Methane is an immensely challenging problem for the Irish dairy and beef sectors, but science is providing the means – mainly through new feed additives and breeding techniques – to reduce associated emissions.
When ruminant animals like cattle and sheep digest food, they produce methane, a greenhouse gas 86 times more powerful than carbon dioxide. This fact is an existential threat to the dairy and cattle industries, but research breakthroughs suggest they can each pivot to a sustainable future.
Details of promising new scientific strategies were outlined by researchers based in Ireland and Britain at a recent online briefing organised by the Science Media Centre Ireland on scientific approaches to reducing methane from farm animals.
Dr Sinéad Waters is a microbiologist at the University of Galway, who investigates the microbiome; the community of microbes found in the rumen of animals such as cattle and sheep, which acts like a fermentation chamber.
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The microbiome, says Waters evolved the ability over centuries to break down low-quality forage (plant material fed to livestock) which resulted in high-quality meat and milk products from livestock. The problem is that this process produces methane gas, which contributes far more than CO₂ to global warming in the short to medium term – the other main source of methane emissions is leakage associated with fossil fuel production.
“Ireland has a large number of cattle, around seven million, which are critical to the success of our agri-food sector,” adds Waters. “In order to meet our 2030 climate action plan targets to reduce agricultural greenhouse gas emissions by 25 per cent it is essential to implement effective technologies to reduce methane emissions from Irish farms.”
There are significant efforts at EU and Government level to tackle the problem. Waters co-ordinates several projects funded by the Department of Agriculture and by the EU Horizon programme that evaluate any new emerging methane mitigation strategies to assess if they apply to EU farmers generally, and to Irish agriculture where animals graze outdoors on grass throughout the year.
Irish agriculture, along with that of Britain, has livestock animals outside, grazing on grass throughout the entire year. That means new feed additives, to be suitable in these islands, must allow for animals to always be outdoors.
“We are trying to develop feed additives for grazing systems,” says Waters. “These include boluses – which are a capsule that can be inserted into the rumen – that can be delivered throughout the day and would not require animals to be brought indoors for the feed additive to be inserted.”
She highlights promising work in New Zealand where a bolus is being tested that contains bromoform, the bioactive chemical in red seaweed which is known to have methane reduction capabilities. Any bolus based on bromoform would have to pass through the regulatory process, given bromoform can have carcinogenic effects.
Testing Bovaer
Prof Chris Reynolds of the Department of Animal Sciences, University of Reading, is a seasoned methane reduction researcher. “The amount of methane that a cow produces is determined primarily by how much feed she eats,” he says.
“For a given level of dry matter intake of feed, there is a certain amount of methane produced. We want to reduce the amount of methane that a cow produces when she eats her food.”
The Global Research Alliance on Agricultural Greenhouse Gases, comprising 68 member countries, published a review recently of several potential methane-reducing feed additives, looking at how well they worked, as well as the issues that might stand in the way of their adoption by industry.
“The three that came out as potentially the most effective were Bovaer, Asparagopsis seaweed and nitrate,” he says. “We did a study at the University of Reading where we fed Bovaer to animals for a 12-week period. We found that it reduced methane by over 30 per cent and that the effect was sustained through the feeding trial.”
Best breeding
Prof Richard Dewhurst, head of the Dairy Research Centre at Scotland’s Rural College is interested in using breeding to produce low methane-emitting ruminants; a process he acknowledges will never be a “quick fix”.
“In contrast to nutrition, where we have solutions like feed additives, genetic progress is much slower, perhaps one or two per cent per annum reductions, but it does have the advantage of being cumulative,” he says.
“We’re interested to identify cows that convert feed into milk and milk solids more efficiently ... So an animal that’s producing less methane for a given amount of feed is the one we’re looking for.
“One of the big advantages of using IVF is accelerating the rate at which we can use the genomic tools to breed for feed efficient and low methane emitting animals,” says Dewhurst. The first calves from this work are now being born.
This isn’t genetic modification, he underlines. “There is nothing GM about this. It’s regular breeding using tools to help us identify the elite animals in each cohort, and also reproductive tools to reduce the generation interval.”
Looking back over the many decades of selective breeding of dairy cows, the increases in milk production and composition show how over a long time you can have very large effects on the characteristics of farm animals, adds Dewhurst. “It’s all about making a start now breeding for reduced methane emissions.”
The Cool Cows project in the UK, of which he is part, is looking to accelerate the natural breeding process using selective sexing, where the sex of an animal is determined in advance and in-vitro fertilisation where the genetic benefits residing in a low methane emissions female can be matched with a low emitting male.
“Our first calves and this work are now being born, and you’ve probably seen or been involved in the publicity around Hilda, which was our first calf born from this programme,” says Dewhurst.
Targeting bacteria
Prof John Hammond, director of Research at the Perbright Institute in Surrey, England, says there is an opportunity to reduce methane emissions from ruminant fermentation by interfering with the bacteria in the rumen that produce the gas.
“We are looking to develop a vaccine that could work inside the cattle stomach, the rumen, to reduce the growth of methanogenic bacteria, the archaebacteria that produce the methane,” says Hammond.
“We are taking the reverse engineering approach, where instead of trying to design a vaccine, we are trying to find the antibodies that reduce methane growth. Once we understand that, we can generate a vaccine that can produce those kind of antibodies.”
Ireland faces a huge challenge if it is to comply with the 25 per cent reduction in agricultural greenhouse gas emissions by 2030 required under the Government’s climate action plan. To have a chance we need new strategies, such as the introduction of feed additives and breeding, says Waters.
The main obstacles in the way of bringing in new additives, says Waters, are that farmers are expected to pay for them without an obvious return, achieving regulatory approval and countering the kind of misinformation that led to the opposition that erupted in the UK before Christmas to the trial use of Bovaer in British dairy cows.
“The negative consumer reaction to Bovaer shows the need for scientists to have better communication and to build public trust in scientific advancements,” she says.
“We need to have policies introduced by Government to support the use of feed additives and ensure their widespread adoption. We can’t expect farmers to pay the extra cost for new additives if they are not seeing a return in terms of their income.”
However, Ireland is in a better position than some, to make the changes needed to meet our agricultural emissions targets. “Bovaer is registered for use in dairy cattle and the Irish Cattle Breeders Federation were the first internationally to develop breeding values – genetic evaluations – for reduced methane emissions,” says Waters.
