Scientists Say Feeding Cows Seaweed Could Cut Their Methane Emissions 82 Percent

By Joseph Guzman, The Hill

18 March 21

Agriculture makes up about 10 percent of emissions in the U.S.

eeding cattle just a tiny bit of seaweed each day could help the agriculture industry significantly cut back on greenhouse gas emissions.

Agriculture makes up about 10 percent of emissions in the U.S., with about half of that portion coming from cattle that belch and release methane, a potent greenhouse gas, and other gases as they digest grass and hay.

While that has led to a push by conservationists to urge people to eat less meat to help reduce emissions, scientists from the University of California, Davis focused on animal nutrition to try and find a solution.

Researchers behind a study published in PLOS ONE this week added small amounts of seaweed to the diet of 21 beef cattle over the duration of five months and tracked their methane emissions and weight gain. The cows ate from an open-air container that measured the methane in their breath four times a day.

The study found cattle that consumed 3 ounces of seaweed daily gained as much as their herd mates and released 82 percent less methane into the atmosphere.

“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,” Ermias Kebreab, director of the World Food Center and agricultural scientists at University of California, Davis, said.

A type of seaweed called Asparagopsis taxiformis counteracts emissions from cows by inhibiting an enzyme in the animal’s digestive system that contributes to the production of methane.

Separate research from Kebreab and his Ph.D. graduate student Breanna Roque in 2018 found a 50 percent drop in emissions from dairy cows who were fed seaweed for just two weeks. A taste test also found no differences in the flavor of beef or milk from seaweed-fed steers.

Researchers note there is currently not enough of the seaweed available in the wild for broad use and are looking into ways farmers could produce the seaweed on a large scale.

“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.”