Perna Junior, FlavioVásquez, Diana Carolina ZapataGardinal, RodrigoMeyer, Paula MarquesBerndt, AlexandreFriguetto, Rosa Toyoko ShiraishiDemarchi, João José Assumpção de AbreuRodrigues, Paulo Henrique Mazza2024-05-142024-05-1420201516-3598S1516-35982020000100803-scl10.37496/rbz4920190098https://repositorio-aptaregional.agricultura.sp.gov.br/handle/123456789/721ABSTRACT The objective was to assess the effects short-term use of monensin and Acacia mearnsii tannins as feed additives on nutrient intake, digestibility, and CH4 production in cattle. Six rumen-cannulated Holstein cows were distributed in two 3×3 Latin square experimental design, and each experimental period lasted 21 days. The basal diet was composed of corn silage and concentrate in a 50:50 dry matter (DM) basis proportion. Treatments were control, monensin (18 mg kg−1 of DM), and tannin-rich extract from Acacia mearnsii (total tannins equivalent to 6 g kg−1 of DM). Nutrient intake and apparent digestibility coefficients were not affected by the addition of monensin or tannins to diets. However, tannins showed a tendency to reduce crude protein digestibility. Monensin decreased CH4 emission by 25.6% (g kg−1 of body weight) compared with the control treatment. Monensin is more effective than Acacia mearnsii tannins in reducing CH4 emissions in the short term, considering a diet of the same roughage:concentrate proportion for cattle.animal nutritiongas productionmethaneruminantsArtigos