The introduction of anti-methanogenic in the diets of animals is an innovative technology aimed at reducing biogenic methane in order to abate overall agricultural emissions.


Methane is a greenhouse gas released by ruminants during enteric fermentation or manure storage. Methane associated with ruminant livestock production accounts for two-thirds (68%) of Irish agricultural GHG emissions (Environmental Protection Agency (EPA), 2021). 

Why should I consider anti-methanogenic additives to reduce methane?

Reducing methane emissions will have a big role to play in achieving overall agricultural emissions reduction targets of between 22 and 30% by the year 2030 as set out by the Irish government (Government of Ireland, 2021). The use of anti-methanogenic feed additives will help Irish farmers to achieve these targets in a timely fashion.   

How do anti-methanogenic additives work?

The video below from Teagasc shows how anti-methane additives work in beef cattle.

Feed additives work by either inhibiting the microorganisms that produce methane in the rumen or by changing the volatile fatty acid profile in the rumen, subsequently reducing methane emissions without reducing animal performance.

Common anti-methanogenic feed additives include Bovaer (3NOP), halides, Seaweed, and Rapeseed oil.


Economic and Environmental Benefits

Research is still underway to measure the cost-effectiveness of different additives. 

On average the feed additives cost about €75/cow/year. Using an example of 93 cow herd, the extra cost and reduction in carbon footprint two Scenarios are presented. 

Costs and emission reductions from anti-methane additives

Scenario 1
Additives during the housing period only
Scenario 2
Additives throughout the year
Effectiveness of additive(methane reduction)28% reduction28% reduction during housing and 10% when grazing
*Cost of additive (€)-1744-6975
Environmental impact
Total Emissions (kgCO2-eq /kg FPCM)0.9240.895
Reduction in emissions (%)3.906.77
kgCO2-eq /kg FPCM is the carbon footprint per kilogram of Fat and Protein Corrected milk
*Estimated additive cost of €75/cow per year, a total of 93 cows
Net savings/ cost are the savings or cost per year for the farm


Current research being undertaken as part of the FZC project aims to trial different dietary additives to establish their efficacy and practical application within the Irish dairy sector. These will focus on press cake, Bovaer (3NOP), a halide, and Asparagopsis. This research is being carried out by Teagasc Moorepark using greenfeed machines. Findings from Bovaer studies showed that feed additives are effective at reducing methane, however, their efficacy in grass-based dairy cows may be enhanced by slow-release technology.

Other research

In other research projects nationwide, Bovaer (3NOP), seaweeds, oils, and halides are also being trialed to establish their efficacy in sheep and beef animals. Research is also being undertaken to determine daily methane production in dairy, beef, and sheep, in addition to the revision of methane emission factors through projects like Rumen Predict,  MASTER, and METH-ABATE.

Key findings from previous research in TMR-based dairy systems include:

  • The additive Bovaer (3NOP) has shown consistency in methane reduction with an average of 30% reduction when administered in feed for dairy cows (Melgar et al., 2021; van Wesemael et al., 2019; Yu et al., 2021).
  • Nitrates can be effective in methane abatement, however, there is the risk of toxicity leading to ill health or death of livestock if the inclusion rate is too high or there is no gradual adaptation (Rooke et al., 2019)
  • Rapeseed oil may significantly reduce methane emissions however some research has demonstrated reductions in body weight where rapeseed oil has been used (Chagas et al., 2021; Ramin et al., 2021).
  • Asparagopsis may reduce methane production by approximately 40%, however, gradual adaptation is necessary (Duarte et al., 2017; Kinley et al., 2016; Roque et al., 2019).

Links to more research

GHG Emissions and methane abatement

Seaweed and Seaweed Bio-actives for Mitigation of Enteric Methane: Challenges and Opportunities 

Strategies to reduce enteric methane emissions from agriculture

Summary of scientific research on how 3-NOP effectively reduces enteric methane emissions from cows


The following regulations and actions apply to the use of anti-methanogenic dietary additives.

EU 2030

National Climate Action Plan

AgClimatise roadmap – To reach net zero emissions in agriculture by 2050, the use of anti-methanogenic additives is outlined in Action 7 in the AgClimatise roadmap. 

Action 7: Continue to invest in novel feed additives to reduce biogenic methane.”


3NOP (Bovaer) is supplied by DSM: