Reprogramming hydrogen metabolism for methane mitigation in dairy cows: mechanistic insights from polyphenols using...

Area of Science:

• Agricultural Science
• Microbiology
• Environmental Science

Background:

• Enteric methane emissions from ruminants are a major agricultural greenhouse gas source.
• Phytochemicals like grape seed proanthocyanidins (GSP) show potential as natural antimethanogenic feed additives.
• The precise mechanisms of phytochemical action in reducing methane are not fully understood.

Purpose of the Study:

• To comprehensively elucidate the microbiological and functional mechanisms of phytochemical-induced methane mitigation.
• To investigate the effects of GSP on rumen microbial communities and their metabolic functions.
• To establish a mechanistic framework for GSP's antimethanogenic activity.

Main Methods:

• Integrative meta-omics (metagenomics and metatranscriptomics) applied to both in vivo and in vitro experiments.
• Analysis of microbial community composition, abundance, and gene expression.
• Quantification of methane emission intensity in lactating dairy cows.

Main Results:

• GSP supplementation significantly reduced methane emissions, decreasing emission intensity by 16.5% in dairy cows.
• GSP altered microbial communities, decreasing methanogenic archaea and increasing specific hydrogenotrophic bacteria.
• GSP upregulated genes involved in reductive acetogenesis, nitrate ammonification, and sulfate reduction, redirecting hydrogen flux.

Conclusions:

• GSP modulates rumen microbial composition and function to suppress methanogenesis by enhancing bacterial electron sinks.
• This study provides the first meta-omics-based mechanistic understanding of phytochemicals mitigating methane in ruminants.
• Polyphenols like GSP offer a promising strategy for developing sustainable feed additives to reduce agricultural greenhouse gas emissions.