Antimethanogenic Feed Additives

Antimethanogenic Additives

Over half of dairy emissions come from enteric methane.
Special feed additives suppress this gas, without affecting milk yield or animal health.

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The Climate Issue

Cows produce methane as part of their natural digestion. When they eat, microbes in the rumen break down fibrous feed. One of the by-products is methane, expelled mostly through burping.

On pasture-based farms, this enteric methane makes up over 55 % of total greenhouse gas emissions. It doesn’t hurt the cow, but it’s a major climate issue. Methane is 28 times more powerful than CO₂ and acts quickly in the atmosphere.

Unlike other sources, enteric methane is hard to capture or offset. Without action in the diet, these emissions remain high even on efficient farms.

The Solution: Feed Additives

Feed additives offer a new way to tackle enteric methane at source. These natural or synthetic compounds work inside the rumen, where they inhibit methanogenic microbes or alter fermentation.

Additives like 3-NOP (Bovaer®), algal-based products (Algolin®), or essential oil blends (SilvAir®) can cut methane by 20–40 % without affecting milk production. They allow cows to digest more efficiently, keeping energy for growth rather than waste gases.

Even at small doses, these additives have strong effects. Trials show methane drops immediately, with no negative impact on health or fertility.

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Key Benefits when using Feed Additives

Cut Emissions

Additives directly inhibit methane production in the cow’s rumen, reducing one of the hardest-to-abate farm emissions by up to 40 %.

Feed Efficiency

By shifting how cows digest fibre, some additives improve feed conversion – meaning more milk from the same feed or less feed for the same yield.

No Yield Loss

Properly tested additives do not reduce milk output or solids. They can be safely included in meal or TMR, even under high-performance systems.

Impact of using Feed Additives

Feed additives such as Bovaer® (3-NOP) are being tested in Irish dairy systems as a targeted way to reduce enteric methane. These compounds act in the rumen to inhibit methane-forming microbes without affecting milk yield or cow health.

Studies across EU pasture systems show that methane-reducing feed additives can:

Cut enteric methane by 20–30 %
Reduce total farm emissions by 4–7 %

Farm Zero C modelled two scenarios for a 93-cow herd at a cost of €75 per cow per year, showing clear emissions savings under both housing-only and year-round application.

Scenario	Methane Reduction	Net Cost/93 cows	GHG Emissions	% GHG Reduction
During the housing period	28%	€1744	0.924 kg CO₂-eq/kg milk	3.90%
During the housing + grazing period	28% (during housing) 10% (during grazing)	€6975	0.895 kg CO₂-eq/kg milk	6.77%

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Considerations

Additive Type & Supply

Additives like 3-NOP (Bovaer®), Algolin®, and SilvAir® are among the most trialled, but supply chains are still maturing. Cost, consistency, and ease of sourcing must be assessed before on-farm use.

Feeding System

Additives work best in Total Mixed Ration (TMR) or compound meal systems. In pasture-based systems, impact is lower due to variable intake, and daily feeding routines may need adjustment.

Regulations

Most additives require regulatory approval and declarations for traceability and carbon crediting. Always use certified products and keep records to meet EU or national compliance.

Implementation

Starting with methane-reducing feed additives is straightforward, but results depend on careful planning and follow-through. Below are key steps to help you introduce them effectively on the farm. These support both emission goals and herd performance.

1. Choose the right additive. Consult with your nutritionist or feed supplier to select a product proven for your herd and production system. Use one with verified methane reduction data.

2. Update the ration. Mix the additive into your existing meal or TMR. Ensure cows receive a consistent daily dose to achieve reliable methane reductions without disrupting intake.

3. Monitor performance. Track milk yield, solids, and cow health throughout the trial. Adjust dose or formulation based on outcomes and supplier guidance to optimise results.

Behind the Research

ODOS Tech was founded by Cian White and Alejandro Vergara, two sustainability specialists with deep expertise in agricultural climate action.

Alejandro (left), a PhD in environmental engineering from University College Dublin, helps farmers measure their carbon footprint and implement mitigation strategies to reduce their impact. Cian (right), a researcher at Trinity College Dublin with a PhD in ecology, works on restoring nature to increase biodiversity on farms using satellite imagery to monitor habitats.

Together, they helped lead the carbon and nature-based work for the Farm Zero C project at Shinagh Farm, one of Europe’s first net-zero dairy pilots. In 2020, they launched ODOS, a platform that built smart, science-based tools to help agri-food businesses protect the environment and restore nature.

Research

Teagasc Feed Trials

Irish and EU trials show that feed additives like 3-NOP can cut methane by 30 % or more, even in pasture-based diets. Milk yield remains stable, with minor feed efficiency gains in some herds.

Farm Zero C Pilot

At Shinagh Farm, trials with enteric inhibitors showed immediate methane reductions. The additives were well tolerated and caused no drop in production across the study period.

IPCC Recommendations

The IPCC lists enteric methane inhibitors as a key strategy for climate-smart livestock. While still emerging, these tools are likely to play a central role in future farm compliance and emissions planning.