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 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.
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 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:
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Recording full pedigree (sire and dam) will improve the rate of genetic gain in a ram breeding flock. Commercial producers are also interested in knowing dam pedigree as a way of monitoring individual reproductive performance in ewe flocks. Pedigree MatchMaker can be used in conjunction with sire joining records to determine pedigree and is less costly than DNA parentage tests or visually mothering-up lambs. In Sheep CRC trials, between 85–95% of lambs were matched to their dam with up to 96% accuracy using the Pedigree MatchMaker.
The Harvey family operate Gilgai Farms at Geurie in Central West NSW. They run a fine/superfine Merino flock and a Simmental beef herd on 2,800 hectares, which is grazed using Holistic Management principles.
The Harveys had been visually selecting, micron testing and fleece weighing their hoggets for some 15 years and were looking for the next productivity leap for their Merino flock. They decided to trial individual electronic identification technology so they could better identify highly productive animals for retention in the flock. Individual animal performance measures were collected prior to and at the 2015 ewe hogget shearing. For each ewe hogget the information collected was used to generate a Rampower Index Value and Ranking. This information was used to select replacement ewes for the flock and culls for sale.
This Conference combined world class science with its practical application.
Sheep CRC Practical Wisdom Notes is a series of technical notes to assist sheep producers to make sound decisions about technology and practices and then to have the know-how to implement their decisions.