PSXII-20 Effects of association between monensin, calcium nitrate and tannin on enteric methane production in cannulated beef cattle

Abstract The objective of this experiment was to evaluate the association between different feed additives on ruminal fermentation parameters especially ruminal methane on cannulated beef cattle. Five Nellore cows, 480 ± 55 kg, ruminally cannulated were used. The experimental was a 5 x 5 Latin square design and the experimental unit was the animal within each period (n = 25 experimental units). The diets offered differed only by the inclusion or not of monensin, calcium nitrate or tannin, totaling five treatments: Control (without addition of additives), Monensin (30 ppm in the diet), Nitrate (3.0% of DM), Tannin (1.5% of DM) and Pool (combination of the three additives), being supplied in a basal diet with a concentrate: roughage (corn silage) ratio of 60:40. The study was divided into five periods, each one with 26 days. Sixteen days were used for adaptation to the experimental diets; ruminal fluid samples were collected at 0, 3, 6, 9 and 12h after feeding at 22nd day. To evaluate CH4 production and ammoniacal nitrogen balance, samples were incubated ex situ on equality ruminal conditions and then analyzed by gas chromatography and UV spectrophotometric, respectively. Data were analyzed using PROC MIXED of SAS and differences were declared significant at 5%. There was interaction between sampling time and treatment (P < 0001) and all the additives were efficient in decreasing the methane production in mol/g/hour (P < 0001), mol/kg/day (P < 0001) and g/kg/day (P < 0001). Comparing to the Control all additives decreased CH4 production, and decreases were 9.5% for monensin, 18.75% for tannin, 19.8% for calcium nitrate and 28.8% for the Pool (monensin, nitrate and tannin). Concentration and balance of rumen NH3-N was not affected by any treatments. It was possible to conclude that association of additives of different mechanism of action presented a partial additive effect.