@article {3672,
	title = {Impact of trait genetic gains on methane emissions from NZ beef and dairy farms},
	journal = {New Zealand Journal of Animal Science and Production},
	volume = {80},
	year = {2020},
	month = {09/2020},
	pages = {76-79},
	address = {Online},
	abstract = {The objective of this study was to provide estimates of the impact of trait genetic gains on methane emissions from NZ dairy and
beef farms. The effect of each trait on gross emissions (GE) and emissions intensity (EI) was modelled by estimating effects of trait
changes on per-animal feed consumption and the associated methane production, per-animal production and numbers of animals in
the system. In dairy, the annual gross emissions per breeding cow associated with genetic change were estimated to increase for all
traits except Residual Survival and Fertility. Conversely, emission intensity values were estimated to decrease for Milk Fat, Milk
Protein, Milk Solids, Residual Survival, Fertility and Body-condition Score (BCS) as genetic merit improves. In beef production,
increases in genetic merit for cow mature weight, cow BCS, cow calving ease and heifer pregnancy were estimated to increase the
annual gross emissions per breeding cow. Conversely, an increase in merit associated with stayability and gestation length reduced
annual gross emissions per breeding cow. The effect of increasing carcase weight on gross emissions depended on whether the
faster growth performance was used to slaughter the animal earlier, or to take the animal through to heavier finishing weights.

Keywords: methane; emissions intensity; gross emissions; dairy; beef},
	issn = {1176-5283},
	author = {Proctor LE and Archer JA and Sise JA and Zhang X and Crowley JJ and Amer PR}
}
