PSXII-39 Probiotic on finishing phase of Nellore bulls fed tropical grass on dry season

Abstract

Abstract The objective was to evaluate the effects of Bacillus toyonensis on performance, carcass traits and its influence on ruminal and intestinal mucosa development of Nellore bulls fed tropical grass pasture on dry season supplemented with concentrate at 2.0% BW for 133 d. Four animals were slaughtered at the beginning of the experiment so that the initial carcass yield could be estimated. Eighty Nellore bulls (initial BW 354.02 ± 3.38 kg) were blocked according to body weight and assigned to one of two treatments: concentrate with Bacillus toyonensis (animals fed 1.6 x 109 UFC/day) or without (control group). Then, the remaining animals were allocated in 16 paddocks of Urochloa brizantha with 1.0 ha each (eight paddocks/treatment and five animals/paddock). At the end of the trial, bulls were slaughtered and carcass traits such as HCW, dressing percentage, 12th-rib fat thickness, carcass gain and carcass ADG were obtained. Tissue from the ventral sac and jejunum were collected and fixed in buffered formalin for evaluation of rumen papillae and intestine villi morphology. Data were analyzed using the GLM procedure of SAS. Paddock was the experimental unit for all analyses. Results indicated there were no significant difference (P > 0.05) between treatments for final BW (528.2 kg), ADG (1.333 kg) and G:F (0.165). No significant differences were detected between treatments for HCW (299.8 kg), dressing percentage (56.82%), and carcass ADG (0.885 kg). Conversely, control group showed a significant (P < 0.025) higher 12th-rib fat thickness (4.06 vs 2.97 mm). No significant effect on the development of the ruminal and intestinal epithelium was observed with the use of probiotic. Probiotic based on Bacillus toyonensis did not improve growth performance and carcass characteristics on finishing Nellore bulls fed tropical grass pasture on dry season.