The Science

A decade of world-class science

Asparagopsis seaweed, native to Australia, is the most efficient natural methane supplement available for livestock – capable of reducing methane emissions by more than 80 per cent in controlled conditions. Asparagopsis can be included in feed and supplements as a stabilised dried meal, or as an extract in edible oil. The research we have done so far included the supplement in:

  • feedlot and dairy total mixed rations; and

  • dairy cows supplemented twice daily at milking. What has the science proven?

Research has shown that Asparagopsis:

Is effective at reducing methane emissions by more than 80 percent in ruminant animals .

improves productivity and reduces feed and weight gain costs in commercial feedlot settings.

is safe for humans and ruminant animals, without effects on product quality or animal welfare.

Peer reviewed scientific papers

In vivo studies

Beef production:

Title: Productivity and methane emissions of commercial feedlot beef production significantly improved by dietary inclusion of Asparagopsis bioactives stabilized in canola oil
Reference: Kinley et al (2024) American Journal of Plant Sciences
Location: Australia 
Production System and Method: Beef feedlot - 81 day feeding period
300 Angus/Shorthorn-cross steers were fed a barley-based ration. 150 were supplementary fed Asparagopsis stabilised in canola oil (Asp-Oil) at a rate of 35mg bromoform (CHBr3) per kg of dry matter intake (DMI) in their finisher ration while the other 150 were fed straight canola oil in their total mixed ration.

Key findings  

  • Feed use efficiency significantly improved by 7.4% at full Asp-Oil inclusion
  • Asp-Oil significantly reduced methane emissions in a commercial feedlot setting
  • Carcass grading, meat eating quality and food safety were not affected by Asp-Oil
  • Asp-Oil had no negative impact on animal health and rumen wall

Title: Bioactive metabolites of Asparagopsis stabilized in canola oil completely suppresses methane emissions in beef cattle fed a feedlot diet 
Reference: Cowley et al (2024) Journal of Animal Science
Location: Australia 
Production System and Method: Beef feedlot – TMR; 81 day feeding period  
20 Angus heifers were fed one of four Asp-Oil treatment groups 0, 17, 34, and 51 mg bromoform/kg DMI in feedlot finisher diet with 21 d adaptation and 59 d experimental periods.  

Key findings  

  • CH4 yield reduced by 64%, 98% and 99%, respectively
  • Rumen temperature, pH, reduction potential, VFA and ammonia were unchanged
  • Rumen wall analysis was not different between groups, including Control
  • Average daily weight gain, FCE, and carcass characteristics were unchanged
  • Sensory evaluation improvements in 34 mg/kg DMI Asp-Oil group compared to control
  • No bromoform residue found in any sample [meat, fat, edible offal, faeces]
  • Iodide and bromide residues were maintained at levels safe for human consumption

This is an MLA Donor Company (MDC) project [P.PSH1351] and information is published on the MLA website. 

Title: Effect of SeaFeed, a canola oil infused with Asparagopsis armata, on methane emissions, animal health, performance, and carcass characteristics of Angus feedlot cattle
Reference: George et al (2024) Translational Animal Science
Location: Australia 
Production System and Method: Beef feedlot; 200 day feeding period
This 200-day study took place in a commercial feedlot, supplementing a steam-flaked wheat and barley diet with SeaFeed (25 mg bromoform/kg DMI).

Key findings  

  • Methane emissions were reduced by 51.7%
  • Performance improved, with 19.7 kg of additional live exit weight
  • The beef produced had similar eating quality to conventional beef.

Title: Red seaweed (Asparagopsis taxiformis) supplementation reduces enteric methane by over 80% in beef steers 
Reference: Roque et al (2021) PLOS ONE 
Location: United States 
Production System and Method: Beef feedlot – TMR, 147 day feeding period & 3 diets  
20 Angus-Hereford steers, 3 diets [high, mid, low forage] for 147 days fed one of three treatments; Control (no Asp-Meal), 0.25% OM Asp-Meal, or 0.50% OM Asp-Meal. 

Key findings  

  • CH4 yield reductions overall: 45 and 68%
    • High forage: 33% and 52%
    • Mid forage: 45% and 80%
    • Low forage: 70% and 80%, respectively.
  • H2 yield overall increased 336 and 590%, respectively
  • ADG, carcass quality, strip loin proximate analysis and shear force, or consumer taste preferences unchanged
  • DMI tended to decrease 8% and 14%
  • FCE tended to increase 7% at 0.25% and significantly increase 14% at 0.5% inclusion
  • Cost savings of $0.18 and $0.37 USD per kilogram of liveweight gain, respectively
  • No bromoform residue found in any sample [meat, edible offal]
  • Iodide in meat was elevated in Asp-Meal groups, however, was well within safe levels for human consumption limits
  • Bromide not tested

Title: Mitigating the carbon footprint and improving productivity of ruminant livestock agriculture using a red seaweed 
Reference: Kinley et al (2020) Journal of Cleaner Production 
Location: Australia 
Production System and Method: Beef feedlot – TMR; 90 day feeding period 
20 Brahman-Angus steers were assigned to one of four Asp-Meal treatments: 0.05%, 0.10%, and 0.20% of diet OM over a 90 day period.  

Key findings  

  • CH4 yield decreased by 9%, 38% and 98% and H2 yield increased by 0%, 380% and 1700%, respectively
  • No effect on DMI
  • Average daily weight gain improved for Asp-Meal treatment groups 0.10% and 0.20% by
    • 26% and 22% [full 90 days],
    • 53 and 42% [final 60 days], respectively.
  • VFA production
    • Total VFA was unchanged
    • Acetate decreased, propionate increased, and beneficially A:P decreased
  • No bromoform residue found in any sample [meat, fat, edible offal, faeces] for any treatment group
  • Iodide and bromide not tested

Dairy production:

Title: Effects of a range of effective inclusion levels of Asparagopsis armata steeped in oil on enteric methane emissions of dairy cows  
Reference: Alvarez-Hess et al (2024) Animal Feed Science and Technology
Location: Australia 
Production System and Method: Dairy - Pulse-fed; 41 day feeding period 
30 dairy cows were fed one of three treatment groups; Control (no Asp-Oil), ASP1 (132 mg CHBr3/day), ASP2 (267 mg CHBr3/day), ASP3 (409 mg CHBr3/day), and ASP4 (467 mg CHBr3/day)*.  

Key findings  

  • CH4 production decreased linearly
    • 6.5% (ASP1)
    • 7.8% (ASP2)
    • 24.4% (ASP3)
    • 38.3% (ASP4).
  • CH4 yield decreased linearly
    • 7.0% (ASP1)
    • 12.5% (ASP2)
    • 21.1% (ASP3)
    • 36.3% (ASP4).
  • Bromoform was detected in the milk & blood samples of ASP treatment groups**
  • No bromoform was detected in urine, feces, or breath of any treatment groups
  • Bromide was detected in the milk of all groups***
    • 2.9 mg/L for Control
    • 3.9 mg/L for ASP1
    • 4.9 mg/L for ASP2
    • 5.4 mg/L for ASP3
    • 6.8 mg/L for ASP4.
  • Iodide was detected in the milk of all groups***
    • 0.11 mg/L for Control
    • 0.16 mg/L for ASP1
    • 0.12 mg/L for ASP2
    • 0.20 mg/L for ASP3
    • 0.20 mg/L for ASP4.
*Consumption of Asp-Oil at an inclusion of 467 mg bromoform/day was determined by the dairy cows’ willingness to consume the grain-based supplement. This is likely due to the highly concentrated feeding of Asp-Oil to achieve the cow’s daily intake’s worth of Asp-Oil in two pulse feedings.
**The concentrations detected were demonstrated to be considerably lower than published safe concentrations in milk for human consumption (100 ug/L).
*** Both milk bromide and iodide contents of the all treatment groups are considered safe for human consumption.

Title: Effects on rumen microbiome and milk quality of dairy cows fed a grass silage-based  diet supplemented with the macroalga Asparagopsis taxiformis
Reference: Krizsan et al (2023) Frontiers in Animal Science  
Location: Sweden 
Production System and Method: Dairy – TMR 
The objective was to determine the effects on rumen microbiome and milk quality of  reducing the CH4 using Asp-Meal to the TMR diets of 6 Nordic Red dairy cows for 21 days. 

Key findings  

  • CH4 production decreased by 60%
  • CH4 yield decreased by 54%
  • CH4 intensity decreased by 58%
  • DMI was decreased and subsequently milk production and milk fat yield similarly decreased
  • FCE increased 9.8%
  • Bromoform content of the milk was found in both groups*
    • 4.09 µg/L for Control
    • 4.92 µg/L for Asp-Meal.
  • Bromide was detected in the milk of both groups**
    • 5.1 mg/L for Control
    • 43.2 mg/L for Asp-Meal.
  • Iodide was detected in the milk of all groups**
    • 139 ug/L for Control
    • 2105 ug/L for Asp-Meal.
  • Increased propionate, decreased acetate for the Asp-Meal group
  • Shift from Methanobrevibacter to Methanomethylophilaceae
  • Lower relative abundance of Prevotella bacteria
  • Changes in milk fat odd-numbered and branched chain fatty acids
*The concentrations detected were demonstrated to be considerably lower than published safe concentrations in milk for human consumption (100 ug/L).
**Both milk bromide and iodide contents of both treatment groups are considered safe for human consumption.

Title: Twice daily feeding canola oil steeped with Asparagopsis armata reduced methane emissions of lactating dairy cows with no effect on intake or milk yield
Reference: Alvarez-Hess et al (2023) Animal Feed Science and Technology
Location: Australia
Production System and Method: Dairy - Pulse-fed; 32 day feeding period
39 dairy cows were fed one of three treatment groups; Control (no Asp-Oil), ASP1 (Asp-Oil without seaweed biomass), and ASP2 (Asp-Oil with seaweed biomass) both fed at inclusion rates of 16.7 mg bromoform / kg DMI*

Key findings  

  • CH4 production decreased 44% and 39%
  • CH4 yield decreased 42% and 34%
  • CH4 intensity decreased 38% and 31%, respectively
  • Bromoform was detected in the milk of all groups**
    • 0.30 ug/L for Control
    • 2.13 ug/L for ASP 1 (without seaweed biomass)
    • 2.69 ug/L for ASP 2 (with seaweed biomass).
  • Bromide was detected in the milk of all groups***
    • 2.67 ug/L for Control
    • 4.76 ug/L for ASP 1 (without seaweed biomass)
    • 4.92 ug/L for ASP 2 (with seaweed biomass).
  • Iodide was detected in the milk of all groups***
    • 0.47 ug/L for Control
    • 0.51 ug/L for ASP 1 (without seaweed biomass)
    • 0.69 ug/L for ASP 2 (with seaweed biomass).
*Consumption of Asp-Oil at an inclusion of 16.7 mg bromoform/kg DMI was determined by the dairy cows’ willingness to consume the grain-based supplement. This is likely due to the highly concentrated feeding of Asp-Oil to achieve the cow’s daily intake’s worth of Asp-Oil in two pulse feedings.
**The concentrations detected were demonstrated to be considerably lower than published safe concentrations in milk for human consumption (100 ug/L).
*** Both milk bromide and iodide contents of the all treatment groups are considered safe for human consumption.

Title: Effects of the macroalga Asparagopsis taxiformis and oregano leaves on methane emission, rumen fermentation, and lactational performance of dairy cows 
Reference: Stefenoni et al (2021) Journal of Dairy Science 
Location: United States 
Production System and Method: Dairy – TMR; 4 studies conducted [two in vitro and two animal] 

Key findings  

  • Experiment 1: In vitro, 1% Asp-Meal DM inclusion rate and resulted in 98% CH4 reductions.
  • Experiment 2: 6 dairy cows fed 3 Asp-Meal inclusion rates [0.25, 0.50, and 0.75% DM inclusion]
    • 0.50 and 0.75% Asp-Meal levels resulted in CH4 yield reductions of 80%.
  • Experiment 3: 20 dairy cows were fed one of four treatments; Control, 0.25% Asp-Meal DM, 0.5% Asp-Meal for 28 days.
    • CH4 yield unchanged for 0.25%, but decreased by up to 65% for 0.50%
    • H2 yield increased by 134% and 527%, respectively
    • DMI & Milk yield was unchanged in 0.25% DM group, however DMI decreased in the 0.50% Asp-Meal group and subsequent changes in milk yield & lactose were observed
    • No changes in sensory characteristics of milk
    • Bromoform content of the milk was found in both groups*
      • 16.5 µg/L for Control
      • 28.9 µg/L for 0.5% and 0.5% DM Asp-Meal.
    • Milk iodide [2.96 ug/mL] and bromide [40.4 ug/mL] were observed for the 0.50% Asp-Meal DM group**.
  • Experiment 4: Asp-Meal was stored in different conditions [light vs dark & over time] for 120 days and bromoform degraded linearly over time which explains why CH4 was not reduced similarly between experiment 2 and 3 and within the last two 28 d periods of experiment 3.
*The concentrations detected were demonstrated to be considerably lower than published safe concentrations in milk for human consumption (100 ug/L).
**Iodine and bromine in the Asp-Meal were not reported, however this was a wild-harvested product thus was likely to be higher than global cultivated Asp-Meal standards. The Asp-Meal used in this study would not deliver expected quality standards.

Title: Inclusion of Asparagopsis armata in lactating dairy cows’ diet reduces enteric methane emission by over 50 percent 
Reference: Roque et al (2019) Journal of Cleaner Production 
Location: United States 
Production System and Method: Dairy – TMR  
Twelve lactating cows were randomly assigned to each of the three treatment groups [Control, 0.5% OM Asp-Meal, and 1.0% OM Asp-Meal for 3- 14 days periods (latin-square design).  

Key findings  

  • CH4 production decreased by 26.4% and 67.2%
  • CH4 yield decreased by 20.3% and 42.7%
  • CH4 intensity decreased by 26.8% and 60%, for 0.5% and 1.0% OM Asp-Meal, respectively
  • DMI was decreased and subsequently milk production and milk protein similarly decreased
  • FCE increased 20% and 75%, respectively
  • Bromoform content of the milk was found in all groups*
    • 0.11 µg/L for Control,
    • 0.15 µg/L for 0.5% and 1.0% OM Asp-Meal.
  • Bromide and iodide not tested in this study
*The concentrations detected were demonstrated to be considerably lower than published safe concentrations in milk for human consumption (100 ug/L).

In vitro studies

Title: Effects of a range of effective inclusion levels of Asparagopsis armata steeped in oil on enteric methane emissions of dairy cows
Reference: Alvarez-Hess et al (2024) Animal Feed Science and Technology
Location: Australia
Production System and Method: Dairy – Cow’s Milk & Milk Processing
Milk collected from “Twice daily feeding canola oil steeped with Asparagopsis armata reduced methane emissions of lactating dairy cows with no effect on intake or milk yield”. During the measurement period, all the raw milk produced by the experimental cows on the afternoon of d 31 and the morning of d 32 was collected into buckets for each cow and subsampled to create different samples for analysis of (i) FAME and (ii) acid- and rennet-induced gelation properties.

Key findings  

  • FAME (milk Fatty Acid Methyl Ester analysis)
    • Small differences in milk fatty acid profile were noted between the treatment and control groups but the practical significance of these differences was minimal and would be outweighed by flux observed within seasons, geographies and environments.
  • Headspace volatiles
    • Few volatiles were detected at trace levels in the headspace of the milk samples, dominated mostly by the short chain fatty acids and with no overall differences measured between the CON and ASP treatment groups indicating that Asp-Oil supplementation would not lead to a detectable difference in product flavour and smell.
  • Acid- and rennet- induced gelation properties
    • Feeding Asp-Oil to dairy cows showed no effect on rennet-induced or acid-induced gelation characteristics suggesting that the inclusion of ASP-Oil in dairy diets would not hinder the processing of raw milk into cheese and yoghurt, respectively.

Title: The anti-methanogenic efficacy of Asparagopsis taxiformis.
Reference: Ahmed et al (2024) Animal Feed Science and Technology
Location: Australia
Production System and Method: in vitro study
This study evaluated the differences in the anti-methanogenic potential of Asparagopsis taxiformis biomass versus bromoform.

Key findings  

  • The anti-methanogenic potential of Asparagopsis taxiformis biomass is significantly higher than that of bromoform alone
  • Bromoform was the strongest anti-methanogenic compound in the seaweed. However, the biomass was 36-40% more powerful than bromoform alone
  • The biomass and bromoform had no negative impacts on in vitro rumen fermentation
  • The role of bioactive compounds other than bromoform in Asparagopsis biomass is significant.

Title: Reducing methane production from stored feces of dairy cows by Asparagopsis taxiformis 
Reference: Ramin et al (2023) Frontiers in Sustainable Food Systems 
Location: Sweden 
Production System and Method: 
Faeces of cows from Kriszan et al 2023 was used in an in vitro study that evaluated faecal CH4 production with and without Asp-Meal [0.5% OM] application. Faecal samples from the two groups were divided into two subsamples [4 treatment groups total].  

Key findings  

  • Dietary Asp-Meal effects on manure CH4 production
    • Control 1 (no dietary or faecal Asp-Meal) vs Control 2 (dietary Asp-Meal, no faecal Asp-Meal)
      • CH4 production, bacterial & methanogen populations unchanged*.
  • Faecal Asp-Meal application on manure CH4 production
    • Control (no Asp-Meal) vs Faecal Asp-Meal application
      • 44% reduction in CH4 production**.
*This indicates that the CH4 reduction capability of Asp-Meal fed to cattle does not persist in the gastrointestinal tract of the animal through to faecal processing. This may be beneficial to producers who have invested in anaerobic digesters where the production and capture of CH4 is important.
**This may be a beneficial strategy to producers who want to decrease overall farm emissions and don’t have capabilities to build anaerobic digester infrastructure.

Title: Evaluating the effect of phenolic compounds as hydrogen acceptors when ruminal methanogenesis is inhibited in vitro – Part 2. Dairy goats 
Reference: Romero et al (2023) Animal 
Location: Spain 
Production System and Method: in vitro study 
Performed four in vitro incubation experiments to evaluate H2 acceptors during CH4 inhibition using rumen inoculum from Murciano-Granadina adult goats. 

Key findings  

Experiment 1: Asp-Meal was added to in vitro batch fermentation vessels at different concentrations (0, 1, 2, 3, 4 and 5% DM basis) in 24 h incubations for the purpose of CH4 mitigation.

  • CH4 production decreased by up to 99%, 2% DM Asp-Meal plateau
  • increase in rumen H2 accumulation
  • VFA profile changed by the inclusion of Asp-Meal
    • Decreased acetate
    • Increased propionate
    • Decreased acetate:propionate
    • Total gas production, pH, lactate, and ammonia concentration unchanged.
Experiment 2: Phenolic compounds [phenol, catechol, resorcinol, hydroquinone, pyrogallol, phloroglucinol, gallic acid and formic acid] at 6 mM with Asp-Meal at 2% DM in sequential batch cultures for 5 days.
  • Phloroglucinol
    • decreased H2 accumulation
    • o increased total gas production, VFA production and the acetate:propionate ratio.
Experiment 3: Phloroglucinol at different concentrations (0, 6, 16, 26 and 36 mM) combined with Asp-Meal in sequential batch cultures for 5 days
  • decreased H2 accumulation
  • decreased abundances of archaea, protozoa and fungi abundances
  • increased total gas production, total VFA production and the acetate:propionate ratio

Title: Exploration of methane mitigation efficacy using Asparagopsis-derived bioactives stabilized in edible oil compared to freeze-dried Asparagopsis in vitro 
Reference: Kinley et al (2022) American Journal of Plant Sciences  
Location: Australia 
Production System and Method: in vitro – Asp-Meal versus Asp-Oil  
Asp-Meal and Asp-Oil were tested at similar inclusion rates in vivo for 24, 48, and 72 hours. 

Key findings  

  • CH4 yield reductions similar between Asp-Meal and Asp-Oil
  • Total gas production, dry matter digestibility, or VFA were not different between Asp-Meal, Asp-Oil, and Control groups.
View study

Title: Changing the proportions of grass and grain in feed substrate impacts the efficacy of Asparagopsis taxiformis to inhibit methane production in vitro 
Reference: Kinley et al (2021) American Journal of Plant Sciences 
Location: Australia 
Production System and Method: in vitro – grass versus grain diets 
5 diet gradients between 100% Rhodes grass (RG) to 100% barley grain (BG) and Asp-Meal inclusion rates were applied [0, 0.05, 0.08, 0.11, 0.14, 0.16 mg bromoform / kg OM] were tested for 24, 48, and 72 hours of fermentation. 

Key findings  

  • CH4 yield
    • decreased with higher Asp-Meal
    • decreased with higher BG
    • efficacy of Asp-Meal was enhanced with higher BG.
  • Digestibility
    • increased with fermentation duration
    • increased with higher BG
    • no change from Asp-Meal.
  • Total VFA
    • increased with fermentation duration
    • increased with higher BG
    • no change induced by Asp-Meal.
  • Acetic and propionic acid ratio (AA:PA)
    • decreased with higher BG
    • decreased with higher Asp-Meal.

View study

Other studies

Title: Rumen microbial degradation of bromoform from red seaweed (Asparagopsis taxiformis) and the impact on rumen fermentation and methanogenic archaea
Reference: Romero et al (2023) Journal of Animal Science and Biotechnology
Location: Spain
Production System and Method: in vitro study
In vitro study that evaluated the degradation process of bromoform from Asp-Meal (2% DM inclusion) in the rumen and whether this process is diet-dependent.

Key findings  

  • CH4 production decreased by 98% over 72 hours
  • Acetate:propionate decreased significantly
  • Bromoform 90% degraded within the first 3 h of incubation.*
  • di-bromomethane increased first 6 h then decreased towards the end of the incubation.
    • Both bromoform and di-bromomethane were affected by the type of diet
    • Fermentation rate is not a driving factor involved in bromoform degradation.
  • Methanogen growth inhibited by bromoform inclusion
*The study demonstrated that bromoform from Asp-Meal is quickly degraded to di-bromomethane in the rumen which is also degraded over time. These results provide an explanation as to why bromoform residues are not found in Asp-Meal animal studies.

Title: Potential environmental impact of bromoform from Asparagopsis farming in Australia
Reference: Jia et al (2022) Atmospheric Chemistry and Physics
Location: Global
Production System and Method: Asparagopsis farming and respective bromoform production

Key findings  

Australian Scenario: includes supply 50% of beef feedlots & dairies with Asparagopsis at 0.4% DM Asp-Meal daily. 35 tonnes of Asp-Meal/year.

  • Under normal growing conditions, bromoform release would be
    • less than 0.9% of Total Australian bromoform emissions
    • less than 0.01% of Total Global bromoform emissions (from both natural & anthropogenic sources).
Global Scenario: includes assuming a 30x scalability of Australian scenarios for global Asparagopsis supply sourced from Australia. 1,000,000 tonnes of Asp-Meal/year.
  • Under normal growing conditions, bromoform release would be
    • less than 0.5% of Total Global bromoform emissions (from both natural & anthropogenic sources).
*Important to note that these estimates come from assumptions made on 1.) average growth rate and bromoform synthesis of Asparagopsis and 2.) open ocean and a subset of terrestrial confinement systems, all of which have and will continue to improve over time.

Title: Shelf‑life stability of Asparagopsis bromoform in oil and freeze‑dried powder
Reference: Tan et al (2022) Journal of Applied Phycology
Location: Australia
Production System and Method: in vitro – bromoform stability in Asp-Meal and Asp-Oil
Asp-Meal and Asp-Oil were tested under different circumstances to determine bromoform stability within each Asparagopsis product.

Key findings  

  • Asp-Meal
    • Not affected by fluorescent light
    • Sensitive to temperatures above 4°C for periods longer than 4 weeks.
  • Asp-Oil
    • Negatively affected by fluorescent lighting at temperatures above 25°C
    • Negatively affected by exposure to open-air
    • Not affected by temperatures ranging from -20°C to 40°C in airtight containers & absent of fluorescent light for at least 24-weeks.