridium species recovered was observed in broilers provided feed supplemented with B. subtilis PB6 when compared with both negative and antibiotic controls. In terms of immunological response, birds provided feed supplemented with B. subtilis PB6 had significantly heavier bursas, heterophils with higher in vitro phagoctyosis for Escherichia coli, and lower ileal E. coli populations, indicating a potentiating role of B. subtilis PB6 as a probiotic on the chicken innate immune system.