In vitro inhibition of rumen methanogenesis of a high-grain diet using lovastatin

One of the greatest environmental impacts from livestock is caused by enteric meth-ane emissions, a powerful greenhouse gas. In this context, some anti-methanogenic compounds have been evaluated, such as lovastatin (LOV), which is a hydroxy-methylglutaryl-CoA reductase inhibitor, a key enzyme for membrane synthesis of methanogenic archaea. This could be an option to mitigate methane emissions from ruminants. However, there are few in vitro studies and there is no general agreement about the methane mitigation by LOV under these conditions. Thus, the objective of this work was to evaluate the effect of LOV on in vitro methanogenesis and fermenta-tion characteristics in comparison with monensin (MON) and bromoethane sulfonic acid (BES). An in vitro batch incubation was carried out using a high-grain diet and bovine rumen fluid. The experimental design was completely randomized with three treatments, LOV, MON, BES, and a control with no inhibitor. The results demonstrated a favorable effect of LOV on rumen fermentation pattern in terms of methane mitigation (43.56 % inhibition) without affecting the volatile fatty acids (VFA) profile. However, the dose of LOV to obtain this result was very high compared to the doses used in the other treatments. MON was the most effective treatment based on the concentration/ inhibition of methanogenesis, followed by the BES; although, both compounds were associated to changes in the VFA profile.