The Role of Genetics in Reducing Methane Emissions

 

While carbon dioxide, nitrous oxide and methane are all important greenhouse gases, for sheep producers the most important is methane. Methane is an inevitable by-product from the fermentation process when ruminants convert forage into meat we can consume, often on land unsuited to other forms of food production.

Methane is created by microbes which break down forage in the rumen and is released when sheep eructate (belch). The amount produced will vary with intake and the type of feed consumed, but there are also differences between animals in the amount of methane produced.

What can we do?

The good news is there are already a number of ways that selective breeding can reduce the amount of methane produced by the flock relative to the amount of lamb produced.

• Lifting ewe productivity

The biggest impact we can make is by increasing the number of lambs produced per ewe over her working lifetime. This means selecting sheep that are genetically more prolific, express better lamb survival and have a longer productive life. 

• Reducing adult size

Smaller ewes produce less methane, in fact low methane producing sheep tend to have a smaller rumen, albeit one with a larger surface area. While selecting for rumen size is challenging, reducing mature size is easy; the trait is highly heritable and easily measured, though selection to reduce mature size must be balanced against requirements to lift lamb growth rates.

• Producing meat more efficiently

Genetic selection to reduce days to slaughter and increase the carcase yield of muscle relative to fat will reduce the amount of methane produced per kilogram of saleable meat. These are traits we can enhance by using rams with high breeding values for growth and muscling.

• Selecting for parasite resistance

Various studies have shown that parasitized sheep tend to be higher methane emitters. In maternal breeds selection for greater parasite resistance will contribute to reducing greenhouse gases.

In the future new ways to measure methane emissions will provide rams breeders with better tools to produce genetically superior sheep. A good example being the portable atmosphere chambers already used in research flocks. Selection for feed efficiency may also play a role, as it does in AHDB’s Beef Feed Efficiency Project.

While these new services provide alternative approaches for the future, in the short term it is reassuring that selection for many of the economically important traits within Signet’s National breeding programmes is already reducing methane emissions in the national flock.

For more information checkout this great publication by HCC