Methane Opportunity – animal genetics can play a big role

While fossil fuel emissions make up around 80% of greenhouse gas (GHG) emissions, for livestock production, methane (CH4) produced via enteric fermentation by ruminants is one of the largest contributors to agricultural greenhouse gases.

The majority of the world’s largest food companies are committed to the Science Based Targets initiative (SBTi) to significantly reduce GHG emissions by 2030 with many committed to net zero by 2050. Therefore, delivering reductions in ruminant CH4 production becomes critical to the entire food supply chain, positioning dairy as a high quality, nutrient dense food with a lowering carbon footprint.

Genetic selection of low CH4 emitting cows has been viewed for many years as a potential method to reduce the greenhouse gas emissions of the dairy sector as genetics has the benefit that selection effects are additive and permanent.

In April 2023, Lactanet in Canada launched the world’s first genomic evaluations for Methane Efficiency in Holstein dairy cows with the potential to reduce methane emissions 20-30% by 2050. This would equate to a 15 mega ton reduction of CO2 by 2050 for the Canadian dairy industry’s one million cows.

Leading researchers at the University of Guelph, Lactanet and Semex, using data collected over the past 12 years, discovered a 30% difference above or below average can be seen between cows, meaning two cows in the same herd can differ in their CH4 emissions by up to 110kgs per year. And with the cows’ genetics, also known as the heritability, controlling 23% of this variation, the potential to reliably breed lower methane emitting cows becomes reality.

The average reliability of Methane Efficiency for genotyped young bulls and heifers exceeds 70%. Methane Efficiency is expressed as a Relative Breeding Value (RBV) averaging 100 and ranging from 85 to 115. For every 5-point increase in a sire’s RBV for Methane Efficiency, daughters are expected to produce approximately 3 kilograms less CH4 per year. This equates to a 1.5% reduction in CH4 emissions, and a herd can achieve a 20% to 30% reduction by 2050 through genetic selection. Moreover, Methane Efficiency does not have a significant undesirable correlation with any other trait, including production yields and feed efficiency.

The provision of methane efficiency indices on all male and female cattle, will enable farmers to start using this information to select lower CH4 emitting cows and bulls for breeding, helping to contribute to lower emissions in the global dairy sector in the longer term. To read more detail please see full paper Symposium Review: Development of genomic evaluation for methane efficiency in Canadian Holsteins in the American Journal of Dairy Science. The fact this research confirms that genetics can be another tool in our toolbox for methane reduction is great news and we now need to work on how to include this in the sector’s emissions reporting.

With thanks to Drew Sloan, who presented this at a Semex International Dairy Conference, January 2024