Bacillus-based direct-fed microbials may be an effective alternative to antibiotic growth promoters.
Environmental samples were pasteurized to remove vegetative cells, plated onto TSA or SPA for 24 or 72 h
and overlayed with soft agar containing S. enteritidis or C. perfringens. Isolates which produced antimicrobial activity against both pathogens were used to inoculate a solid state fermentation media and allowed to sporulate, to numbers greater than 109 spores/g and subjected to in vivo testing in both poults and chicks. In exp. 1 chicks fed isolates PHL-RW35 and PHL-RW41, at doses of 107 and 105 spores/g feed respectively, showed significant increases (p<0.05) in both Body Weight (BW) and Body Weight Gain (BWG). No significant differences in BW or BWG were noted in poults for any treatment. In this experiment, all groups were challenged with 105 cfu of S. typhimurium at day-of-hatch, no significant differences in Salmonella were noted between groups. In experiment 2 PHL-RW41 fed at 105 spores/g of feed significantly increased BWG by 8.3 and 11.7% in chicks and poults respectively. Isolate PHL-RW35 also increased BW and BWG in poults. These data indicate this approach for in vitro selection may be effective for screening and selection of Bacillus direct-fed microbials capable of causing an increase in BW and BWG in commercial poultry.