Effects of Mongolian 'Bergenia crassifolia L. (root)' extract on rumen methane emission reduction and microbial community.

Objective: The study investigates the effects of Mongolian plants on reducing methane emissions, fermentation parameters, and microbial communities in grazing systems.

Methods: Initially, various Mongolian plants were screened to identify those that effectively reduced methane production in vitro. The most effective plant was selected for the extraction of its active components, resulting in a solid extract with a quantified concentration of its bioactive compounds. Extracts of 0, 1.0, 2.0, 3.0, 4.0, and 5.0% of DM were added, respectively, and then subjected to in vitro rumen fermentation trials using rice straw and alfalfa as substrates to evaluate their methane reduction effects. Key metrics assessed included gas production, methane production, and rumen fermentation parameters. After the fermentation experiments, we extracted DNA from the rumen fluid for quantitative PCR and 16S high-throughput sequencing analysis.

Results: Bergenia crassifolia L. (root) was identified as the plant exhibiting the most significant methane reduction capability with approximately 70% condensed tannins in its extract. This extract significantly decreased methane production in the rice straw substrate (p<0.01), while only the highest dose had a notable effect in the alfalfa substrate (p<0.01). Furthermore, low doses of the extract did not significantly impact rumen fermentation parameters. The genera Ruminococcus and Christensenellaceae R-7 were identified as the principal contributors to the reduction of methane emissions (p<0.01).

Conclusion: Bergenia crassifolia L. (root) was more effective in reducing methane emissions from low-quality roughage compared to high-quality roughage, with an optimal addition concentration of 1.0% for low-quality feed. This plant presents a promising new strategy for mitigating rumen methane emissions in grazing systems.