GREENHOUSE GAS ABATEMENT & FEED EFFICIENCY

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.