A seaweed diet could eliminate most of cows’ greenhouse emissions

Seaweed never ceases to surprise me.

Besides making peanut butter more spreadable, providing carbon offsets to fight climate change, and being a rising star in the alt protein movement (along with edible insects) — feeding seaweed to cows can make them belch less. Why does that matter? Because cow burps contribute to climate change.

“We now have sound evidence that seaweed in cattle diet is effective at reducing greenhouse gases,” UC Davis ecologist Ermias Kebreab told Capital Press.

Cows produce several greenhouse gases. But methane emissions are the most dangerous byproduct of their digestive tracts. Even though we’ve all grown accustomed to attributing carbon dioxide to climate change, methane is a stronger greenhouse gas and can trap more heat in the atmosphere than carbon dioxide. According to the EPA, methane is responsible for 10% of all U.S. greenhouse emissions, second only to CO2.

Kebreab’s team at UC Davis thought that seaweed would lower the methane cows emit by inhibiting an enzyme in the cow’s digestive system.

Last summer, Kebreab and Breanna Roque, a UC Davis animal biologist, fed 21 cattle a small amount of seaweed and monitored their weight gain and methane emissions for five months. They tracked the cow emissions using a particular type of breathalyzer. Instead of sensing alcohol, it smelled methane, which they measured several times a day.

They discovered that feeding cows just a touch of seaweed dramatically lowered the amount of methane they, uh, released.

The results, published in PLOS ONE, showed that three ounces of seaweed added to their diet eliminated most of cows’ methane emissions, while still allowing them to put on the same amount of weight.

“So, in our dairy study, we found up to a 67% reduction in methane,” Roque told NBC Bay Area. She also found that feeding the ocean salad to cows bred for beef led to an 82% reduction in methane.

According to the Associated Press, cattle account for more than 70% of livestock emissions. And Giampiero Grossi, an ecologist at Tuscia University in Italy, says that methane emissions generated by ruminant livestock account for around 5.5% of all greenhouse gasses produced by human activity.

“Livestock plays a vital role in feeding the 10 billion people who will soon inhabit the planet. Since much of livestock’s methane emissions come from the animal itself, nutrition plays a big role in finding solutions,” Kebreab said in a statement.

The team also did a taste comparison between the steak from a seaweed-fed cow and a traditional steak. (Because, why not — fighting climate change shouldn’t taste any less savory, right?)

“We had 112 people tasting the beef and they could not detect any difference in taste,” Kebreab said.

But fossil fuels still reign when it comes to global warming. Carbon dioxide, despite being a weaker greenhouse gas, is produced in vastly greater quantities than methane — accounting for 80% of all greenhouse emissions in the U.S., according to the EPA and while methane is potent in the short-run, it doesn’t stay in the atmosphere as long.

Eventually, natural processes eliminate it, while CO2 can remain in the atmosphere for years. But seaweed is cheap, and feeding it to cows could have a relatively large impact — potentially setting a new standard for sustainable livestock production.

“This has a huge implication for the dairy industry because the state has a mandate to reduce methane emissions by 40% in the next nine years,” Kebreab said.

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