DAVIS, Calif. – A new study by researchers at the University of California, Davis, found that feeding grazing beef cattle a seaweed supplement reduced their methane emissions by about 40 percent.

The research was inspired by the desire to reduce methane emissions from cattle, said Ermias Kebreab, associate dean and professor of the College of Agriculture and Environmental Sciences at UC Davis.

“We started looking at seaweed after in vitro (lab-based) experiments in Australia showed that one species (of seaweed) in particular was highly effective at reducing methane emissions,” he said.

An Australian company called Sea Forest produces a livestock supplement dubbed SeaFeed, an additive made up of Asparagopsis, a variety of red seaweed. The company claims that just 0.5 percent of SeaFeed can cut livestock methane production by up to 90 percent. In 2023, the company partnered with an Australian-owned restaurant to launch the world’s first low-emissions burger. Other partnerships include a fashion house that sells merino wool suits derived from sheep taking the supplement and an Australian premium marbled beef producer.

While the land down under might be racing to bring all cattle and sheep seaweed-supplemented feed, the additives produced in the U.S. still face FDA approval. For Kebreab’s study, seaweed pellets were sourced from Blue Ocean Barns, a company based in Hawaii. The pellets, called Brominata, are derived from a patented variety of Asparagopsis and satisfy the National Academies of Science, Engineering, and Medicine Daily Intake of iodine for cattle while providing eight essential amino acids.

Twenty-four grazing beef cattle, crossbreeds of Wagyu and Angus, were included in the study, which took place in Dillon, Mont. The cattle were split into two groups: those receiving the seaweed supplement and those not. Cattle receiving the seaweed supplement ate the additive voluntarily.

Kebreab admits that a challenge of the study was that the cattle didn’t find the additive palatable at higher doses, perhaps because it is salty. However, he said that the cattle were more likely to eat the supplement in lower doses, and the team has been working on enhancing the product’s palatability.

In addition to reducing methane emissions by about 40 percent, the seaweed supplement didn’t demonstrate any impact on the animals’ health or weight. Other studies have reported that the supplement can cause more favorable weight gain, Kebreab noted.

Previously, Kebreab and his team have found that seaweed supplementation in feedlot beef steers reduced methane emissions by 82 percent and over 50 percent in dairy cows.

But what about seaweed reduces methane emissions? Kebreab said it comes down to an active ingredient in the seaweed called bromoform. Bromoform prevents the chemical reaction needed for microbes to convert carbon dioxide and hydrogen into methane.

More research is underway to understand the efficacy of seaweed supplementation. Kebreab said his team is currently using it in a study to understand changes happening in the microbiome when methane is suppressed. Other researchers are working on longer-term studies to see if microbes that produce methane are undergoing adaptations that would lower the efficacy of seaweed additives. Additionally, researchers are interested in understanding if there are any health impacts when seaweed-supplemented beef is consumed by people.

Reducing methane emissions has been an important goal in agriculture for many years, with livestock accounting for 12 percent of global greenhouse gas emissions. Cattle are responsible for the largest portion of those emissions. As global demand for beef rises, understanding solutions to reduce increased methane emissions is critical.

“I think this is a viable solution,” Kebreab said. “Once we know the outcome of (additional studies), it will be ready for FDA approval.”

Kebreab said that he and his team will work with people interested in scaling up seaweed use and provide the science behind how it can be best used. The commercial implementation of seaweed supplementation will be left to start-up companies like Blue Ocean Barns.