This study evaluated the effect of probiotic proenzyme ®, added to the mineral mixture in a weight gain of cattle in extensive grazing system. We used 40 animals, Nelore bulls (Bos indicus) aged approximately 12 months, randomly divided into 2 groups (20 animals / group): control group (CG) received only mineral mixture and probiotic group (GP) with added probiotic. Calves were weighed on days 0 and 30 from 30 to 90 days and 00 to 90 days. The results showed a significant increase in weight gain in animals only GP in the first 30 days