Genomic Host Control of the Rumen Microbiome, Breeding for Optimal Productivity and Low Environmental Impact in Pastoral Livestock Systems

Microbes living in the gut of grazing livestock break down inaccessible roughage from plants into energy sources that can be used for growth, production and maintenance. During this process, hydrogen, given off as a waste product, combines with carbon and is breathed out as methane, a potent greenhouse gas. The microbes affect the amount of methane released and how well the animal extracts energy and nutrients from feed. The composition of the microbial mix is controlled by a combination of diet and the animal’s genetics. Here, we describe sequencing of the ruminant microbiome to determine rumen microbial community profiles (RMC) that are linked to livestock production and enteric methane emissions. In particular, we are interested in host control and the ability to select for animals likely to have an optimal microbial profile. We have shown that RMC are heritable and repeatable in sheep by measuring the same animals at multiple time-points. We have also shown that RMC are associated with enteric methane emissions and volatile fatty acid profiles. Aims are to look for signatures of selection across pastoral livestock to identify animals and diets with the best microbial composition for sustainable, productive farming with lowered environmental impact.