Seaweed extract cuts methane in grazing beef cows study finds

University of Adelaide researchers report that bromoform extract oil derived from the red seaweed Asparagopsis cut methane emissions in pregnant and lactating Angus cows by 49.5% to 77.0% during an eight-week trial in an extensive grazing system, with an average reduction of 60.6%. The peer-reviewed study, published March 20, 2026, in Frontiers in Animal Science, followed 21 cows and found no difference in cow body weight or calf body weight through 150 days post-calving, even though supplemented cows had lower dry matter intake. Adelaide highlighted the work on April 20, 2026, as evidence that methane-reducing supplementation may be feasible outside tightly controlled feedlot settings. (frontiersin.org)

Why it matters: For veterinary professionals working with beef herds, the study tackles a practical gap: whether methane-reduction strategies can work in breeding cattle on pasture, where intake is harder to control than in total mixed ration systems. The authors say no prior studies had assessed bromoform supplementation through late gestation and early lactation in an extensive system, and the lack of an observed growth penalty in calves will matter for herd health discussions with producers weighing sustainability goals against reproductive and performance risk. Still, the trial was small, and researchers noted mild metabolic alkalosis in a substantial share of cows, underscoring the need for continued monitoring as these products move closer to broader use. (frontiersin.org)

What to watch: Watch for larger field studies, residue and safety data, and whether grazing-system delivery can be standardized well enough for commercial adoption and, potentially, carbon-market or buyer-driven incentives. (axios.com)