Comparative analyses of rumen microbiomes to mitigate ruminant methane and improve feed utilization - Department of Agriculture Ref No 01200.059

Summary

The rumen microbiota of cattle and sheep are responsible for the bioconversion of feedstuffs through hydrolysis; then pathways involving both hydrogen-producing and hydrogen-consuming steps into various fermentation end products such as short chain fatty acids (SCFA). Methanogenic archaea (methanogens) consume metabolic [H] and produce methane, which accounts for a 2-12% loss of the metabolic energy from feed. Production gains to the livestock industry will be achieved through redirection of this metabolic energy into energy yielding products with a concurrent reduction in methane emissions.
Findings from this research have identified the variation in rumen microbial populations which helps explain the difference between low and high residual feed intake (RFI) as it pertains to lower methane production. The microbiota of low RFI animals were found to harbor similar dominant populations to those that were found in the gut of the low methane producing Tammar Wallabies. These populations are responsible for efficient turnover of soluble sugars without the release of H2 into the gut environment.
Monitoring of gene transcripts in low methane fermenters found an acetogen species responsible for redirection of H2 from methanogenesis to acetate production. Strategies that promote these species within cattle are likely to result in lower methane emissions and will revolve around increased starch and soluble sugar content in diets