Greenhouse gas emissions (GHG) from broadacre sheep farms constitute ~16% of Australia’s total livestock emissions. To study the diversity of Australian sheep farming enterprises a combination of modelling packages was used to calculate GHG emissions from three sheep enterprises (Merino ewe production for wool and meat, Merino-cross ewes with an emphasis on lamb production, and Merino wethers for fine wool production) at 28 sites across eight climate zones in southern Australia. GHG emissions per ha, per dry sheep equivalents and emissions intensity (EI) per tonne of clean wool or liveweight sold under different pasture management or animal breeding options (that had been previously determined in interviews with farmers) were assessed relative to baseline farms in each zone (‘Nil’ option). Increasing soil phosphorus fertility or sowing 40% of the farm area to lucerne resulted in the smallest and largest changes in GHG/dry sheep equivalents, respectively (–66%, 113%), though both of these options had little influence on EI for either clean wool or liveweight sold. Breeding ewes with greater body size or genotypes with higher fleece weight resulted in 11% and 9% reductions, respectively, in EI. Enterprises specialising in lamb production (crossbred ewes) had 89% lower EI than enterprises specialising in fine wool production (Merino wethers). Thus, sheep producers aiming for lower EI could focus more on liveweight turnoff than wool production. Emissions intensities were typically highest in cool temperate regions with high rainfall and lowest in semiarid and arid regions with low aboveground net primary productivity. Overall, animal breeding options reduced EI more than feedbase interventions.

Item Type:	Refereed Article
Keywords:	greenhouse gas, sheep, beef, dairy, emissions intensity, mitigation, livestock, production
Research Division:	Agricultural and Veterinary Sciences
Research Group:	Agriculture, Land and Farm Management
Research Field:	Agricultural Systems Analysis and Modelling
Objective Division:	Animal Production and Animal Primary Products
Objective Group:	Environmentally Sustainable Animal Production
Objective Field:	Management of Greenhouse Gas Emissions from Animal Production
UTAS Author:	Cottle, DJ (Professor David Cottle)
UTAS Author:	Harrison, MT (Dr Matthew Harrison)
ID Code:	106443
Year Published:	2016
Deposited By:	Tasmanian Institute of Agriculture
Deposited On:	2016-02-10
Last Modified:	2018-03-29
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