PSXIII-24 - Effect of inclusion of hay and concentrate containing monensin and methionine on in vitro methane production

Abstract: The objective of this study was to evaluate the effect of the inclusion of hay and Suplemento Total® concentrate as a substitute for corn on gas production and methane concentration in vitro. The experiment was conducted under anaerobic conditions using bottles that simulate the ruminal environment (ANKOM® Gas Pressure Monitor) containing artificial saliva, rumen liquid, and two g of substrates from each treatment: (MI) Control, 1.62 g of corn containing 9% of crude protein and 0.38 g of mineral mix and; (FMM) 1.02 g of Tifton 85 hay and 0.98 g of Suplemento Total concentrate (Suplemento Nutrição Animal®) containing 13.5% of crude protein, 0.32% of monensin and 0.63% of methionine. Duplicate substrates and duplicate blanks were fermented for each treatment in two runs, with a total of four repetitions per treatment. The accumulated pressure resulting from the fermentation was measured automatically over 48 h using the Gas Monitor software connected to the ANKOM® modules of each bottle. The conversion of the pressure to gas volume was calculated as follows: Volume (mL) = 2.3932 + 3.4053 × pressure (R² = 0.9146; n = 1.151). At the end of each run, a gas sample was collected from each bottle to measure methane concentration using gas chromatography. To obtain the methane production for every 100 mL of gas produced, the total volume of methane produced was multiplied by 100 and divided by the total gas production. Data were analyzed in a completely randomized design using analysis of variance (ANOVA) at α = 0.05. Was observed 23.86% of increase in gas production (64.79 vs 80.25 mL, P = 0.0072), 45.53% reduction in total methane production (46.50 vs 25.33 mL, P < 0.001), and 56.07% reduction in methane production for every 100 milliliters of gas produced (71.96 vs 31.61 mL, P < 0.001) in the FMM treatment compared to the MM, respectively. Improvement in the quality of the diet, as well as the use of monensin and methionine, increases the fermentation rate, which explains the increase in gas production. Linked to this, there is also a reduction in methane production by reducing the population of gram-positive bacteria, which are precursors of methanogenesis. Therefore, the inclusion of hay and Suplemento Total concentrate containing 0.32 percent of monensin and 0.63 percent of methionine in place of corn with mineral mixture increased gas production and reduced methane production in vitro.