The era of the eco cow: Is it possible to breed for lower methane emissions?

The global livestock sector is estimated to be responsible for 7.1 GtCO2 equivalent every year – just under 15% of the global total a recent Chatham House report warned.

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Yet demand for animal protein is forecast to increase 76% by the middle of this century.

It’s clear that even though yields have already been pushed to historic highs, farmers must strive to produce more with even less than ever before.

Farmers have been selectively breeding for higher levels of agricultural productivity since animal husbandry began, aided over the last couple of centuries by recording, scanning, artificial insemination and now genomics.

But now researchers say they could be able to help shift breeding towards lower emission animals in the same way yields, fertility and milk solids have been targeted.

But while all of the measures will help to move the needle for agricultural emissions, some are much more effective in the short term than others.

For example, while genetic progress has been hailed by many – including DAFM – many others warn its progress is too slow and requires several generations before significant progress is made.

“Like compound interest”

One of the organisations at the forefront in Ireland includes the Irish Cattle Breeding Federation (ICBF), a non-profit organisation which since its foundation, which for the last 25 years has provided cattle breeding information services to the Irish dairy and beef industries in a bid to foster progress and genetic gain.

Dr Siobhan Ring, a geneticist at the ICBF, overseeing the recent genetic evaluations for methane emissions, disagrees with the criticism and says that rapid progress has already been made in a short timeframe.

She explained that unlike health and dietary solutions, the benefits of genetic gain do not die with that animal, but only increase as future generations of breeding build on the foundations established today.

However, “like compound interest”, she explains the benefits build with each new generation bred and are not lost with the death of the animal.

“Genetics is permanent. The benefits stack on top of each other. There are quite challenging targets in place for 2030 and 2050 and this is one aspect of a multi-faceted approach.

“It’s also complimentary to other strategies on farms – for example, in achieving better efficiency on farms.”

However, Dr Ring explained that this can be overcome by the likes of genomic selection, which allows the genes linked to certain traits to be identified and aggressively exploited for selective breeding.

Clodagh Ryan, a PhD student and geneticist at ICBF has been working to develop genomic evaluations of methane emissions, and other traits such as feed intake and calving ease.

A Blonde d’Acquitane bull was the individual top performer in terms of achieving lower emissions and there has been much boasting from the Lims about their combined top performance across the chart, but Dr Ryan explained the dataset really is too small to pull any hard conclusions over which breed is best.

“You're talking about bulls that only have a small number of progeny tested,” she said. “There's as much variation within the breed as there is across breeds. So when we're talking about breeding programs we want to identify the low emitters across all breeds.

“The idea is that farmers will be able to make more informed choices.” Interestingly, she explained that 11% of the differences in emissions were genetic differences, meaning that even within each breed there will be examples of blood lines which significantly outperform others.

“So we’re talking about heritability,” she said. “And making sure those genetics are brought forward.

The ICBF started methane recording in 2018, using “green machines” – a non-invasive device which offers cows feed while it records the methane emissions an cow produces as she eats. It’s a tool specially designed to overcome the practical challenges of recording the emissions of livestock out at pasture, which as you might imagine is much more difficult than recording the emissions of those kept in sheds.

Gene Ireland test bull The next step will be to scale up the number of animals measured and also capture data from different production systems, eventually it’s hoped a new index to allow farmers to identify the lowest-emission bulls could be launched by 2025.

“The animals that were measured through Tully were in the finishing period, so they were on a total mixed ration. What we need to do now is to scale that up to getting measurements for a grass-based system production system, which we have predominately here in Ireland.

“We also are going to need to get data on cows, and when you get that information, and with efforts to scale up genotyping, you'd be hoping that we'll be able to incorporate in the indexes in a few years.”

One big area of debate is whether low-emission animals really are more efficient, or simply producing less methane as a result of lower Dry Matter Intakes.

“That's part of the research that's ongoing, we obviously need to understand the correlations with older traits and the impact selection would have on them. And I suppose, as we will be making efforts towards inclusion in an index, you'd have to understand the dynamics there Wen you produce an index as a standalone as we have, it's just looking at methane; it's not looking at any of the other traits,” Dr Ryan said.

“It's about trying to tease out those relationships with other trades and work from there.” 

So, with promising work currently underway what kind of gains could be possible through selective breeding?

While Dr Ryan said she would be “very reluctant” to put any hard numbers on the gains possible, she explained that it could be quite substantial.

“If you consider that 11% of the difference in emissions was due to genetics. If for comparison, you take a trait, like fertility, fertility being a trait which is only about 3% heritable, and look at the gains that we made the dairy herd in the last ten to 15 years, that’s the kind of progress we hope could be possible.

“It’s really clear that the potential is there, and the only way we can capitalise on that is with more data.”

Further afield

Further afield, Dr Javier López Paredes, one of the team of researchers developing Spain’s industry-led programme to reduce dairy methane emissions from dairy cattle, agrees.

Spain hopes to launch its first official genetic evaluations for methane emissions next month, enabling farmers to identify more efficient and sustainable bloodlines. The project also hopes to further unravel the relationship between the microbiome, methane and feed efficiency.

One significant accomplishment has been the establishment of a national recording program to measure methane individually in commercial farms.

“Phenotypes are the key to success for genomic programmes. This allowed us to investigate the role of genetics in methane emissions and subsequently incorporate this objective into our breeding program,” Dr López Paredes told the Irish Examiner. 

“Methane emissions have been demonstrated to be heritable in our studies and also in other international research,” he said. "This means that the genes of the cow have some role on morphological and physiological characteristics determining the amount of methane that is fermented in the rumen, explaining around 20% of the differences between animals.

“Essentially, there are individuals that produce less methane while consuming the same amount of feed and producing the same amount of milk."

But to make the genomic predictions more accurate, the team says they need to increase the number of records in the population.

“Another challenge is the development of more accurate measuring devices that can measure methane production and concentration simultaneously at a large scale,” he said.

“Breeding programmes have undergone significant advancements in recent years, and the integration of new sources of information will be crucial for future progress.

“Our previous studies demonstrated that in order to reduce methane emissions from the dairy sector, methane emissions and feed efficiency should have a main role in the breeding programme,” he said.

“Therefore, there need to be clear and positive policies that encourage the sector to introduce new technologies (genetics, nutrition and infrastructure) for large-scale adoption of these practices to have a real impact on meeting emissions targets.

“But it is important to highlight that the livestock sector itself can only have a small impact, and the targets must be met by all sectors.

“In Spain, we have already seen a drastic reduction in the number of dairy cows from 1.5 million in the ‘80s to 800,000 today, mainly due to the improvement in production and the old EU quota. But it is also true that it has been compensated with beef cattle.”