Cows that eat red seaweed as part of their diets release up to 82% less methane than their bovine peers, according to a new study by researchers at the University of California.
The team incorporated a small, medium, or large amount of red seaweed into the diets of 21 “Angus-Hereford beef bullocks” and measured how much methane, hydrogen, and carbon dioxide (CO2) they released via burps and farts over a 21-week period. Cows with a little or moderate amount of seaweed released 45% to 60% less methane than other cows, while those with a lot of seaweed in their diet released up to 82% less methane.
While methane doesn’t linger in the atmosphere as long as CO2, it's at least 30 times more effective at trapping heat from the sun. As a result, the United Nations reports that it’s imperative for countries to combat sources of methane.
The scientists behind the study said that when beef from the seaweed-eating cows was prepared and cooked, it tasted no different than standard beef. They added that seaweed has the bonus benefit of reducing the cost of beef production.
“These feed cost reductions in combination with significantly reduced methane emissions have a potential to transform beef production into a more economically and environmentally sustainable red meat industry,” said the study, which was published in the journal PLoS ONE.
Bringing this new diet to scale will require significant investments in aquaculture, the study reports, because there’s currently not enough seaweed farmed worldwide. The scientists recommend local production of seaweed to cut down on transportation costs.
In addition to reducing methane emissions, growing seaweed would also create carbon sinks that pull CO2 from the atmosphere.
"There is more work to be done, but we are very encouraged by these results," Breanna Roque, an author of the report, said in a press release. "We now have a clear answer to the question of whether seaweed supplements can sustainably reduce livestock methane emissions and its long-term effectiveness."
Climate scientists have been urging people to eat less red meat because beef production is a leading source of greenhouse gas emissions like methane. In the US, beef production is responsible for 10% greenhouse gas emissions annually.
There are other reasons to avoid red meat, according to advocates. Factory models of animal production torture animals; pollute water, soil, and air; use crops that could otherwise feed people; and drive deforestation.
But as food production evolves in the years ahead, this new study shows that the ongoing production of beef can be made less harmful by diversifying cow diets.