Developing genetic evaluations of enteric methane for sustainable Irish beef cattle

Livestock production globally is a significant contributor to anthropogenic greenhouse gas emissions, particularly methane. Animal breeding provides a potential solution for reducing enteric methane emissions in a cost-effective, permanent, and cumulative manner. Initially, this research project focused on establishing a standard operating procedure for data handling of methane data recorded using GreenFeed Emission Monitoring (GEM) systems and phenotypic relationships between enteric methane and traits of economic importance in a finishing system. The focus of the research then shifted to estimating genetic parameters, including heritability and genetic correlations between methane and feed intake, using a large quantity of GEM system data. To date, 1,450 animals have undertaken methane measurement cumulating in 216,921 methane measurements. Additional measurements available on the population include detailed feed intake records recorded using Insentec feed boxes. Informative animals (n=1,155) were used to derive heritability estimates for methane and feed intake. Multiple definitions of the methane trait were analysed due to the varying length of test periods. The resulting six trait definitions included individual observations, 1-day average, 5-day average, 10-day average, 15-day average and a full test average methane trait. Methane heritability estimates ranged from 0.09 to 0.43 depending on trait definition, with larger averaging periods yielding greater heritability estimates. Each of the methane definitions was moderately correlated with dry matter intake ranging from 0.38 to 0.62. The results from this study have aided in the development of breeding values for greenhouse gas traits and the creation of a novel methane trait for future selection of sustainable livestock.