How Scary are Cow Burps?

Very! But seaweed looks like it's set to be a planet-saving, anti-burping drug for cows.

How scary are cow burps exactly? Measured by their planet-warming power, methane-filled livestock belches are the equivalent of 850 coal plants burning year-round. Estimates vary, but livestock are reckoned to be responsible for up to 14% of all greenhouse emissions and methane, belched out by ruminants, accounts for more than a third of the total emissions from agriculture. Hardly surprising, when you discover that the average ruminant produces 250-500 litres of methane a day.

But the good news is that scientists have found that spicing up cattle feed with a little seaweed can dramatically reduce the methane they produce.

The evidence on a tropical red seaweed, Asparagopsis taxiformis, keeps getting stronger. Scientists began studying the effects of putting seaweed in cow feed in 2005, and as the experiments have moved out of the lab and into the barn, the promising results held up. The latest study, published in the journal PLoS One, shows that when beef cattle ate a little bit of seaweed - a small handfull - mixed in with their feed each day, they burped out 82 percent less methane.

That's the equivalent of closing down 697 coal-fired power stations. To put that into perspective, that's the equivalent of shutting 60 percent of China's coal plants, or all of the USA's (three times over).

“This is much more than I expected, to be honest,” said Ermias Kebreab, an animal scientist who studies greenhouse gas emissions at the University of California, Davis. “I didn’t think we would get 80 percent reduction - that’s absolutely huge.”

In further good news, another study in 2019, funded by the US government, got similar results with dairy cows.

So how long until farmers start putting seaweed into their feed? There are still two major hurdles. The Food and Drug Administration classifies feed additives as drugs, so scientists need to complete clinical trials on cattle eating seaweed, which Kebreab said are already underway. Companies also need to figure out how to grow this red seaweed efficiently enough to provide it at a low cost.