By Melissa Smith and Rob Verkerk PhD

UK dairy giant Arla sparked controversy recently by announcing the trial of Bovaer®, a feed additive designed to reduce methane emissions by gut microbes in cattle that are estimated to be responsible for 6% of greenhouse gas emissions. This initiative prompted heated discussions on social media, with critics decrying further interference in food production systems and questioning the safety of such interventions. Some consumers ceremoniously threw away their milk and even threatened to boycott supermarkets, questioning the safety and ethics of such interventions.

Bovaer manufacturer DSM Firmenich has hit back, insisting the additive is safe, citing regulatory approvals and over two years of global commercial use.

Yet, conversely the controversy has provided a platform for many smaller farmers and producers to promote regenerative farming methods as they reassure their existing (and potential) customers that their cows are and will remain, additive free.

Why Focus on Methane?

As the focus on CO₂ moves stage left, methane is taking centre stage, with emissions from agriculture and in particular grazing animals, coming into sharp focus.

Methane is a potent greenhouse gas, produced by both the natural environment and human activities. It’s significantly more effective at trapping heat than carbon dioxide. While livestock is cited to be a major methane contributor, its exact impact on global greenhouse gas emissions remains hotly debated. Critics rightly highlight flaws in the arguments for methane reduction in cattle, noting that ecosystems will still produce methane even without livestock.

Figure 1. Methane emissions by sector showing the total emissions assigned to agriculture. Source: Our World in Data

Reducing methane has become a priority among those controlling climate change mitigation because it dissipates quickly—within a decade—making it an attractive target for accelerating decarbonisation. This urgency has led to initiatives such as the Global Methane Pledge, signed by 150 countries in September 2024, and policies such as Denmark's methane tax on livestock (the first such tax to be implemented) and the Reducing Methane from Organic Waste Declaration, which was made at COP29, designed to target methane from organic waste. There’s even a Global Methane Budget.

What Is Bovaer?

The main active in Bovaer is 3-nitrooxypropanol, or 3-NOP, a synthetic organic compound that is closely related to other nitrate esters that are widely used as explosives or propellants. The formulation also includes propylene glycol and silicon dioxide.

Bovaer works by blocking the activity of an enzyme, coenzyme M reductase (MCR), which is crucial for methanogenesis, the process by which ruminant animals like cows and sheep produce methane in their rumen, the first and largest of their 4 specialised stomach compartments. Methane, that emanates largely from cows belching (not, as legend has it, farting), might be seen as problematic for humans concerned about climate change, but it plays a crucial role in maintaining a healthy rumen environment.

By inhibiting MCR, Bovaer prevents the final step where hydrogen (H₂) and carbon dioxide (CO₂) are converted into methane (CH₄). Methane is the primary component of natural gas, produced naturally deep underground or in the ocean floor, and is exploited by humans for heating, cooking and electricity generation. But don’t blame methane on cows and sheep! It is also well known to seep naturally from reservoirs beneath the seafloor, through volcanoes, faults, fractures and permeable rock layers, and after earthquakes and landslides that disturb underground reservoirs.  

Two big concerns we have about interfering with ruminants’ methane production are:

1. Microbiome imbalance. When these animals ferment tough plant material that humans can’t digest in the oxygen-free (anaerobic) environment of the rumen, they produce volatile fatty acids as their primary energy source. Hydrogen is the byproduct of this fermentation (along with carbon dioxide) and, critically, a group of gut microbes known as methanogens, thrive on this hydrogen and are essential in breaking down pasture from which energy for the ruminants is then derived.  If the levels of hydrogen build up too much, the fermentation process in the rumen is inhibited, reducing the ability of the animals getting energy from their food.
2. pH imbalance. The second thing that methane does in the rumen is stabilise the pH (acid/alkaline balance) and this balance is crucial for the microbes responsible for digestion.

These are issues that are under-researched and, consequently, widely ignored.

Bovaer’s History

Work to find ways to reduce methane emissions from livestock started in earnest well over a decade ago. The key ingredient in Bovaer, 3-NOP, was discovered in 2010, with the first trials in cattle taking place in 2011. The first market authorisation requests were filed in 2019, with approvals following in 2021.

The claims for its efficacy are supported by over 70 peer-reviewed studies that claim it can cut methane emissions by 30% in dairy cows and 45% in beef cattle. However, concerns remain. In its assessment of Bovaer, the UK’s Food Standards Agency (FSA) notes a range of concerning adverse effects, including:

• Reduced feed and water intake, smaller ovaries, and lower heart weight in cows
• Rat studies have raised red flags about fertility, carcinogenicity and genotoxicity at doses higher than the recommended level for general use
• Handling the additive could also pose risks to farmers including skin irritation, serious eye damage and possible fertility issues
• In one study a metabolite of Bovaer was detected in the milk of 3 out of 4, although it was dismissed due to its limited sample size.

That's before we take into account the fact that grass-fed cattle present a completely different picture of the carbon cycle, compared with feedlot, grain-fed cattle. This can only be assessed using comprehensive life cycle analysis (LCA), and recent studies (here and here) have shown that well-managed grasslands and pastures have the capacity to absorb so much more carbon than feedlot systems, both in the pasture and in the soil, so offsetting methane production. You also have to factor in that most of the grain feed (e.g. maize, wheat) in feedlot systems is imported great distances, further increasing the carbon footprint.     

Should we be surprised that Bovaer is being pushed as hard as it is? Just when humans are trying to find out ways of improving their health by manipulating our own gut microbiomes, one agrochemical company, supported by regulatory authorities around the world, see fit to destroy the microbiome of animal species that have been central to our recent post-agricultural success. 

Despite these concerns, many regulatory bodies, including the EU, UK, and US, have approved Bovaer, and it’s now authorised and available for use in over 65 countries.

In the UK, there are calls to mandate its use in livestock farming. However, long-term studies on its environmental and biological impacts both on animals, milk and meat products and safety for human consumption are lacking, despite short-term study of changes to the cows’ microbiomes showing a reduction in methane producing microbes.

The Bigger Picture: Destroying Real Agriculture

Reducing methane emissions comes alongside broader efforts to curb meat consumption, which have been linked, often tenuously, to chronic health issues and, more latterly, climate change. Questions arise around the focus on methane-reducing additives, linking to a powerful corporate-driven agenda that undermines traditional regenerative farming in favour of industrial-scale solutions.

Image source: Beef Cattle Research Council

Pressure from multiple, but often nebulous quarters is increasing on farmers to turn their backs on traditional regenerative farming methods, which work with natural carbon cycles. All the while, large swathes of agricultural land are bought up in ongoing land grabs. In turn, financial rewards are being offered to farmers to adopt methane-reduction technologies, in order to reduce their carbon footprints through the generation of carbon credits, which can then be sold via the carbon markets. The US Department of Agriculture has also made substantial funding available to support farmers using methane reduction methods such as Bovaer, making it very hard for smaller farmers to refuse to use such technologies in the long run.

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Many schemes are being implemented to reduce meat consumption including the C4 Cities Good Food Cities Accelerator scheme aims to get cities to reduce their climate impact by aligning with the EAT Lancet Planetary Diet. This in turn pushes significant reductions in the consumption of animal products and thus methane.

But there are still a few influential mainstream research institutes that believe in agriculture. The Potsdam Institute for Climate Impact (Röckstrom), for example, has just published a report discussing unsustainable land use, caused mainly by industrial agriculture, and proposes to tackle it using regenerative agricultural practices. The release of the report coincides with the start of COP16 – ‘Convention to Combat Desertification’, the main purpose of which is to “Accelerate restoration of degraded land by 2030 and beyond”, giving hope that we can retreat from the brink of the environmental degradation wrought by humans, currently mis-categorised under the heading of ‘climate change’.

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The Alternative: Work With, Not Against, Nature

At the end of the day, reducing methane isn’t just about what goes into and comes out of a cow. It’s also about what’s happening in the environment around them. Using regenerative farming techniques promotes improved soil health, natural carbon capture and increased biodiversity. Whereas highly industrialised feedlot production of livestock creates multiple environmental impacts that are contributing and driving the degradation of the natural environment. In their attempt to counter these issues, big corporates are using shortcuts, such as toxic additives, that are far from the best solution.

Rather than relying solely on additives like Bovaer, there are alternatives in the shape of other innovative approaches. Some examples which show promise include:

• Seaweed Additives: Australian company Rumin8, funded by Bill Gates, claims red seaweed extracts can cut methane emissions by 80%. Research into other types of seaweed is ongoing

• Probiotics: Multistrain probiotic formulations have shown potential in reducing emissions
• Microbial Conversion: Bacterial strains have been found to convert methane into organic acids
• Essential Oils and Antimicrobials: Emerging research suggests these may also reduce emissions.

Regenerative farming, which improves soil health, captures carbon naturally, and boosts biodiversity, offers a holistic alternative. Without depending on any newly patented technology, ‘regen ag’ addresses the root causes of agricultural emissions, protects and restores the natural environment without resorting to industrial shortcuts that may create major ecological imbalances.

In the race to reduce methane emissions from livestock, the ethics, safety, and efficacy of interventions such as Bovaer have been glossed over. While the additive offers a short-term solution, long-term impacts on animals, ecosystems, farmers, meat and dairy products and human health remain unclear.

It is our view at ANH that a balanced approach—one that integrates innovative solutions that work with, rather than against nature, using sustainable and regenerative farming practices—may ultimately prove more effective and safer both for humans and the planet.

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