Researchers at Adelaide University have found that a natural compound from seaweed can greatly cut methane emissions from beef cattle – and it doesn’t harm their calves.
The study tested bromoform extract oil, which comes from the red seaweed Asparagopsis. It was given to pregnant and breastfeeding Angus cows that were grazing freely on pasture. Seawood could be the answer to reducing methane emissions from cattle
Why this matters
Methane is a powerful greenhouse gas, responsible for around 30% of the rise in global temperatures since the Industrial Revolution. Cutting methane from grazing cattle is difficult because farmers can’t control their diet as closely as in feedlots. Finding practical solutions for grazing systems – where animals roam freely, and feed intake is less controlled – remains a significant challenge.
PhD student Kellie Wenham, from the School of Animal and Veterinary Sciences, said the results show strong potential for reducing emissions in real-world farming conditions.
“Across the eight-week trial involving 80 Angus cows, methane emissions were reduced by between 49% and 77 % in cows receiving the supplement,” Ms Wenham said.
What the study found
Over an eight‑week trial with 80 cows:
- Methane emissions dropped 49% to 77% in cows that received the seaweed compound.
- Calves were not harmed. They grew normally from birth to 150 days old.
- Cows stayed at a healthy weight even though they ate slightly less feed. This could save farmers money because productivity didn’t drop.
Health findings
- Some cows showed mild changes in blood chemistry, including mild metabolic alkalosis, but these were still within acceptable limits.
- Calves also had small changes in blood markers, but these were still normal.
Researchers say more work is needed to understand the long‑term health effects of seaweed supplements and to figure out the best dose and delivery method.
Why this study is important
Earlier research on bromoform was done in feedlots. This study shows it can also work in pasture-based systems, which are common in Australia.
What happens next
The team says the seaweed compound has real potential to help the livestock industry cut emissions – but farmers will only adopt it if it’s safe, practical, and affordable.
To read the full article, go to https://adelaide.edu.au/about/news/2026/seaweed-compound-shows-major-methane-cuts-in-beef-cattle-/
Published April 26th, Adelaide University News Seaweed compound shows major methane cuts in beef cattle
‘Efficacy of bromoform extract oil supplementation to mitigate methane emissions in Angus cows in an extensive system and the health impact on the cow-calf pair’ is published in Frontiers in Animal Science. DOI: 10.3389/fanim.2026.1789660
