San Francisco Chronicle - (Sunday)
Seaweed feed relieves gassy cow burps
Small amount has big impact on climate, says UC Davis team
Beef and dairy production are considered important drivers of climate change, contributing roughly 5% of U.S. greenhouse gas emissions, mostly in the form of methane released by cattle and other ruminant animals. But adding just a small amount of seaweed to cattle feed can reduce the output of methane in their burps by 82%, a UC Davis study published Wednesday concludes.
“We have a billion cattle in the world, and if even a few of them get it, it will make a big difference,” said Ermias Kebreab, coauthor of the study and an animal science professor at UC Davis. Kebreab and graduate student Breanna Roque added a dried and powdered seaweed supplement to beef cattle’s feed over five months. The seaweed inhibits an enzyme in the cow’s digestive system that contributes to methane production in the form of burps.
Kebreab published a similar study using dairy cattle in 2019 that showed a 50% reduction in methane in cow burps, while the new one showed a larger impact and demonstrated that it can be sustained over a cow’s lifetime, he said. Neither the cattle’s beef nor milk took on the flavor of seaweed in either study.
California, the largest dairy state in the nation, has the country’s most ambitious goals for reducing greenhouse gas emissions, with an official state target of cutting them 40% below 1990 levels by 2030 and 80% by 2050. The state also has a separate goal to reduce methane and other shortlived climate pollutants by 40%, which puts particular pressure on dairy and beef farmers. But Kebreab said there was plenty of interest from other countries and industry in improving animal agriculture’s climate scorecard.
The limiting factor is that the strain of seaweed used in the study, a red algae called Asparagopsis taxiformis found to be the best type for reducing methane, isn’t common enough to feed all the world’s cattle. Blue Ocean Barns on Hawaii’s Big Island is among a handful of companies in the world that cultivate the algae, and it plans to have enough to feed 5 million cows by mid2025. It grows the seaweed on land in tall tanks using fresh ocean water, where the algae blooms into large fernlike tendrils.
The company, which provided the seaweed for the UC Davis study and also contributed financial support for the research, is partnering with Straus Family Creamery in Marin County for its first commercial trial of the seaweed supplement this summer.
“We are targeting California as a market that is extremely large — the largest dairy state in the nation — and also one where the farm families are committed to both sustainable and high productivity of their animals,” said Joan Salwen, CEO of Blue Ocean Barns, which is also partnering with multinational companies on upcoming pilot programs.
Methane is 25 times more effective at retaining heat than carbon dioxide but only stays in the Earth’s atmosphere for 12 years, whereas carbon dioxide can remain for thousands of years. Reducing methane can therefore have a cooling effect, Kebreab said.
If every cow on Earth received the seaweed supplement for a year, it could reduce emissions by roughly 1,075 million metric tons of carbon equivalent, which is about double the entire greenhouse gas emissions from California or about 15% of the entire U.S. output.
During the UC Davis study, Kebreab’s lab fed 21 beef cattle feed laced with seaweed powder while their heads were inside a machine that measured the amount of methane in their breath. The researchers wanted to learn if the microbes in their guts would adapt to the seaweed over time, but the seaweed didn’t lose its effectiveness.
The researchers started with young animals so they could see how it worked with the different feed they get at different stages of their life cycle. When the animals were fed more hay, the team added molasses to help the seaweed stick so the cows couldn’t nudge it aside.
“Cows are really good at sorting things they don’t like to eat,” Kebreab said.
But the algaeeating cattle didn’t seem to have issues with the flavor because they didn’t lose weight compared to cattle fed a seaweedfree diet.
The next challenge is finding the best way to use it with cows that are grazing on land, Kebreab said.
Although 45% of the state’s methane output on dairy farms comes in the form of cow burps, according to UC Davis, it also gets released in manure. That can be put into digesters that convert the gas into energy, which some California dairy farmers have done with state funding, including Albert Straus of Straus Family Creamery. His home farm is totally powered by electricity from its digester, and he is working on a program to make digesters more affordable to small farmers and to give them an income stream from carbon credits.
“I’m trying to create this model that not only can be replicated throughout the county but throughout the world,” Straus said. “The goal is to show that farms can be beneficial to the environment and the planet and create a food system that is local.” Though many recommend avoiding or reducing meat or dairy consumption as the best way to lower greenhouse gas emissions from agriculture, Kebreab said the growing demand for dairy and beef in the developing world and the relatively small amount of land suitable for row crops globally make animal agriculture a vital nutrient source.
“Grazing land is more available than crop land. (Animals) use marginal land,” he said. “It’s really important for livestock to make food out of it. We can’t really do anything with grasses.”