Timothy Houghton's MSc Defence

Assessing the Portability of Methane Production SNP Effects from Dairy to Beef Cattle Populations

Enteric greenhouse gas emissions from cattle represent a source of dietary energy loss and contribute to increasing climate concerns. This thesis had two objectives: to assess factors impacting methane production heritability estimates in cattle and sheep, and to evaluate if single-nucleotide polymorphism effects for methane production are portable from dairy to beef cattle populations. A meta-analysis was conducted across 43 studies with 51 unique heritability estimates for methane production. A linear fixed effects model was fitted, identifying the significant effects of animal sex, methane recording method, statistical approach used to estimate variance components, and additive genetic relationship matrix type used. For study two, the SNP effects for methane production were back solved from the estimated genomic breeding values of 643 genotyped Holstein cows at Ontario Dairy Research Centre. Two target beef populations were used to evaluate the prediction accuracy. Results demonstrated moderate to low ability to group beef cattle into tertiles according to their predicted methane emissions.