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.