The potential impact of breeding strategies to reduce methane output from beef cattle

The present paper provides an indication (using selection index theory) of the contribution of genetics to a reduction in methane emissions through the current selection for productivity traits (defined as the inherent rate). This is then compared with potential new approaches that incorporate measurements or estimates of methane production as selection criteria. The predicted value of the inherent reduction in methane at a price (all costs and prices are in Australian dollars) of $25/t carbon dioxide equivalent (CO2-e; methane × 25) is $0.38/cow mated per year. The direct value of the estimated annual genetic gain in productivity (about $3/cow mated) is about eight times the value of the savings in methane. The value of the carbon savings doubles to ~$0.75 if methane yield (methane per unit feed intake) is included in the index. This is due to a reduction in methane emissions of 0.78% of the mean (1.20 kg methane/cow mated per year at a carbon cost of $25/t CO2-e) which increases to 1.0% at $50/t CO2-e. If selection is on methane alone, the annual response is ~1.45%, which is valued at $1.39 at a price of $25/t CO2-e. However, adoption is less than 100% at the breeder level, so that realised gains will be less than predicted here.