Evaluation of Bacillus species as potential candidates for direct-fed microbials in commercial poultry

Increasing sociopolitical concerns with an- tibiotic use have led to investigations of potential alter- natives for food safety and growth promotion. Direct- fed microbials (DFM) including spore-based probiotics are amenable to feed inclusion and are extremely sta- ble. We isolated several Bacillus spp. from environmen- tal and poultry sources and tested them for their ability to reduce Salmonella in vitro. In a preliminary in vivo trial, day-of-hatch chicks and poults were randomly as- signed to the following treatments (24 birds/treatment): control and one of 8 DFM candidates at 10 6 spores/g of feed. Chicks and poults were tagged, weighed, and orally challenged with Salmonella Typhimurium (ST). Body weight gain and ST recovery were measured 11 d posthatch. Total percentages of ST-positive crop and ceca were significantly lower (P < 0.05) in at least 3 DFM candidates compared with control. Additionally, beneficial effects on BW gain were observed in at least 5 DFM candidates (P < 0.05) compared with control. In a second study, birds treated with NP122 (identi- fied as Bacillus subtilis) had significantly lower (P < 0.05) cecal ST than control and benefitted BW gain irrespective of the presence or absence of a Salmonella challenge. In conclusion, NP122 markedly reduced ST recovery and increased BW gain in both chicks and poults. This provides preliminary evidence that this isolate may have potential use as a DFM in poultry.