Effects of Lovastatin on Methane Production, Rumen Fermentation, and Microbial Composition In Vitro

This study examined the effects of purified lovastatin (LV) obtained from Monascus fermentation on ruminal fermentation, methane production, and microbial communities during a 48-h in vitro incubation. A fattening-sheep diet containing concentrate and roughage at 60:40 was treated with 0, 50, 100, or 150 mg LV/kg dry matter (DM). Samples from the control and 100 mg/kg DM treatments were selected for bacterial and archaeal 16S rRNA amplicon sequencing. Compared with the control, supplementation with 100 mg LV/kg DM significantly decreased methane production (mL/g DM) and methane content (%) by 22.1% and 12.7%, respectively, while increasing in vitro DM degradation by 4.9%. Cumulative gas production and total VFA concentration did not differ significantly among treatments. The molar proportion of propionate was higher at 150 mg/kg DM, while MCP concentration was higher at 100 mg/kg DM. Rikenellaceae RC9 gut group, Eubacterium, Succinivibrionaceae UCG-001, and Anaerovibrio were enriched in the LV treatment, whereas Methanococcus and Methanosphaera were enriched in the control. These results demonstrate the potential of lovastatin as a natural inhibitor of ruminal methanogenesis, with 100 mg/kg DM showing the greatest efficacy among the doses tested under the present in vitro conditions.