For R:C ratio of 70:30, nitrate increased ammonia concentration compared with control for all diets (Table 4). Fumarate decreased ammonia concentration for CC and CKC, but not for CAC and CAKC compared with control. Without addition of any additive, nitrate was greater for CAC than other diets. Ammonia concentration was greater for CAC and CAKC than for CKC and CC when fumarate was added, and it was lower for CKC than for other diets when nitrate was added. For roughage and concentrate ratio of 40:60, nitrate also increased the concentration of ammonia in the media for all diets, but fumarate decreased ammonia concentration for CKC only, with respect to control (Table 5). Ammonia concentration was higher for CAC than other diets when no any additive was added. With nitrate and fumarate, ammonia concentration was lowest for CKC, followed by CAKC and CAC, and then CC.