CLEAR Conversations: UC Davis Researcher Explores New Tools to Reduce Livestock Methane
In this episode of CLEAR Conversations, researcher, professor and director of the World Food Center, Ermias Kebreab discussed his research on methane reduction strategies in livestock production—work that has helped position UC Davis as a global leader in agricultural sustainability research.
“I work in the intersection of livestock productivity and environment,” Kebreab explained. “Trying to increase livestock productivity and have more sustainable livestock production systems, while at the same time reducing impacts on the environment.”
Much of Kebreab’s work focuses on methane, a potent greenhouse gas produced naturally during digestion in cattle and other ruminant animals. While methane remains in the atmosphere for a shorter period than carbon dioxide, it has a much stronger warming effect in the near term.
“Methane is a short-lived climate pollutant,” Kebreab said. “Reducing methane gives us a quicker way to help limit the impacts of climate change.”
That urgency has fueled more than a decade of research into practical methane mitigation strategies for dairy and beef cattle. Among the most widely recognized is Kebreab’s work with seaweed feed additives. The research began after scientists in Australia identified a species of red seaweed, Asparagopsis, that showed strong potential to reduce methane formation in laboratory studies. Working with collaborators and industry partners in California, Kebreab’s team tested whether the seaweed could work under real feeding conditions in cattle.
The results surprised even him.
“We saw a very high level of methane reduction with a very small amount of seaweed,” he said.
Early studies demonstrated methane reductions approaching 80% in some cattle trials. More recently, researchers have explored oil-based formulations derived from seaweed compounds, which may improve feed palatability while maintaining methane reductions.
“We’re seeing that productivity may even improve,” Kebreab said. “And the animals are quite happy to consume it when it’s mixed well in the feed.”
But the research extends far beyond a single feed additive. Kebreab’s lab also synthesizes global methane mitigation data to help producers and policymakers better understand which strategies work under different conditions.
Through large-scale reviews of studies conducted around the world, his team evaluates approaches including seaweed, 3-NOP, tannins, and other feed additives aimed at reducing methane emissions in livestock systems.
“The idea is to make the information practical,” he explained. “If producers want to know what level of reduction they might achieve under certain feeding conditions, we can help provide recommendations based on the available data.”
Some of the most innovative research has focused on agricultural byproducts already abundant in California. One project examined grape pomace—the skins, seeds, and stems left over from wine production—as a feed ingredient for dairy cattle. Rich in tannins and other plant compounds, grape pomace offered an opportunity to reduce waste while potentially improving animal performance. The cows appeared to enjoy it.
“They were happily consuming quite a lot of the grape pomace,” Kebreab said.
The results showed modest methane reductions, improved feed efficiency, and increases in beneficial fatty acids in milk. Similar work is now exploring olive pomace and fermented almond hulls as potential feed ingredients. The approach reflects a broader goal of creating more circular agricultural systems by repurposing byproducts that might otherwise go unused.
“We’re really trying to utilize whatever byproducts we have and upcycle those nutrients,” Kebreab said.
Another area of research explores whether methane production can be influenced early in an animal’s life. Kebreab’s team is studying whether feeding methane-reducing supplements to calves shortly after birth can alter the development of microbes in the rumen—the specialized stomach chamber where methane-producing microorganisms thrive.
Working with collaborators at UC Berkeley and UC Davis, researchers are tracking how the microbiome develops over time and whether early interventions can create longer-lasting methane reductions.
“We’re trying to understand the mechanisms behind these changes,” Kebreab said.
The research also includes investigations into CRISPR and microbial gene editing technologies aimed at redirecting hydrogen within the rumen away from methane production and toward more efficient energy pathways. The goal is ambitious: reduce methane while improving productivity at the same time. While the science continues to evolve, Kebreab emphasized that collaboration with producers remains central to the work. California dairy farmers, he said, have shown strong interest in sustainability solutions and are actively partnering in research trials.
“They are very open to working with us,” he said. “They want practical solutions that make sense economically and environmentally.”
That collaboration between researchers, producers, policymakers, and industry leaders is one reason Kebreab values events like the CLEAR Center’s State of the Science Summit, where conversations around methane mitigation continue to grow.
“It takes a village to move this forward,” he said. “Science is one part of a much larger effort.”
As he has at previous Summits, Kebreab will participate in several panel discussions as part of this year's robust agenda. For him, one of the most encouraging developments is seeing research begin to move from laboratory studies and research into real-world adoption offers optimism for the future.
“I see the work starting to translate into practice,” he said. “That makes me hopeful.”