The addition of condensed tannins to feces of beef cattle decreases the amount of in vitro gas production; but it is not clear if the same effect occurs when tannin extracts are fed to cattle. In this research, 30 Brahman bull-calves (230 ± 12.7 kg) were used to evaluate the influence of tannin extract supplementation on gas production in feces of receiving bull-calves. Fecal samples were taken from each bull-calf during 3 consecutive days, 40 g aliquots were placed in 600 mL plastic flasks, and 40 g of distillated water were added, flask were closed, and connected with a plastic pipe toward a 250 mL graduate glass flask inverted in a water bath. Flasks were incubated at 37°C during 24 h, and displaced water was recorded as the in vitro gas production. Other feces aliquots of 20 g were used to DM determination. Before receiving the treatments, the values of in vitro gas production (BGP) were computed as mL gas/g of feces DM basis. Bull-calves were placed in 6 dirt-floor pens, using a completely randomized design experiment, 3 treatments were randomly assigned: 1) corn silage based-diet (15.2% CP; 1.36 Mcal NEm/kg DM) without extra additives (Control): 2) Control plus 0.6% of condensed tannin extract (CT); and 3) Control plus 0.6% of hydrolysable tannin extract (HT). After 28 d on treatment diets, fecal samples were taken during 3 continuous days again, and after treatment fecal gas production (AGP) was measured as previously described. Each bull-calf was considered as the experimental unit. Results were analyzed by ANOVA for a completely randomized design. The BGP values were similar between treatments (P = 0.53) with a mean of 4.7 ± 0.45 mL/g of feces DM. The AGP values were not affected by treatments (P = 0.54) with a mean of 5.9 ± 0.49 mL/g of feces DM. Results indicate that when both, hydrolysable or condensed tannin are supplemented in the diet; they have no influence on the amount of gas produced in the feces of receiving bull-calves.