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 are: 

       i.          Synthetic chemicals i.e., Bovaer, Nitrate and halides

      ii.          Natural supplements and compounds i.e., Asparagopsis and tannins

     iii.          Oils and lipids i.e., Agolin 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 50 euros/cow/year. Using an example of 84 cow herd, the extra cost and reduction in carbon footprint two Scenarios are presented. 

Scenario 1: Cows are only fed the additives during the housing period.

Scenario 2: Cows are fed with additives throughout the year.

Table 9 Costs and emission reductions from anti-methane additives

Scenario 1Scenario 2
% of additive per yearDuring housing onlyHousing and grazing
Cost of additive(€)-1050-4200
Environmental impact
Total Emissions0.8240.809
Reduction in emissions (%)2.183.83
*kgCO2-eq /kg FPCM is the carbon footprint per kilogram of Fat and Protein Corrected milk
Herd size of 84 cows
Net savings/ cost are the savings or cost per year for the farm


The Farm Zero C project is leading dairy research trials at Teagasc Moorepark to investigate the efficacy of different dietary supplements, for example, Bovaer (3NOP) and Asparagopsis, and to establish their practical application within the dairy sector. 

Bovaer (3NOP)

A 10-week study is currently underway to establish if Bovaer (3NOP) is effective at reducing methane in grazing dairy cows. Data are being collected from 52 lactating dairy cows, which will be rotationally grazed for the duration of the experiment. The cows are fed 6.8 grams of the additive mixed with 500 grams of a coarse ration manually on exit from the milking parlour after both morning and evening milking. The additive is only effective for 2.5 hours after feeding therefore it is imperative that the cows get back to the GreenFeed machines soon after feeding so that their methane emissions may be measured. Milk samples are taken four times each week to establish if there is an effect of the additive on milk production, and dry matter intake will be measured on one occasion to ensure that there is no effect of the additive on intake. 

Other research

In other research projects nationwide, Bovaer (3NOP), seaweeds, oils and halides are also being trialled to establish their efficacy in sheep and beef animals. Research is also being undertaken to determine daily methane production in dairy, beef and sheep animals, 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.”


Anti-methanogenic additives are a novel technology and they are in the early stages of regularization and commercialisation.

3NOP is supplied by DSM: