Methane reducing feed additives – the story so far

07 September 2022


Methane reducing feed additives have been cited as an innovative way for ruminant livestock farmers to help reduce methane emissions from their livestock. NFU livestock advisor Harriet Henrick looks at the story so far. 

Currently most additives are either incorporated into a total mixed ration, for example seaweed or biochar or top dressed onto feed.

The majority of the compounds work to limit the cycle in the rumen that creates methane, therefore different diets (forage vs concentrate) can have a large impact on emissions reductions.

For the additive to be effective it also needs to be consumed at the same time as the normal diet. For this reason, the options for grazing ruminant livestock are limited until options such as a slow-release bolus or mineral block have been further considered.

Risk assessment needed

The FSA is responsible for licensing all feed products for livestock and would have to carry out a robust risk assessment considering the impacts of each additive on animal health and welfare, food safety risks, risk to workers, wider environmental risks and the efficacy of an additive before licensing for use in feed to reduce methane.

Currently there are no additives licensed and available for use in the UK, however applications have been submitted and there are trial farms in the UK.

Below is a table of some additives currently known to reduce methane in ruminant livestock and any associated information we have alongside them.

Most products impact on methane reduction is significantly affected by the animals diet at the time, with the biggest effect seen on those animals consuming a diet high in cereals compared to forage based systems.

Additive table


Synthetic or natural

GHG % reduction claim

Impacts on health or productivity

Food safety impacts & approval

Essential Oils such as garlic or citrus



Limited evidence of higher productivity & reduced fly burden anecdotally.

None known, but can leave residual taste in the milk.





Damage to rumen wall has been seen.  Improved feed efficiency. Algae based feeds can increase fat content of diets and reduce somatic cell counts in milk.  

Bromide and iodine residues in animal products.




Can improve quality of manure.

None Know




Milk solids and proteins increased.

Approved in Brazil, Chile and recently Europe.




Risk of toxin poisoning due to accumulation of nitrite (NO2).  Little reason to expect improved productivity in nitrogen adequate diets, but it may provide an alternative to urea.

Nitrite can also pass into the milk and urine which gives a bitter taste.  Commercial feed-grade product SilvAir already available and in demos in Brazil and EU.




Already used in dairy to increase yields and good evidence of increased productivity in beef but results can vary depending on other factors.

Widely used in North America.

Propionate Precursors (e.g., fumaric Acid, malate, aspartate)



Some studies show a very small increase in digestibility of food.

CH4 reductions are linked to the amount fed in most circumstances but feeding substantial quantities has impacts.

Antimicrobials or Ionophores.(Monensin illegal in UK)



Methane reductions are only short term as the microbial population adapt to the changes. Increased feed efficiency

Product a natural antibiotic and currently illegal for use in livestock production in the UK.

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