Seaweed supplements can reduce methane in cattle by 82 per cent, new research claims

Meat is popular but it is very bad for the planet. Meat production uses around 82 per cent of the world’s farmland and produces 60 per cent of agriculture’s greenhouse gas emissions.

One of the key sources of greenhouse gases from beef production is methane. Belching cattle contribute this powerful gas over the course of their entire lifetime, and methane is 86 to 105 times more potent than carbon dioxide in terms of disrupting the climate over a 20-year period.

As a result, the heat is on for people to reduce their meat consumption, and to make meat production less ecologically destructive.

Now, scientists at the University of California, Davis have found that adding “a bit of seaweed” to cattle feed could reduce methane emissions from beef herds by as much as 82 per cent.

The researchers suggest their findings could “pave the way for the sustainable production of livestock throughout the world”.

“We now have sound evidence that seaweed in cattle diet is effective at reducing greenhouse gases and that the efficacy does not diminish over time,” said Ermias Kebreab, a professor at the university’s Department of Animal Science and director of the World Food Centre.

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PhD candidate Breanna Roque, who also worked on the study, said: “This could help farmers sustainably produce the beef and dairy products we need to feed the world.”

Last year Professor Kebreab and Ms Roque conducted the research by adding “scant amounts of seaweed” to the feed of 21 beef cattle and tracked their weight gain and methane emissions.

They found that cattle which consumed doses of about 80 grams of seaweed gained the same amount of weight as their herd mates, but burped out 82 per cent less methane into the atmosphere.

In the US, agriculture is responsible for 10 per cent of greenhouse gas emissions, and half of those come from cows and other ruminant animals which emit methane and other gases throughout the day as they digest food such as grass, hay, silage, soy and grains.

Professor Kebreab said: “Since much of livestock’s methane emissions come from the animal itself, nutrition plays a big role in finding solutions.”

In 2018, Professor Kebreab and Ms Roque were able to reduce methane emissions from dairy cows by over 50 per cent by supplementing their diet with seaweed for two weeks. This earlier research revealed that seaweed inhibits an enzyme in the cow’s digestive system which contributes to methane production.

In the new study they tested whether those reductions were sustainable over time by feeding cows seaweed every day for five months.

Four times a day, the cows ate a snack from an open-air contraption which measured the methane in their breath. Cattle only burp methane - the idea methane is released as flatulence is a common myth.

The scientists said their results were clear: Cattle that consumed seaweed emitted much less methane, and there was no drop-off in efficacy over time.

As a result the researchers said they are now looking at ways to farm the type of seaweed - Asparagopsis taxiformis - used in the tests, as there is not enough of it available in the wild for broad application.

And they are also looking at how they can provide seaweed supplements to grazing cattle on the open range.

“There is more work to be done, but we are very encouraged by these results,” Ms Roque said.

“We now have a clear answer to the question of whether seaweed supplements can sustainably reduce livestock methane emissions and its long term effectiveness.”

The research is published in the journal Plos One.