Two experiments were accomplished with the objective to evaluate the in vitro efficiency of the propolis extract to inhibit the gas production from ruminal fermentation of different feeds. In the first experiment, 100 mg of ground brachiaria dry matter hay was incubated, in absence (0.2 mL of alcoholic solution at 70.0% in water) or presence of 0.2 mL of propolis extract (extraction of 3 g of propolis in triturated stone for each 10 mL of alcohol at 70%, for ten days, later on diluted for 50% of the same). The propolis extract, when compared to the control treatment, reduced the final total production and the final gas production for fiber carbohydrates. The specific digestion rate for fiber carbohydrates and non fiber carbohydrates was superior when the propolis extract was used. The reduction of the total gas production could be attributed to the effect of the propolis in increasing the molar propionate concentration, with consequent decrease of the acetate:propionate ratio. In the experiment 2, the objective was to evaluate different dilutions of the propolis extract (0.0, 13.7, 33.3, and 66.7%), in analogy to sodium monensin, added to reach 5.0 µM as a final concentration in the incubation tubes. It was observed significant effect of treatment, feed and feed:treatment interaction on the gas volume from the fiber and non fiber carbohydrates. There was no effect of the smallest propolis level (13.7%) on none of the evaluated diets, for final gas volume as for the fiber as non fiber carbohydrate. However, the largest level (66.7%) was efficient for all diets, for both types of carbohydrates, in addition to supplanting the monensin most of the time producing the least amount of gas.
gas; ionophore; propolis; ruminal fermentation
