Can seaweed make cow burps less potent? These UC Davis scientists hope to find out

Early indications of a UC Davis study show feeding dairy cows seaweed may reduce methane emissions caused by their belching, the university announced Thursday.

UC Davis animal science professor Ermias Kebreab and animal biology PhD candidate Breanna Roque separated 12 Holstein cows into three groups, two of which received different doses of seaweed in their feed and one of which got no seaweed at all.

"The numbers we’re seeing are amazing — well beyond the target that farmers will need to reach," Kebreab said in a media release. "This is a very surprising and promising development."

The two test groups eat seaweed sweetened with molasses for two weeks at a time before returning to a normal diet for a week. Each cow eats a snack from an open-air device that simultaneously measures their breath's methane content. Their milk is also tested for yield, flavor and nutritional content throughout the experiment.

California lawmakers passed legislation in 2016 that forced owners of the state's 1.4 million dairy cows to cut methane emissions by 40 percent by 2030. Dairy farmers have experimented with greenhouse gas reduction techniques such as methane digesters in recent years in hopes of finding a cost-effective way to comply with the new regulations. Cows emit methane primarily through belching as well as defecation and flatulence.

“Results are not final, but so far we are seeing substantial emission reductions," Kebreab said. "This could help California’s dairy farmers meet new methane-emission standards and sustainably produce the dairy products we need to feed the world.”

An Australian lab found in 2016 that making seaweed two percent of a cow's feed could inhibiting gas-producing enzymes and cut methane emissions by 99 percent. The UC Davis experiment is the first to test the theory on live animals, according to the university.

Methane is 20 times more efficient at trapping heat in the atmosphere than carbon dioxide and accounted for 10 percent of the world's greenhouse gas emissions in 2016, according to U.S. Environmental Protection Agency data. Domestic animal digestion and defecation accounts for roughly 30 percent of all American methane production.

Preliminary results of Kebreab's study are expected to be released next month before further tests are conducted later in the summer.

Benjy Egel: (916) 321-1052, @BenjyEgel

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