Seaweed Shows Promise in Reducing Cattle's Climate Impact

Seaweed is once again demonstrating potential for enhancing the sustainability of cattle farming. A recent study conducted by researchers at the University of California, Davis, revealed that supplementing the diet of grazing beef cattle with seaweed pellets reduced methane emissions by nearly 40 %, with no impact on their health or weight. The findings were published in the journal Proceedings of the National Academy of Sciences.

This is the first study globally to test seaweed on grazing beef cattle. It builds on previous research that demonstrated seaweed reduced methane emissions by 82 % in feedlot cattle and more than 50 % in dairy cows.

How Much Methane Do Cattle Produce?

Livestock contributes 14.5 % of global greenhouse gas emissions, with the majority stemming from methane released by cattle when they burp. Grazing cattle emit more methane than feedlot cattle or dairy cows due to their higher fiber intake from grass. The US has 9 million dairy cows and more than 64 million beef cattle.

Beef cattle spend only about three months in feedlots and spend most of their lives grazing on pasture and producing methane. 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.

Ermias Kebreab, Study Senior Author and Professor, Department of Animal Science, University of California, Davis

Difficulty in Reducing Methane Emissions from Cattle

Kebreab explained that feeding pasture-based cattle is more challenging than feeding feedlots or dairy cows because they often graze far from ranches for extended periods. However, during winter or when grass is limited, ranchers typically supplement their diet.

For this study, researchers divided 24 beef steers (a mix of Angus and Wagyu breeds) into two groups: one group received the seaweed supplement, while the other did not. The 10-week experiment was conducted at a ranch in Dillon, Montana. Since the cattle were grazing, they consumed the supplement voluntarily, resulting in a nearly 40 % reduction in emissions.

Most research on reducing methane emissions through feed additives has been conducted in controlled environments with daily supplements. However, Kebreab noted in the study that fewer than half of these methods are effective for grazing cattle.

This method paves the way to make a seaweed supplement easily available to grazing animals. Ranchers could even introduce the seaweed through a lick block for their cattle.

Ermias Kebreab, Study Senior Author and Professor, Department of Animal Science, University of California, Davis

Kebreab stated that pastoral farming, which encompasses large grazing systems, supports millions of people worldwide, often in regions vulnerable to climate change. This study offers a way to make cattle grazing more environmentally friendly while contributing to the fight against climate change.

A related article in the same issue of PNAS highlights the importance of improving livestock production efficiency in low- and middle-income countries through better genetics, feeding, and health practices. The article’s author, UC Davis Professor and Cooperative Extension Specialist Alison Van Eenennaam, emphasized that this approach is the most promising way to meet global meat demand while minimizing greenhouse gas emissions.

UC Davis postdoctoral researchers Paulo de Méo Filho and John-Fredy Ramirez-Agudelo also contributed to the seaweed study.

The study was supported by Matador Ranch in Dillon, Montana.

Journal Reference:

Meo-Filho, P., et al. (2024) Mitigating methane emissions in grazing beef cattle with a seaweed-based feed additive: Implications for climate-smart agriculture. Proceedings of the National Academy of Sciences. doi.org/10.1073/pnas.2410863121.