Seaweed Supplement Cuts Methane Emissions From Cows

A new study found that seaweed in cattle feed could slash methane emissions by as much as 82%.

This steer at UC Davis was fed a small amount of seaweed that resulted in a dramatic drop in methane emissions. (Photo by Breanna Roque/UC Davis)

(CN) — An earth-friendly burger may be able to contain beef after all.

Researchers at the University of California, Davis, found that a little seaweed in cattle feed could slash methane emissions by as much as 82%.

The results could revolutionize the globally sustainable production of livestock, according to a study published Wednesday in the journal PLOS ONE.

“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, an associate dean in the UC Davis College of Agricultural and Environmental Sciences and the director of the World Food Center

Building on their earlier work with dairy cattle, Kebreab and doctoral student Breanna Roque spent last summer tracking 21 beef cattle after adding “scant amounts of seaweed” to the animals’ diet. The seaweed inhibits an enzyme in the cow’s digestive system that contributes to methane production.

The results surprised them. Cattle that consumed three ounces of seaweed gained as much weight as their herd mates while drastically cutting the amount of methane they burp into the atmosphere.

Methane is one of many greenhouse gases that contribute to climate change. Half of the greenhouse gas emissions from U.S. agriculture come from cows that release as they digest grass and hay, leading some to suggest people should eat less meat to reduce global warming.

Kebreab is not among those criticizing the cultivation of beef cattle. He prefers to see them as nutrition generators.

“Only a tiny fraction of the earth is fit for crop production,” Kebreab explained. “Much more land is suitable only for grazing, so livestock plays a vital role in feeding the 10 billion people who will soon inhabit the planet.”

To counter methane emissions, Kebreab instead is looking to dietary changes to find solutions that reduce methane.

“This could help farmers sustainably produce the beef and dairy products we need to feed the world,” added Roque.

Kebreab and Roque collaborated with a federal scientific agency in Australia called the Commonwealth Scientific and Industrial Research Organization, James Cook University in Australia, Meat and Livestock Australia, and Blue Ocean Barns, a startup company that sources, processes, markets and certifies seaweed-based additives to cattle feed. Kebreab is a scientific adviser to Blue Ocean Barns.

In 2018, Kebreab and Roque cut methane emissions from dairy cows in half by adding seaweed to their diet.

In the new study, researchers tested whether such reductions were sustainable by feeding cows seaweed daily for five months through an open-air device that measured the methane in their breath.

The results could not have been more promising. Cattle that ate seaweed emitted much less methane, with no drop-off in efficacy over time.

Equally important, a panel of tasters found no difference in the flavor of beef from steers that were fed seaweed, much the same way that similar tests found no change in the flavor of milk from dairy cows fed seaweed.

The study represents new challenges, however. Asparagopsis taxiformis, the type of seaweed used in the tests, does not exist naturally in sufficient quantities to feed millions of cows. Likewise, researchers don’t know how ranchers could provide seaweed supplements to free-range cattle.

So for Kebreab and Roque, the work continues.

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

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