PR - Potential For New Zealand Farmers To Reduce Sheep Greenhouse Gas Emissions Through Genetic Selection Tools (p18-26)
This research examined and quantified the effect on farm profit and emissions per kilogram of lamb product and per ewe when using different potential genetic selection tools.
A new selection tool was designed for farmers to select animals that produce fewer greenhouse gas (GHG) emissions while maintaining an ‘acceptable’ level of genetic progress in traits which enhance farm profitability.
Selection of sheep based solely on farm profit could potentially improve emission reductions per unit of product by 0.190 kg CO2e/kg lamb carcass weight (CWT). This is equivalent to a 0.61% reduction in total lamb emissions per annum (pa). Selection of sheep based solely on improving GHG emissions efficiency rather than farm profitability could potentially improve emission reductions per unit of product to 0.250 kg CO2e/kg lamb CWT per annum; equivalent to a 0.8% reduction in total emissions pa. However, doing this would come at the cost of 27 cents per breeding ewe reduction in annual genetic progress for farm profitability, due to sub-optimal emphasis on traits which enhance farm profits.
A selection tool would not be adopted by farmers if it caused an unacceptable level of farm profit progress to be lost. Altering the relative cost of each unit of carbon equivalents (CO2e) in the selection tool enabled the balance between GHG emissions per unit of product and farm profit progress to be changed.
A workshop involving key New Zealand sheep industry members was organised to discuss what an acceptable trade-off would be between progress made in farm profit and that in reducing GHG emissions per kilogram of product. A $25/t CO2e cost was deemed to provide an ‘acceptable’ trade-off. The acceptable trade-off produced an annual 0.199 kg CO2e/kg lamb CWT reduction in GHG emissions. This was predicted to achieve a 0.64% pa reduction in total emissions or 79.6% of the total possible reduction in GHG emissions using selection index tools, while still achieving 99.8% of the potential gains in farm profit progress.
Keywords: Greenhouse gases sheep genetic selection