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Interpretive Summary: Effect of divergence in residual methane emissions on feed intake and efficiency, growth and carcass performance, and indices of rumen fermentation and methane emissions in finishing beef cattle

By Anne Zinn

A study recently published in the Journal of Animal Science investigated the effect of divergently ranking beef cattle for residual methane emissions on animal productivity, enteric emissions, and rumen fermentation. Global food production has benefitted from the ability of ruminant livestock to convert plant matter into high-quality sources or dairy and meat protein for human consumption, but ruminant derived food products have a much greater carbon intensity. Therefore, mitigation strategies to reduce enteric methane emissions from cattle have been a key research priority for livestock scientists in recent decades. Currently, there is little information available on the implications of ranking commercially representative beef cattle for residual methane emissions on animal productivity, feed efficiency, and carcass output, which prompted the present study.

Results demonstrated that residual methane emissions were the best predictor of  daily methane emissions and were the only methane trait observed to be independent of animal productivity. Additionally, ranking cattle in terms of residual methane emissions resulted in an approximately 30% difference between high and low emitting animals for methane output,  methane yield, and methane intensity. Results demonstrated that the differences in methane output among the residual methane emissions groups were associated with shifts in ruminal hydrogen dynamics resulting from a varied expression of microbial fermentation pathways associated with propionate production. Based on this information, further rumen microbial analysis is needed to understand the key microbes associated with phenotypic and/or genetic divergence for residual methane emissions, which could then facilitate the identification of potential microbial based biomarkers associated with the trait.

The full paper can be found on the Journal of Animal Science webpage.