🇬🇧 Is the key to reducing methane in genetics?

Introduction

Methane has a global warming potential 28 times greater than that of carbon dioxide. Ruminants, which produce methane, are responsible for over a third of the UKs agricultural greenhouse gases. There are significant differences in the volume of methane produced between different animals, which could suggest a genetic trait. The key to reducing methane could be in the genetics.

Why do genetics matter?

If methane emissions are a heritable trait, then that means genetics plays a role and livestock can be bred to produce less methane. It also means that this is a permanent characteristic as it is in their genetic makeup.

Other ways to reduce methane include changing diets or feeding an additive. But this only produces an effect whilst the animals are treated. As soon as the additive is removed or the diet is changed, the rumen microbes and methane emissions revert to their original quantities.

This would not be the case if methane was a genetic trait, and it would also mean that low emissions are passed on to the next generation. Scientists suggest that methane emission is 25% heritable. But it’s not as simple as that.

Are there differences between breeds?

There doesn’t seem to be a particular breed of ruminant that performs well when it comes to methane production. There is as much variability within breeds as there is between breeds.

Different breeds of dairy cow have been looked at regarding their methane production. Although there are some differences in methane emissions, these are largely down to the variability in feed intake and feed efficiency rather than the genetics of the cow.

In the case of beef cattle, there are obvious high and low emitters of methane. This seems to be down to significant differences in their rumen microbial populations. Although the genetics of the cattle themselves may not differ, those of the rumen microbiome do.

If a link can be found between the genetics of low emitting cattle and their rumen microbial populations, then that is something that could be bred for.

Here is a link to a video by America’s CBS news. It reports on the genetic research being conducted at Scotland’s SRUC to reduce methane emissions from cattle.

What genetic characteristics really matter when selecting for reduced emissions?

There are genetic characteristics that can be selected for which reduce methane emissions. Some practical possibilities include:

Increasing productivity in terms of offspring. Certain sheep breeds produce more than one lamb at each lambing. These ewes would produce less methane per lamb each year.
Use smaller breeds of animals as they tend to produce less methane.
Improving growth rates or meat production, consequently reducing days to slaughter. The methane produced over the animal’s lifetime would therefore be less.
Improving carcass quality, so less methane is produced per kilogram of saleable meat.
Parasitic burden is associated with greater methane output, therefore selecting for more parasite-resistant animals will reduce methane production.

Estimated Breeding Value

Estimated Breeding Values (EBV) are values that are given to an animal in order to predict the performance of its offspring. Typically, body condition score, weight and number of offspring are used to calculate the animal’s performance and its EBV.

In 2023/24, Ireland will be launching an estimated breeding value for its sheep based on methane. This will help them to determine which sheep are the highest methane emitters and which are the lowest. A trial of 4 farms is currently up and running.

The sheep will be awarded a score from 1 to 5 depending on the amount of methane they produce, with 5 being the best score.

This is part of the government’s plans to reach their net zero targets. However, it is also beneficial for the farmers because methane production is associated with a loss of energy and therefore production from the animal.

Are genetics really the answer to methane reduction and can it be looked at in isolation?

Genetics can certainly improve the productivity of our farms and therefore reduce methane emissions. It is important to look at the herd or flock as a whole rather than focusing on individual animals.

In sheep, genetic improvements for traits such as litter size and ewe longevity are the most effective at reducing methane production. Genetically improving production outputs in cattle and sheep, such as meat and milk, significantly reduces methane emissions over the animal’s lifetime.

But genetics don’t just apply to livestock. Plant lipids are known to reduce methane emissions from ruminants. For every 1% of lipid consumed by the animal in their diet, there is a resultant 5% reduction in methane.

In 2022, scientists at Rothamsted Research managed to edit the genes of Arabidopsis (rock cress) to stimulate lipid production. If this could be achieved in grazing crops and pasture, then it could provide a constant source of dietary lipids for livestock, thus reducing methane over the long term.

With the UK’s aim to get to net zero over the next couple of decades, genetics could help to provide the answer. However, like with most things, there are multiple ways to tackle the same problem. It is likely that genetics will be deployed alongside other methods for reducing our greenhouse gas emissions.

How can AgriWebb help?

AgriWebb helps to track key metrics around cattle and sheep productivity, including through offspring reporting. See our feature and reporting options here.

Want to learn more? Contact us.