Rumen microbiome response to methane inhibition

Rumen microbiota ferment feed into various by-products, some of which are used by methanogens to produce enteric methane (CH4), a potent greenhouse gas (GHG) that significantly contributes to climate change. The use of CH4 inhibitors, such as Asparagopsis spp. and 3-nitrooxypropanol (3-NOP), in ruminant feed has been shown to be effective in reducing methanogenesis. However, inhibition of enteric CH4 leads to inconsistent productivity gains, partly due to the shift in significant fermentative microbes away from acetogenesis and the inability to convert increased ruminal dihydrogen (H2) spared from methanogenesis into absorbable nutrients beneficial to the host animals. Mitigation of CH4 synthesis paired with redirection of ruminal H2 to preserve normal rumen functions could be one of the most promising strategies to improve ruminant productivity while feeding CH4 inhibitors. This review highlights the growing knowledge of the rumen microbiome response to CH4 inhibition and explores the potential benefits of co-supplementing CH4 inhibitors with electron acceptors to optimise rumen function as a future direction to supporting the voluntary on-farm adoption of anti-methanogenic feed additives (AMFAs) across livestock systems.