Researchers from the University of California, Davis, along with collaborators from UC Berkeley and the Innovative Genomics Institute (IGI), have published a study that provides new insight into how red seaweed in cattle feed reduces methane emissions. The findings were released in the journal Microbiome.
Methane produced by cows is a significant greenhouse gas, with each cow releasing about 200 pounds annually. Methane has a much higher heat-trapping potential than carbon dioxide. Previous research at UC Davis demonstrated that adding red seaweed to cattle diets can significantly reduce methane emissions. However, the mechanisms by which this occurs were not fully understood until now.
The current study identified that red seaweed changes the activity of specific genes within the microbial community in a cow’s rumen, or gut. This change results in an increase in hydrogen production and the activation of certain bacteria capable of utilizing hydrogen. The researchers highlighted a bacterium from the genus Duodenibacillus that consumes hydrogen and converts it into succinate, a compound cows use to make protein.
“That’s important because too much hydrogen can lead to acidosis in the rumen, which can harm the animal,” said project leader and corresponding author Matthias Hess, a microbiologist and professor in the UC Davis Department of Animal Science and an IGI investigator. “Instead, this organism uses the hydrogen and converts it to succinate, a compound the animal can eventually use to make protein.”
Hess added that these discoveries could help develop communities of microbes that compete with methane-producing organisms for hydrogen.
“Hydrogen is a key energy source in the rumen, specifically for methane-producing microbes,” said principal investigator Spencer Diamond, with the IGI. “This study helps us better understand how other microbes that naturally occur in the rumen can divert this hydrogen away from methanogens and towards bacteria that may make animals more efficient.”
In their experiments, scientists took samples from eight cows—half received standard feed while half had red seaweed added for two weeks. Cows fed seaweed showed a 60% reduction in methane emissions, a 367% increase in hydrogen production, and up to 74% greater feed efficiency.
The team also reconstructed the genome of Duodenibacillus directly from rumen samples since it has not yet been isolated in laboratory conditions. Understanding its genetic makeup may inform future strategies for methane reduction without relying on additives like seaweed.
Authors of this study include Ermias Kebreab, Pedro Romero, and Breanna Roque of UC Davis; Pengfan Zhang of IGI at UC Berkeley; Nicole Shapiro and Emiley Eloe-Fadrosh from the U.S. Department of Energy Joint Genome Institute; as well as Matthias Hess and Ermias Kebreab as principal investigators at IGI.
Funding for this research came from several philanthropic organizations including Lyda Hill Philanthropies, Acton Family Giving, Valhalla Foundation, Hastings/Quillin Fund via Silicon Valley Community Foundation, CH Foundation, Laura and Gary Lauder and Family, Sea Grape Foundation, Emerson Collective, Mike Schroepfer and Erin Hoffman Family Fund through Silicon Valley Community Foundation, Anne Wojcicki Foundation via The Audacious Project at IGI; Shurl and Kay Curci Foundation; and support from the Office of Science at the U.S. Department of Energy.
