By Ruth Milka
Quick summary:
• Feeding grazing cattle a seaweed supplement reduced methane emissions by nearly 40 percent without affecting their health or weight.
• Methane is a potent greenhouse gas, and livestock accounts for 14.5 percent of global emissions, with cattle being a major contributor.
• Grazing cattle produce more methane due to their high-fiber grass diet compared to feedlot or dairy cows.
• The UC Davis study is the first to test seaweed supplements on grazing beef cattle and was conducted over 10 weeks on a Montana ranch.
• Seaweed can be introduced through lick blocks or pellets, making it more accessible for grazing cattle.
• The findings offer a potential solution to reduce methane while supporting sustainable farming practices globally.
• Scaling seaweed production and reducing costs are key challenges for widespread adoption.
A new study led by researchers at the University of California, Davis (UC Davis), has unveiled a promising solution to one of agriculture’s largest environmental challenges: methane emissions from cattle. The study, published in Proceedings of the National Academy of Sciences, found that feeding grazing beef cattle a seaweed supplement in pellet form reduced their methane emissions by nearly 40 percent. These findings hold significant potential for making cattle farming more sustainable while addressing the urgent need to combat climate change.
Methane, primarily released through cattle burps, is a potent greenhouse gas with a warming potential far greater than carbon dioxide. Livestock alone accounts for approximately 14.5 percent of global greenhouse gas emissions, with methane being the largest contributor. Grazing cattle, which consume a high-fiber grass diet, produce even more methane than feedlot or dairy cows. In the United States alone, there are over 64 million beef cattle and 9 million dairy cows, illustrating the scale of the problem.
The UC Davis study is the first of its kind to evaluate seaweed’s methane-reduction potential in grazing beef cattle. Previous research focused on controlled environments showed that seaweed supplements reduced methane emissions by over 50 percent in dairy cows and by as much as 82 percent in feedlot cattle. However, because beef cattle spend most of their lives grazing on pasture, addressing their emissions presents unique challenges.
“Beef cattle spend only about three months in feedlots and spend most of their lives grazing on pasture and producing methane,” said Ermias Kebreab, senior author of the study and a professor in the Department of Animal Science at UC Davis. “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.”
Conducted at a ranch in Dillon, Montana, the study involved 24 beef steers, a mix of Wagyu and Angus breeds, divided into two groups. One group received a seaweed supplement (pelleted Asparagopsis taxiformis), while the other did not. The 10-week experiment revealed that the steers consuming the supplement voluntarily reduced their methane emissions by an average of 37.7 percent without any negative impact on their health or weight.
“This study suggests that the addition of pelleted bromoform-containing seaweed (Asparagopsis taxiformis) to the diet of grazing beef cattle can potentially reduce enteric methane (CH4) emissions (g/d) by an average of 37.7 percent without adversely impacting animal performance,” the study authors noted. This research marks a critical step forward because most previous methane-reduction studies relied on daily feed additives in controlled environments, which are not practical for grazing cattle.
Unlike feedlot or dairy cattle, grazing beef cattle often roam far from ranches for extended periods, making daily supplementation difficult. Kebreab acknowledged this logistical challenge but suggested potential solutions, such as introducing seaweed supplements through lick blocks, which grazing cattle could access at their convenience.
“This method paves the way to make a seaweed supplement easily available to grazing animals,” Kebreab said. “Ranchers could even introduce the seaweed through a lick block for their cattle.”
Reducing methane emissions from livestock is essential to mitigating climate change, as methane traps heat in the atmosphere much more effectively than carbon dioxide. Short-lived but highly potent, methane contributes significantly to global warming, making livestock a major target for climate solutions.
Millions of people worldwide depend on pastoral farming, particularly in low- and middle-income countries where large grazing systems are common. These areas are often highly vulnerable to the effects of climate change, such as drought and extreme weather. The UC Davis study presents a way to make cattle farming more sustainable, potentially offering economic and environmental benefits to these communities.
“The findings may be relevant in the context of growing global demand for livestock products and the urgent need to address the environmental impacts of animal source foods,” the study stated. “Thus, this study contributes to the broader efforts aimed at developing more sustainable and environmentally friendly agricultural practices.”
While the study’s results are promising, significant barriers remain to scaling the use of seaweed supplements in cattle farming. Seaweed production must increase dramatically to meet the demand, and the cost of supplements must be reduced to ensure they are accessible to ranchers globally. Researchers also need to study the long-term effects of seaweed supplementation on cattle health, productivity, and ecosystems.
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