Title: 386 Effect of essential oil and exogenous enzyme on feed intake, digestibility and rumen fermentation of finishing cattle fed different roughage sources
Abstract: Abstract Eight rumen-cannulated Nellore steers (327 ± 30 Kg BW) were used in a 4x4 duplicate Latin square to evaluate the effects of two feed additives (MON - Sodium Monensin 26 mg/kg DM vs. Crina® RumistarTM - combination of blend of essential oils - 90 mg/kg DM + exogenous α-amylase - 560 mg/kg DM, respectively; DSM Produtos Nutricionais Brasil S.A.) and two roughage sources at 10% of peNDF (CS - corn silage vs SB - sugarcane bagasse, on DM basis). Final diets contained 19.5% CS or 12% SB, corn grain (70.7 and 78.2% for CS and SB diets, respectively), 5.5% soybean meal, 4% mineral-vitamin mixture and 0.3% urea, on DM basis. The experimental periods had 14-d for adaptation and 5-d of collections. Data were analyzed with PROC MIXED of SAS and means compared by Tukey test. No interaction between additives and roughage sources was observed. Animals fed Crina® RumistarTM had 0.600 kg increase (P = 0.03) on DM intake and decreased (P = 0.01) apparent crude protein digestibility (CP; 75.3 vs. 77.5%, respectively) compared to MON. Animals fed SB presented greater apparent CP digestibility (77.6 vs 75.2%, respectively; P = 0.003) compared to CS. No difference in apparent NDF digestibility for additives and roughage source was observed. Animals fed Crina® RumistarTM had lower acetate concentration (P = 0.01) compared to MON on time 9, 12, 15, 18 and 21 hours. Animals fed CS had higher acetate:propionate (P = 0.03) compared to SB at all collection times–24 hours. Ruminal ammonia-nitrogen was lower (P = 0.01) in animals fed Crina® RumistarTM compared to MON. To use Crina® RumistarTM increased DM intake and decreased ruminal ammonia-nitrogen compared to monensin, suggesting a higher CP by-passing the rumen. Crina® RumistarTM increased DM intake without negative impacts on nutrients digestibility, regardless roughage source, thus a higher amount of nutrients reaches the intestine to be absorbed and animal performance can be increased.