PSXII-18 - The probiotic containing Bacillus licheniformis and Bacillus subtilis improves feed efficiency in beef cattle

Abstract: The aim of this study was to investigate the effects of a probiotic containing B. licheniformis and B. subtilis on fecal characteristics, blood parameters, and performance in feedlot cattle. One hundred and forty-four single-sourced Angus x Nellore bulls (initial shrunk BW = 401 ± 45.5 kg) were randomly assigned to 1 of 2 treatments (4 bulls per pen; 18 pen replicates per treatment). Treatments consisted of a finishing diet containing no probiotic (CONTROL) or a diet with 2 g of probiotic/bull/d (PROB). The probiotic was composed of B. licheniformis CH200 and B. subtilis CH201 (3.2 x 10⁹ CFU/g; BOVACILLUS^TM). The diet was formulated using NASEM (2016) to provide an ADG of 1.9 kg/d (23% of corn silage, 65% of ground corn, 8% of soybean meal, 1% of urea, and 3% of mineral mix; DM basis). Bulls were adapted to the finishing diet over a 15-d period and fed for a total of 84 d. Fecal samples were collected on d 33 and 63. Blood samples were collected on the day of shipping to slaughter. Statistical analysis of experimental data was performed using the MIXED procedure of SAS 9.4. An α of 0.05 determined significance and an α of 0.06 to 0.10 was considered a tendency. No differences were obtained for initial BW, final BW, ADG, hot carcass, and dressing. Dry matter intake was reduced by 4% (P = 0.002) and G:F was increased by 6.3% (P = 0.036) in bulls consuming PROB diet. Regarding blood parameters, no differences were observed for glucose, haptoglobin, and LBP. There was a tendency of greater plasma urea (P = 0.09) in bulls consuming CONTROL diets. Fecal characteristics (DM, starch, N, pH, and scoring) were not different between treatments. Overall, dietary supplementation with B. licheniformis and B. subtilis improves feed efficiency in feedlot cattle.