Genetics to reduce methane emissions from Australian sheep

Summary

​Methane emissions by sheep are heritable. There are no strong (positive or negative) relationships between production traits (other than feed intake) and methane emissions. It is possible to use methane emissions in breeding objectives to reduce feed costs while at the same time limiting methane emissions even in the absence of a price on carbon. If there is a price on carbon, including methane measurements in a breeding objective maintains profit and further reduces methane emissions.

The trait that best suits a practical breeding objective is methane production (adjusted for weight), rather than methane yield (methane production divided by feed intake). Measurements of total methane production (adjusted for weight) using portable chambers have a high genetic correlation with measurements made in respiration chambers if the animals are eating the same feed. Essentially, this means that portable chambers can provide reliable data on methane emissions for the purposes of genetic selection. The best time (stage of life) to make methane measurements for genetic improvement is when the animals are dry (non-pregnant, non-lactating). Major genes affecting methane production are unlikely to be present, but use of genomic breeding values is possible.