Bovaer Backlash: Danish Cows Collapsing Under Mandatory Methane-Reducing Additive

Photo by Sebastian Marx on Unsplash

Since October 1, 2025, when many Danish dairy farmers began incorporating the synthetic additive Bovaer (containing 3-nitrooxypropanol) into their cows’ feed—alarming reports have come in of animals suffering from: stomach cramps, fevers, miscarriages, drastic drops in milk production, sudden collapses and in some cases, the need to euthanize cows.

Marketed as a “climate-friendly” methane reducer, this product—produced by the Dutch-Swiss giant DSM-Firmenich—became a legal requirement for Danish dairy farmers to be added into the feed for 80 days, or be feed extra fat throughout the year.

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Notably, farmers experimenting by removing Bovaer saw their herds recover rapidly, only for symptoms to return upon reintroduction. Yet, despite these red flags, authorities insist on pushing ahead, with an investigation only now underway.

These reports build on the concerns I outlined in my November 2024 investigation into Arla’s UK trials, where EFSA tolerance studies highlighted issues such as reduced feed intake, decreased organ weights (including ovaries and heart), and altered enzyme levels in cows at elevated doses—yet these effects were ultimately classified as “non-adverse” by regulators.

What was even more troubling were the findings from my analysis of the safety assessment report, prepared by the UK’s Food Standards Agency (FSA) and Food Standards Scotland (FSS), reviewed by Animal Feed and Feed Additives Joint Expert Group (AFFAJEG) and the Advisory Committee on Animal Feedingstuffs (ACAF).

It stated: “In relation to safety studies for the consumer, a 2-year carcinogenicity study in Wistar rats showed “mesenchymal cell tumours were reported in 4 out of 49 females at the top dose of 300 mg/kg bw/day of 3-NOP given orally. Based on these results, the original study report concluded there was evidence of carcinogenicity in female rats.”

AFFAJEG noted potential for mesenchymal cell hyperplasia and benign tumours at high doses but, citing no malignant tumours or genotoxicity, concluded the additive is not carcinogenic at recommended inclusion rates.

ACAF echoed that the additive “can be considered safe for consumers.” Yet, their conclusion was seemingly contradicted by the following statement: “The additive should be considered corrosive to the eyes, a skin irritant and potentially harmful by inhalation.”

In a separate development, a May 2024 FDA letter addressed to Elanco US, Inc, (which has an agreement with DSM-Firmenich to market Bovaer) stated: “Based on a review of your data and the characteristics of your product, FDA has no questions at this time regarding whether Bovaer® 10 will achieve its intended effect and is expected to pose low risk to humans or animals under the conditions of its intended use.”

Ironically, the FDA letter included an attachment with the following warning:

It should be noted that Bovaer passed the FDA review in under 12 months—much shorter than industry standard.

Kjartan Poulsen, chairman of the National Association of Danish Dairy Producers, has received numerous calls from concerned farmers. “We have so many people who call us and are unhappy about what is happening in their herds,” he shared with TV 2.

He described the recurring issues as unusual and is urging reports of suspected Bovaer-linked miscarriages. Poulsen emphasized that any animal harm undermines the additive’s purpose: “This should give a climate effect – and if cows die from this, or they produce less milk, then the effect is minus.” He is calling for a temporary pause from Agriculture Minister Jacob Jensen and for farmers to cease use if welfare issues arise.

Approved by the European Commission in 2022 based on EFSA assessments, Bovaer was deemed safe for cows, consumers, and the environment, with claims of up to 30-45% methane reduction.

However, field experiences differ. Reports from Jyllands-Posten and TV 2 describe lower milk yields tied to miscarriages, plus collapses—some cows recovering with treatment but others needing to be euthanized.

Earlier whispers from Danish farmers included fevers, diarrhoea, mastitis, and even cow deaths attributed to Bovaer. One producer lost six animals in under a month. Critics label it “animal cruelty,” especially under mandatory use for farms with over 50 cows.

The Danish Veterinary and Food Administration acknowledges these reports and has enlisted Aarhus University to analyse real-world data, with initial findings expected after the 2025-26 new year.

The irony is stark: a product meant to “save the planet” for reducing methane is harmful to dairy herds, slashing productivity, and raising fears of contaminating the food chain—despite assurances it “breaks down fully” with no residues.

Yet, the true winners emerge clearly: DSM-Firmenich, cashing in on booming sales fueled by mandates and climate subsidies, alongside powerhouse investors like BlackRock (holding ~3.3%) and Vanguard, who reap the rewards from this relentless net-zero drive.

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