What happens when you feed seaweed to Angus and Wagyu cows?

Researchers at the University of California, Davis, have discovered that feeding grazing beef cattle a seaweed supplement can significantly reduce methane emissions without affecting the animals' health or weight. The study was published in the Proceedings of the National Academy of Sciences and authored by Paulo de Méo Filho, John-Fredy Ramirez-Agudelo, and Ermias Kebreab.

The researchers conducted the study over a 10-week period at Matador Ranch in Dillon, Montana. Science Daily reports they divided 24 young neutered male cattle, known as beef steers—a mix of Angus and Wagyu breeds—into two groups. One group received a seaweed supplement in pellet form, while the other group did not. The steers that ingested the seaweed supplement reduced their methane emissions by almost 40% compared to the control group.

The seaweed species used in the supplement was Asparagopsis taxiformis, which had previously been shown to reduce methane emissions by 82% in barn-raised beef cattle and over 50% in dairy cows. The study is the first to examine the effects of seaweed on grazing beef cattle.

Methane is a potent greenhouse gas, more than 28 times more effective than carbon dioxide at trapping heat in the atmosphere, according to Popular Science. Livestock is responsible for 14.5% of global greenhouse gas emissions, with the largest portion coming from methane gas released by cattle during digestion, particularly when they burp. Popular Science reports that 97 percent of all the methane gas from a cow is released by belching rather than farting, according to the United States Dairy Council and NASA.

Kebreab, a professor of animal science at the University of California, Davis, emphasized the importance of making feed additives accessible to grazing cattle. "We need to make this seaweed additive or any feed additive more accessible to grazing cattle to make cattle farming more sustainable while meeting the global demand for meat," Mirage News quotes him saying. He also pointed out that "beef cattle spend only about three months in feedlots and spend most of their lives grazing on pasture and producing methane."

Feeding pasture-based cattle is more challenging than feedlot or dairy cows because they often graze far from ranches for long periods. However, during the winter or when grass is scarce, ranchers often supplement the diet of grazing cattle. "Ranchers could even introduce the seaweed through a lick block for their cattle," Kebreab suggested.

The study measured the methane, carbon dioxide, and hydrogen emissions from the two groups of cattle. There was no significant difference in carbon dioxide emissions between the groups, but cows that did not receive the seaweed supplement emitted more hydrogen than those that did. The cows that received the supplement emitted an average of 115 grams of methane daily, which is 37.8% less than the 185 grams emitted by those without the supplement.

De Sevilla notes that this reduction in methane emissions could be a solution to decrease the contribution of the beef cattle sector to climate change. Livestock emissions, particularly methane from cattle, are a significant concern in efforts to combat global warming.

Alison Van Eenennaam, an animal geneticist at the University of California, Davis, highlighted the potential impact of the findings. "It is the most promising approach to meet the global demand for meat while limiting greenhouse gas emissions," Science Daily quotes her saying.

Pasture-raised beef cattle produce more methane because they eat more fiber from grass and tend to graze away from farms for longer periods.

Popular Science, El Economista, Diario de Sevilla, and Science Daily reported on the study, among other websites.

This article was written in collaboration with generative AI company Alchemiq