One of the main alternatives of additives to modulate the microbial population in the gastrointestinal tract (GIT), especially in the intestine, is the use of direct-fed microbials (DFM). This class of additives comprises all the feed products that contain a live or naturally occurring source of microorganism. The inclusion of DFM in diets of ruminants in the finishing phase may improve gain:feed by modifying the composition of the microbial community in the GIT to bring about a better symbiotic relationship with the host. These effects may be achieved with the use of Bacillus spp. bacteria, such as Bacillus licheniformis and Bacillus subtilis. Mixtures of these bacteria are able to foster positive effects in the finishing phase of beef cattle fed high-energy diets, which reinforces the need for studies that examine the effects and mechanisms of these species. In this study, feedlot Nellore × Angus bulls that received a DFM composed of B. licheniformis and B. subtilis had decreased dry matter intake, no influence on average daily gain, improved gain:feed, and an increase in expression of genes important for duodenal function.

Read the full article in the Journal of Animal Science.