Comparison Between Sheep and Diary Cattle GWAS for Methane Emissions

Enteric methane emissions are the most important greenhouse gas emitted from the pastoral industry. With the availability of high-density genotyping in livestock it is possible to search for quantitative trait loci associated with methane emissions. Two datasets were available for analysis. The first involved 1,513 New Zealand dual purpose sheep fed a pelleted diet at 2.1 times maintenance and measured in respiration chambers for two 48hr periods, 14 days apart. These animals are from a divergent selection line programme selecting for high and low methane emissions. The progeny plus their sires have been genotyped with either the Illumina 50K ovine beadchip or the new Illumina 600K ovine beadchip. The second data set involved 1,726 dairy cows from the extensively phenotyped Langhill herd at Scotland Rural University College. Data on milk yield, live weight, body condition score and feed intake were used to calculate a predicted methane emission (PME) estimate. Genotypes were available on 669 dairy cows and 32 sires from the Illumina 50K bovine beadchip. The data is currently being analysed in a genome wide association study for using de-regressed parent average removed estimated breeding values. Comparison of regions identified from each analysis could identify common genetic pathways influencing methane emission in both species.