Influence of a dried Bacillus subtilis culture on intestinal microflora and performance of broilers and turkeys

Two experiments, each involving a 3 x 2 factorial design, were conducted with Large White turkeys to determine the influence of a Bacillus subtilis culture on body weight gain (BWG), feed efficiency (FE), livability and intestinal microflora. Four experiments with broiler chickens were also conducted to evaluate the protein-sparing effect of the B. subtilis culture when fed with different levels and sources of protein. The protease activity of the culture was hypothesized to improve protein digestibility. In the first experiment with female turkeys, the culture increased (P $\u3c$.01) B. subtilis counts in the crop and cecum, but failed to influence (P $\u3e$.05) Lactobacillus or Escherichia coli counts in the crop, jejunum and cecum. Feeding the B. subtilis culture did not significantly affect BWG and FE. However, two antibiotic supplements (44 ppm of Zn bacitracin or 44 ppm of penicillin-streptomycin) did increase BWG at 12 (P $\u3c$.05) and 16 (P $\u3c$.001) wk. In the second experiment, turkeys receiving the B. subtilis culture had greater (P $\u3c$.01) BWG at 12 wk, and improved (P $\u3c$.05) FE at 20 wk. Livability of turkeys receiving the culture was 3.8 and 1.4% higher in Experiments 1 and 2, respectively. The protein requirement of broiler chickens was apparently spared in Experiments 1 and 2 when B. subtilis was fed in low protein diets containing 5% meat and bone meal. Birds receiving low protein diets supplemented with the culture had increased (P $\u3c$.05) BWG and carcass weights, and improved (P $\u3c$.05) FE as compared to controls. When the culture was fed in the presence of increasing levels of poultry by-product meal (PBM) and feather meal (FM) in broiler diets (Experiments 3 and 4), BWG and FE were not affected (P $\u3e$.05). However, when the highest levels of PBM and FM (9.0 and 4.5%, respectively) were fed, addition of the bacterial culture resulted in a numerical increase in BWG and a similar improvement in FE. Livability was greater among birds receiving the B. subtilis in all four broiler experiments, which is consistent with results of the turkey experiments