How feeding methane inhibitors can help cut emissions

Methane inhibitors supplied in feed rations could play a significant role in reducing greenhouse gas emissions in ruminants.

However, no one size fits all, advises Annie Williams, ruminant nutritionist and business development manager at the UK AgriTech Centre.

“We need to think of them as a tool in the toolbox to reduce methane emissions in ruminants, among a whole host of other things,” she said. 

See also: Methane-suppressing feed additive approved for use in UK

“Each farm will be different, but when we look at UK averages, we see that about 45% are coming from enteric fermentation – and this is where we might really be able to make a difference with methane inhibitors.”

Annie stressed that progress is being made in reducing greenhouse gas emissions.

While dairy contributes about 3.4% of emissions worldwide, the UK is recognised as a global leader with a carbon footprint for milk at about 43% of the global average, she said.

Milk and beef processors as well as retailers were looking at how to reduce their Scope-3 emissions, she said, adding:

“Clearly, methane is a major part of that.

“There’s a difference between methane inhibitors that have no other benefit see, and additives that inhibit and potentially have additional performance benefits, for example.

“We’re looking at all different ways of [reducing emissions], and that might include incentivisation for using different methods of inhibiting – that’s definitely an area Defra is looking at as well.”

Methane reduction

Rumen microbes produce a lot of hydrogen, which must be removed for rumen function to continue.

Normally, the hydrogen combines with carbon dioxide to form methane, which the cow belches out.

Direct methane mitigation can be achieved in three ways, according to Cargill Animal Nutrition’s technology application specialist, Dr Phil Ingram:

• Changing the microbes in the rumen that emit methane
• Inhibiting the production of methane
• Redirecting the hydrogen that goes into methane production and putting it to another use.

Below is an introduction to Cargill’s methane inhibitor SilvAir, and two further products licensed for use in the UK. Each is accounted for in one or more carbon footprinting tools.

SilvAir

Cargill has traditionally focused on trying to improve productivity for every unit of feed intake – which is closely related to methane output, said Phil.

SilvAir, however, employs a direct approach (see “Direct methane mitigation”), reducing methane production by about 10% with no change to milk production.

How it works

The product contains nitrate, which preferentially combines with the hydrogen to produce ammonia.

The rumen microbes convert this into microbial protein, which the cow can use and which is also a more energy-efficient route for hydrogen removal.

“That’s one of the reasons the effect is very consistent across diets and [ruminant] types,” said Phil.

Bovaer

Adrian Packington is a ruminant nutrition consultant for the Swiss life sciences company DSM Firmenich.

He said that research indicates that when the methane inhibitor Bovaer is fed at the correct dose in a total mixed ration, it “reliably and consistently reduces methane without exception”. 

Bovaer can reduce methane output by up to 33%.

Adrian stresses this reduction is an absolute measure of methane produced a cow a day, and does not refer to methane intensity.

This is measured in grams of methane for each kilogram of fat- and protein-corrected milk (FPCM).

“It is the only product specifically approved for methane reduction,” he said, adding that inclusion in the diet results in no significant change in milk production, milk composition or quality, feed intake, fertility or herd health.

How it works

“It blocks a specific enzyme in the archaea [rumen micro-organisms that produce methane] and disrupts methane synthesis,” he explained.

“It does not kill the archaea and has no impact on other rumen microbes.

“It’s broken down in the rumen with no residues in meat or milk, and there’s no evidence of reduced efficacy in studies lasting more than one year.”

RumiTech

While formal claims cannot yet be made about RumiTech’s methane mitigating properties, published research is in the public domain.

This is according to Stephen Kenyon, commercial director of feed and nutrition company Harbro.

Data suggest the natural flavouring compound reduces methane, as well as delivering production improvements, he said.

A meta-analysis of 23 in vivo studies (published in Animals, 2020) of RumiTech’s effect on productivity in dairy cows showed an average yield improvement in FCPM of 3.7%.

Feed efficiency was up 4.5% and a there was a methane reduction of 12.9% ( if measured as g/kg FPCM) or 9.9% (as g/kg dry matter intake), he added.

The active ingredient, developed for its performance benefits, is supplied by Agolin.

How it works

RumiTech is a blend of botanical extracts and essential oils that modulates and affects the rumen microbial populations, Stephen explained.

Annie Williams was speaking at a recent webinar run by the Royal Agricultural Society of England.