Abstract

Historic and potential future greenhouse gas (GHG) emission reductions resulting from genetic selection decisions in sheep have been quantified. Historic genetic trends in number of lambs born in maternal breeds and growth in terminal sire breeds were estimated to have reduced GHG emissions per kilogram of lamb carcass weight by 0.45% and 0.09% per year of genetic change, respectively. The implications of future selection using different indexes were also examined. Selection based solely on farm profits could lead to emission reductions per unit of product by 0.185 kg CO2-e/kg carcass weight, or a 0.59% reduction in lamb carcass weight emissions per annum. Selection of sheep ignoring profit and solely targeting reduced GHG emissions per kilogram of lamb carcass weight could lead to emission reductions of 0.242 kg CO2-e/kg lamb carcass weight, equivalent to a 0.77% reduction in total emissions per annum. However, doing this would come at a cost of 26.6 cents per breeding ewe reduction of 23.7% per annum in annual genetic progress. An alternative index that provides a balance between reducing GHG emissions and improving farm profits was estimated to produce an annual 0.193 kg CO2-e/kg carcass weight or a reduction of 0.62% reduction in emissions per annum in GHG emissions with minimal sacrifice in genetic improvement of farm profitability.

CI, Ludemann, TJ Byrne, JA Sise, and PR Amer

Proceedings of the New Zealand Society of Animal Production, Volume 71, Invercargill, 162-167, 2011