How far are we from cutting cattle methane with seaweed feed?
Small amounts of the red seaweed Asparagopsis taxiformis, added to cattle feed, cut methane in a feedlot-style steer trial. The size of the cut depended on dose and diet. Bromoform, the compound behind the effect, still needs work on residues in milk and effects on the rumen. The sources we could open report no approval for an Asparagopsis feed additive in the EU, the US, Australia or New Zealand. Commercial supply is at pilot scale.
Close. Early pilots are running in the real world.
Trials have measured lower methane in steers, and pilot farms are growing the seaweed. Publicly disclosed site capacities are in the tens to low hundreds of tonnes a year. Milk residues and rumen effects are not settled, no regulator approval for an Asparagopsis feed additive was found in the markets checked, and the evidence so far comes from small trials. That matches pilot, not scaling: the technology works in trials, but it has not yet been cleared for routine use in the main markets.
The tech tree
Everything recorded on Vrulum that this future needs, oldest foundations at the top and the goal at the bottom. Lines show what each step requires.
- 2021Methane cut in a feedlot-style steer trialDone Unlocked.
- 2024Benchmark: 3-NOP (Bovaer) cleared for dairy cattleDone Unlocked.
- 2025Safety assessment for consumers and animalsIn progress Being researched.
- 2026Commercial seaweed production for feedIn progress Being researched.
- Date not recordedFeed additive approval for AsparagopsisNot started Locked.
- Date not recordedCommercial sales to beef and dairy supply chainsNot started Locked.
- Date not recordedMethane effect shown to last over a full production cycleIn progress Being researched.
- GoalCutting cattle methane with seaweed feedGoalRequires: Seaweed farming at scale, Methane cut in a feedlot-style steer trial, Safety assessment for consumers and animals, Feed additive approval for Asparagopsis, Commercial seaweed production for feed, Commercial sales to beef and dairy supply chains, Methane effect shown to last over a full production cycle, Benchmark: 3-NOP (Bovaer) cleared for dairy cattle. Locked.
The road so far
2 of 7 steps done, 3 in progress.
- Done · Mar 2021Methane cut in a feedlot-style steer trial
In a 147-day study, 21 Angus-Hereford steers were allocated to control, 0.25% and 0.5% Asparagopsis taxiformis. One steer was removed after an injury, leaving 7 control, 7 low-dose and 6 high-dose steers. Methane yield fell 45% at the low dose and 68% at the high dose overall, and 80% at the high dose on a low-forage diet. Dry matter intake fell 14% at the high dose, and average daily gain did not differ. The authors say the small groups need further study and call for a larger feedlot trial. [1]
- In progress · Oct 2025Safety assessment for consumers and animals
A 2023 review by Eason and Fennessy concludes that bromoform given at very low doses is not bioavailable at measurable levels, and that the risk of residue transfer or toxicity in livestock and humans will be minimal. A 2025 advisory opinion from the Dutch BuRO takes a more cautious view. It says no safe maximum bromoform level in feed can currently be set, that feed levels cannot yet be fixed to keep milk within the safe limit, and that current legislation sets no legal limit for bromoform in feed or animal products. BuRO gives 232 µg/L as the maximum for cow's milk and cites 35 µg/L as the highest reported level in the literature. [2][3]
- Not startedFeed additive approval for Asparagopsis
The sources we could open report no approval decision for an Asparagopsis feed additive in the EU, the US, Australia or New Zealand. The status of any pending application could not be confirmed from those sources. [2][3]
- In progress · Jul 2026Commercial seaweed production for feed
Fremantle Seaweed licensed FutureFeed's intellectual property in July 2026. The Rural describes this as the step needed to sell an Asparagopsis supplement commercially. The company projects up to 576 tonnes a year across its first two ocean leases, a 32-hectare pilot farm and a proposed 160-hectare lease. The article says publicly disclosed site capacities are in the tens to low hundreds of tonnes a year, and that Australia publishes no consolidated national production figure. [7]
- Not startedCommercial sales to beef and dairy supply chains
Fremantle Seaweed's October 2026 purchase of FutureFeed nursery and production assets brings its first commercial sales target forward to 2027, according to IT Brief. The article gives no price or volume for the purchase or for those sales. [8]
- In progressMethane effect shown to last over a full production cycle
The feedlot trial ran for 147 days, and its authors say a larger feedlot trial is needed to reduce animal variability. Whether the methane effect holds across a full production cycle is not shown in the sources we could open. [1]
- Done · 28 May 2024Benchmark: 3-NOP (Bovaer) cleared for dairy cattle
3-NOP is a different, synthetic compound. Elanco announced on 28 May 2024 that the US FDA had completed its review and found it met safety and efficacy requirements for lactating dairy cattle. Elanco says feeding it can reduce methane emissions about 30%, and that it is already available in Canada and Mexico for beef and dairy cattle. The EFSA found it safe for dairy cows at 100 mg/kg dry matter in 2021, and it could not conclude on safety for other animal categories. The EU Joint Research Centre page lists Commission Implementing Regulation (EU) 2022/565 as the recommended method for EU control. The benchmark shows that a feed additive can reach regulatory approval in dairy cattle, but it does not show that Asparagopsis will. [6][5][4]
Why it matters
Cattle release methane when they digest feed, and methane is a potent greenhouse gas. A feed additive that cut it without lowering weight gain or meat quality could reduce emissions from beef and dairy farms. A feed additive also reaches people through milk and meat, so its safety for animals and consumers has to be shown before it can be sold widely.
What stands in the way
- No approval for an Asparagopsis feed additive was found in the sources we could open for the EU, the US, Australia or New Zealand.
- Bromoform residues in milk are not settled. A Dutch advisory body (BuRO) says no safe maximum bromoform level in feed can currently be set, and it found no legal limit for bromoform in feed or animal products.
- Rumen effects are not settled. BuRO says exposure to bromoform from Asparagopsis in feed can affect the rumen mucosa within a few weeks in sheep and cattle.
- Dry matter intake fell 14% at the higher dose in the feedlot trial, which needs checking at larger scale.
- Supply is small. Publicly disclosed site capacities are in the tens to low hundreds of tonnes a year, and Australia publishes no consolidated national production figure.
- The trials are small. The feedlot trial analysed 20 steers, and its authors call for a larger feedlot trial.
Published forecasts
What others have predicted. These are their estimates, not ours.
| Who | Forecast | Timeframe | Made |
|---|---|---|---|
| Trevor Whittington, CEO of WA Farmers (opinion piece in Countryman) | Seaweed as a cattle feedstock will be at best no more than a niche market by 2030. The author calls this 'my guess' and cites no forecasting model for it. [9] | 2030 | 12 Jan 2022 |
| Fremantle Seaweed | First commercial sales of Asparagopsis feed, brought forward to 2027 with the acquisition of FutureFeed nursery and production assets. This is a company target, not an independent forecast. [8] | 2027 | 19 Oct 2026 |
Signals to watch
- A regulator in the EU, the US, Australia or New Zealand approving an Asparagopsis feed additive for cattle.
- A regulator setting a legal limit or safe maximum for bromoform in feed or animal products.
- Replicated trials across a full production cycle, in beef and dairy, that report methane and bromoform residues together.
- Fremantle Seaweed or another licensee reporting commercial sales volumes against the 2027 first-sales target.
- Dairy herd methane reductions at recommended doses holding up over a full lactation.
Sources
- peer reviewed paper
Red seaweed (Asparagopsis taxiformis) supplementation reduces enteric methane by over 80 percent in beef steers
Breanna M. Roque, Marielena Venegas, Robert D. Kinley et al.. PLOS ONE, Mar 2021. - government report
BuRO opinion on risks of bromoform by adding seaweed of the genus Asparagopsis to feed for ruminants
BuRO, Dutch National Forum Animal Welfare and Food Safety advisory body (via NVWA), Oct 2025. - review article
Methane reduction, health and regulatory considerations regarding Asparagopsis and bromoform for ruminants
CT Eason, PF Fennessy. New Zealand Journal of Agricultural Research, 2023. - government report
3-nitrooxypropanol - 4c1 (FAD-2019-0057)
European Commission Joint Research Centre, 15 Feb 2020. - government report
Safety and efficacy of a feed additive consisting of 3-nitrooxypropanol (Bovaer® 10) for ruminants for milk production and reproduction (DSM Nutritional Products Ltd)
EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP). EFSA Journal, 19 Nov 2021. - company announcement
Elanco Announces FDA Has Completed Review of Bovaer, First-in-Class Methane-Reducing Feed Ingredient, for U.S. Dairy Industry
Elanco Animal Health (company press release), 28 May 2024. - news
Fremantle Seaweed scales ocean farming to slash cattle methane
The Rural (third-party content in partnership with Fremantle Seaweed), 14 Oct 2026. - news
Fremantle Seaweed buys FutureFeed assets to lift supply
IT Brief Australia (news), 19 Oct 2026. - news
Reality check: seaweed as a feedstock for cattle likely to be nothing more than a 'niche market' by 2030
Trevor Whittington. Countryman (thewest.com.au), 12 Jan 2022.
Last reviewed 21 Oct 2026.