Impact of monensin, virginiamycin, trace minerals, and yeast combination on animal performance, carcass and meat characteristics of finishing feedlot bulls fed high grain diet.

This study was realized to evaluate the influence of monensin, virginiamycin,trace minerals and yeast combination on animal performance, feed efficiency, in situ digestibility, feeding behavior, and carcass and meat characteristics from bulls finished in feedlot fed high-grain diet. A total of 36 (European vs. Nellore) bulls at 24 ± 3.2 months of age and with a body weight (BW) of 385.5 ± 3.84 kg were used in a completely randomized design. The four experimental diets were: CONT - without additives; MONE - inclusion of 30 mg of monensin/kg of DM; MOVI - inclusion of 30 mg of monensin + 30 mg of virginiamycin/kg of DM; MOMY - inclusion of 30 mg of monensin/kg of DM + 0.3 g/kg of BW of trace minerals and yeast. Final body weight was higher (P < 0.05) for the bulls fed MOVI (558.7 kg) and MOMY (554.6 kg) diets, intermediate for bulls fed MONE (529.3 kg) diet, and lower for bulls fed CONT (514.6 kg) diet. Likewise, the average daily gain was higher (P < 0.01) for bulls fed MOVI and MOMY (2.02 kg/d), intermediate for bulls fed MONE (1.72 kg/d), diet and lower for bulls fed CONT (1.57 kg/d) diets. Dry matter intake and other nutrients were similar (P > 0.05) among treatments. However, feed conversion improved (P < 0.05) for bulls fed MOVI and MOMY diets. Animals fed MOVI and MOMY spent more time ruminating compared to animals fed CONT and MONE (P = 0.034) diets. The carcass weights, carcass dressing and backfat thickness were greater (P < 0.05) for the bulls fed MOVI and MOMY diets. In conclusion, the inclusion of monensin or a combination of monensin + virginiamycin or monensin + trace minerals and yeast resulted in higher animal performance and improved feed efficiency.