PSXIV-22 The effect of adding different levels of Bromoform on enteric methane and rumen fermentation using continuous culture system in vitro.

Abstract The main objective of this experiment was to investigate the long-term effect of three different levels of bromoform, the active component in red seaweed algae, Asparagopsis taxiformis, on methane (CH4) gas production and rumen fermentation characteristics using the continuous fermenter technique in vitro. For this purpose, bromoform was added at 4 different levels of 0 (control), 0.14, 0.27, and 0.56 μl /Liter of rumen fluid /day. The treatments were arranged in a Latin square design with 4 periods of 10 days each. Treatment diets (50:50 forage to concentrate) were fed at 45 g/day dry matter (DM) in three equal portions. The first 7 days of each period were for adaptation, and last 3 days for samples collection. Samples were collected for the analysis of volatile fatty acids (VFA) and ammonia. Total gas production was measured through a 24h ANKOM batch culture using the fermenters content as rumen culture, and gas samples for the evaluation of CH4 production were also collected. The results showed that the addition of bromoform resulted in up to 98% reduction in CH4 production (P < 0.001) with all treatments compared to the control. Hydrogen (H2) production increased by 700% at the lowest concentration of bromoform. Ammonia concentrations showed a dose-dependent effect with the addition of bromoform, while it did not affect the dry matter digestibility. The total VFA was not affected by the addition of bromoform, though the molar proportions of individual VFAs were altered. A reduction in acetate, iso butyrate, and acetate to propionate ratio (P < 0.001) was observed with the addition of bromoform, while propionate and butyrate molar proportion increased significantly (P < 0.001) compared to control. In conclusion, bromoform can be used as a potential strategy to reduce CH4 without negatively impacting rumen fermentation, while it also can have a positive impact on ruminant productivity through increased propionate production.