Dr Phil Vercoe
University of Western Australia
Tel: 08 6488 2552
This project has been completed.
The aim of this project is to develop practical techniques for measuring methane emissions from individual sheep on a large scale to enable the estimation of methane emissions as a function of genotype, management practices and environment. New and existing data of the sensitivity of enteric methane production and whole farm profit to different mitigation strategies will assist sheep producers to prepare for comprehensive emissions accounting.
More specifically, the project will:
Develop and validate new methods for measuring methane production enabling large scale screening of individual animals.
Estimate the heritability of divergent methane emission from sheep and establish preliminary estimates of phenotypic and genotypic correlations between methane emissions and animal production traits.
Quantify variations in methane emissions as a function of genotype and management options across a range of sheep production systems and agroecological zones and use this information to develop breeding and management systems for low methane emitting sheep.
Contribute to the development of an accurate basis for determining methane production from sheep for use in the National Carbon Accounting System and validate these functions against benchmarking studies of flock emissions.
The business case for this project is based on delivery Outcome 1 – Genetic selection and improved management will decrease methane emissions by 10% from 20% of sheep and make the sheep industry more competitive in an emissions accounting environment. It is likely that more efficient animals will produce less methane per unit of wool or meat, and MLA modeling has shown that decreasing feed requirements in terms dry sheep equivalent per head by 1% would result in a weighted NPV of $15.9 million per year for lamb and sheep meat production.
Sheep produce methane as a by-product of fermentative digestion in the rumen and hind gut. Efforts to lower emissions from sheep production systems are important for achieving long term domestic emissions targets and moderating their impacts on climate change. Research is needed to better understand the opportunities and costs of different mitigation strategies. Genetics is a powerful tool that can be used to make ongoing and permanent improvements to animals. The extent of the genetic improvements depends on the amount of variation that the trait exhibits and what proportion of this variation is heritable. Methane production is largely dependent on diet quality and feed intake, but differences in methane emissions per kg dry matter intake between individual sheep of 40 to 60% have been reported. The variation in
methane production between individuals is significantly higher than that recorded for conventional sheep production traits of approximately 10 to 20% within flocks, and provides an ideal opportunity for selection of low methane producers providing the trait is heritable. It has been shown that cattle selected for higher efficiency of feed utilization produce less methane per kg dry matter intake than cattle selected for lower efficiency. This suggests that methane production is heritable to some degree at least and reducing methane emissions and improving productivity through genetic selection is feasible. It is also important to define the relative importance of different management options compared to genetic variation. In addition to selection for methane production alone variation in characteristics such as growth rate, feed conversion efficiency and reproductive rates are likely to have major effects on methane production per unit of wool and meat produced.