The rumen microbiome inhibits methane formation through dietary choline supplementation

Enteric methane (CH4) mitigation has often only limited success because of the complexity of the rumen microbiome. With this study we intended to manipulate and simplify the rumen microbiome by aiding one particular sub-population of rumen methanogens, the Methanomassiliicoccales (MMC) to out-compete other rumen methanogens. This simplified population might be much more vulnerable to CH4 mitigation strategies. We expected to achieve a dominant MMC population by drastically increasing the methyl-substrate availability for the MMC, especially since MMC has a lower hydrogen threshold than other rumen methanogens. For this goal, an experiment with an 8-fermenter in vitro Rumen Simulation Technique (Rusitec) was carried out across 15 days with four replicates.However, no dominance of MMC was achieved, but a sharp decline of all methanogens and the near complete mitigation (p<0.001) of CH4 emission at 97.9% and 96.5% was observed in choline chloride and choline bicarbonate infusion respectively compared to the control. The proportion of organic matter digested was decreased (p<0.01) by the treatments.