New Zealand has been a world leader in the recent development of breeding sheep that belch out less methane – a relatively short-lived but potent greenhouse gas that contributes to climate change. The progress stems from more than a decade of research by AgResearch scientists - supported by the industry through the Pastoral Greenhouse Gas Research Consortium (PGgRc) and Beef + Lamb New Zealand Genetics, and the government via the New Zealand Agricultural Greenhouse Gas Research Centre (NZAGRC) - proving that some sheep naturally emit less methane as a product of their digestion, and that this trait can be bred for and passed down through generations.
After three generations of breeding, the lowest emitting sheep in a research flock produced close to 13 per cent less methane than the highest emitters, per kilogram of feed eaten.
However, questions have remained about whether this low methane trait means sacrifices for the health or quality of the animals, including quality of the meat that is derived for export around the world. AgResearch senior scientist Suzanne Rowe says research now published in a series of papers(external link) provides a valuable insight into what the implications for breeding for lower methane are.
“Once we knew we could breed for less methane, we set about determining what the impact on the animal might be from birth through to parenthood,” Dr Rowe says.
“The work was carried out in flocks across New Zealand using thousands of measures over several years to demonstrate that low methane emissions can be included into breeding goals without sacrificing other key health and performance traits.”
“What we have found is that breeding for lower methane, and the physiological changes we see in these lower emitting animals, do not negatively affect meat quality or those things meat producers are looking for in the animal carcass. The story has some complex biology behind it as we saw that low-emitting animals have different eating behaviours, tending to be grazers rather than gorgers - eating more feed than their high-emitting counterparts, even though the high emitters had bigger stomachs. This ‘little and often’ approach seems to favour laying down muscle instead of fat under the skin, whilst keeping the healthy fats that provide flavour, so meat quality is retained along with the reduced emissions.”
“We think the low-emitting animals may in fact have even greater economic value through decreased fat and increased meat yields.”
“This is critical because farmers need to know that if they are committing to breeding their animals for lower methane, that they are not going to go backwards in their productivity and earnings. This knowledge provides greater incentive to make changes on farms that contribute to New Zealand’s methane reduction goals, and to climate change globally.”
Research relating to the health of the sheep also suggests that breeding for low methane is unlikely to affect issues such as internal parasites (as demonstrated by faecal egg counts), the fertility of adult ewes and the survival of lamb litters. When it comes to wool, low methane breeding was favourable to fleece weight, while it was also favourable to the weight achieved by the animal before slaughter and its body condition.
The science is now enabling sheep breeders in New Zealand to breed for this low methane trait. Similar research is also now underway in New Zealand to achieve something similar in cattle, building on what has been achieved in sheep.
More research in this area is needed, researchers say, but these just-published findings are important for the ongoing science effort, for sharing with the industries, and for decision-making around climate change mitigations.