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Can seaweed help solve Ireland’s cow methane problem?

Ireland looks to seaweed to feed to cattle and sheep in quest to curb the methane they are breathing out.

Coleman Dundass, a seaweed harvester, ties up three "climin", two-tonne seaweed bundles he has gathered, as he stands in his currach boat in Kilkieran, Ireland. [Clodagh Kilcoyne/Reuters]
Published On 23 Nov 2021

Scientists are combing Ireland’s west coast for seaweed to feed to cattle and sheep after research showed it could stop them breathing out so much climate-warming methane.

The project, coordinated by a state agriculture body, is tapping into the country’s growing seaweed harvesting industry, which is seeking new markets as it revives centuries-old traditions.

But some are sceptical that the seaweed feed additives – or any quick technological fix – can sidestep the need to reverse a surge in Irish cattle numbers if the country is to reduce Europe’s largest per capita methane output by 2030.

About 20 species of seaweed, most from Ireland’s windswept Atlantic coast, have been tested by researchers while dozens more have been collected by the project’s partners in Norway, Canada, Sweden, Germany and the United Kingdom.

Scientists in the United States and Australia have already demonstrated dramatic methane-reducing qualities from one seaweed type – Asparagopsis – when small quantities are added to the feedstock.

But they have not yet managed to scale up production of the seaweed, which is not easy to grow in northwest Europe.

The Irish project aims to find abundant native seaweeds to use instead, even though the researchers admit they are unlikely to match the reduction in emissions of more than 80 percent shown with Asparagopsis.

Researchers are also working on how to integrate the feed additives into Ireland’s predominantly grass-based cattle farming system.

‘A huge market’

On a farm outside Hillsborough, southwest of Belfast, researchers use treats to coax cows to poke their heads into a solar-powered machine that measures the level of methane on their breath.

They will test them again using seaweed additives, said Sharon Huws, a professor of animal science and microbiology at Queen’s University Belfast.

“The levels that are used to feed ruminants are very, very small so you don’t need to get a lot of it in order to get an impact,” she said.

The Irish researchers have tapped into a network of seaweed harvesters who are reviving a tradition mentioned in monastic writings as far back as the 5th century.

But they do not yet have a plan to scale up production if tests are successful.

Some harvesters, who serve organic food and cosmetic markets, doubt the feed additives will be sufficiently lucrative with plenty of opportunities elsewhere.

“It’s a huge market at the moment, seaweed is really thriving,” said Evan Talty, the managing director at Wild Irish Seaweeds, who has revived harvesting techniques used by his grandfather and focuses on food and skincare products. The methane additive market is “not on our radar”, he said.

Others are more hopeful.

“Everyone keeps an eye on it,” said Jenny O’Halloran of Bláth na Mara, a small-scale hand harvester on Inis Mór island off Ireland’s west coast.

“Maybe the future of that is actually farming seaweed, which I think has to be part of the conversation when it comes to the future of seaweed in Ireland,” she said.

Sinead O'Brien, the founder of Mungo Murphy's Seaweed Company, holds up a piece of kelp (Laminaria) taken from a tank where abalone feed on it at her integrated multitrophic aquaculture farm where she grows the high-value abalone over a five-year period at her boutique business in Baile na hAbhann. "It's really important to have that sustainable cyclical relationship with the seaweed that's growing out there and using that natural feed for animals," said O'Brien. [Clodagh Kilcoyne/Reuters]
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Evan Talty, the managing director of Wild Irish Seaweeds, turns the Carrigeen Moss (Chondrus crispus) seaweed in a field on his seaweed farm where it has been laid out to dry in the sun, in the County Clare village of Quilty. "Sustainably harvesting means that we get crop regeneration. Seaweed has been harvested in this area for hundreds of years, once sustainably harvested in the same way as our ancestors have done, it will continue to regenerate," said Talty. [Clodagh Kilcoyne/Reuters]
David O'Halloran, who runs the seaweed company Blath na Mara with his wife Jenny O'Halloran, harvests Sea Spaghetti seaweed (Himonthalia elongata) on a rocky shore on Inis Mor of the Aran Islands. [Clodagh Kilcoyne/Reuters]
Steven Morrison, programme leader in Sustainable Livestock Production at AFBI (Agri-Food and Biosciences Institute) in Northern Ireland, and professor of Animal Science and Microbiology Sharon Huws at Queens University Belfast, in front of dairy cattle at the Agri-Food and Biosciences Institute research farm in Hillsborough. The dairy cattle are participating in a trial of being fed seaweed to offset methane emissions. "From having an understanding of what the animals are producing, we then can look at mitigation options - how can we alter diets, how can we look at genetics of the animals, how can we really drive those greenhouse gas emissions down," said Morrison. [Clodagh Kilcoyne/Reuters]
Dairy cattle that are participating in a trial of being fed seaweed to offset methane emissions gather around the solar-powered methane measuring machine at the AFBI research farm in Hillsborough. [Clodagh Kilcoyne/Reuters]
Sheep stand together in the Teagasc Agriculture and Food Development Authority in its Mellows Campus in Athenry. [Clodagh Kilcoyne/Reuters]
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Emily Roskam, a PhD Walsh Scholar at Teagasc, feeds sheep during a Seasolutions trial where sheep are fed seaweed extract to reduce their methane emissions at the Teagasc Agriculture and Food Development Authority in its Mellows Campus in Athenry. "Research has shown that different seaweeds reduce methane emissions, there's green, brown and red seaweed, these (in the trial) are a brown seaweed extract and we are seeing if they reduce methane emissions in the sheep," said Roskam. [Clodagh Kilcoyne/Reuters]
Emily Roskam lets a sheep out of a methane measuring chamber, after measuring its methane emissions at the end of a Seasolutions trial. "We have 140 sheep here and each morning they are getting half a kilo of concentrates, they get 400 grams of nuts made of maize meal and a bit of molasses which is kind of sugary to stick them together, then they each get 100 grams of their additives, we have a 'control diet' or we have seaweed extract." [Clodagh Kilcoyne/Reuters]
David O'Halloran, who runs the seaweed company Blath na Mara with his wife Jenny O'Halloran, works with seaweed harvester Marc O'Goill to take down fully dried Kombu (Laminaria digitata) which hangs in the drying room on the O'Halloran's seaweed farm before packing it into a giant sack. "Because of the nature of seaweed and the market it's in, all of the customers and clients really see the environment as an important part of their lives as well, so it's important to the customers and it's important to us that it's environmentally sustainable," said O'Halloran. [Clodagh Kilcoyne/Reuters]
David O'Halloran picks up a pot of seaweed pesto he has made with his wife Jenny as part of a line of products that their seaweed company Blath na Mara sells using seaweed that they have harvested. [Clodagh Kilcoyne/Reuters]