102 Award Talk: Bacillus-based direct-fed microbials as a strategic tool in beef cattle production.

Abstract The use of Bacillus-based direct-fed microbials (DFM) has shown relevant benefits for ruminant performance and health. In addition, the pressure over the use of antibiotics in the beef cattle industry opens the discussion of alternative feed additives that can provide profitability, performance, and sustainability for beef and dairy producers. Based on that, our research group has spent the past two years investigating Bacillus-based direct-fed microbials, evaluating various applications and combinations with other probiotic additives. In forage-based diets, adding the Bacillus-based DFM increased forage intake and digestibility of dry matter (DM), crude protein (CP), and neutral detergent fiber (NDF) compared to the control group. The results led to a greater amount of DM, CP, NDF, and acid detergent fiber (ADF) digested. The ruminal disappearance was also increased by the Bacillus-based DFM for DM and CP. The overall ruminal fermentation parameters were not affected by the inclusion of Bacillus-based DFM in the diet, however, animals that received the Bacillus-based DFM had increased ruminal pH at 16 and 20 h after feeding. The inclusion of Bacillus-based DFM in the diet tended to reduce the plasma concentration of glucose compared to the control group. In a 60-day feedlot pre-conditioning program, supplementation with a Bacillus-based DFM tended to increase dry matter intake in animals fed a 50:50 roughage-to-concentrate diet. Evaluating the effects of Saccharomyces cerevisiae (SC) fermentation product and Bacillus-based DFM in heifers fed corn silage-based diets, SC inclusion decreased the DM intake. In contrast, supplementation with a Bacillus-based DFM increased the molar proportion of acetate, the acetate-to-propionate ratio, and the fractional degradation rate. Additionally, Bacillus-based DFM inclusion tended to decrease the ruminal lag time and degradation rate compared with the control group. In summary, Bacillus-based DFMs have shown potential to enhance digestibility and, consequently, feed intake across various diets, which may positively influence animal performance.