What we know about Bovaer and Danish cattle farms

"IMPORTANT: Denmark forces farmers to give a chemical to cows to stop them from farting, for climate! Now cows in Denmark are collapsing and dying due to Bovaer poisoning," a November 4, 2025 post on X claimed.

AFP was able to identify several, seemingly authentic videos from Danish farmers signaling issues with the health of their herds they claim are caused by the additive (archived here, here and here).

But panic-filled posts from unrelated accounts reshared the farmers' declarations across regions and languages on multiple platforms, as climate-skeptic accounts also amplified the claims.

Image

A screenshot of an X post taken on December 1, 2025

The videos reference a 2025 Danish mandate aimed at curbing the emissions of the meat and dairy industry. It requires farmers either integrate more fat into cows' diets or administer the compound Bovaer (archived here). 

Produced by the Swiss-Dutch company DSM-Firmenich, Bovaer uses active ingredient 3-nitrooxypropanol (3NOP) to transform the last step of a cow's digestion, essentially turning its burps into hydrogen rather than methane (archived here and here).

Methane is a particularly potent and short-lived greenhouse gas that would typically trap heat when produced by cows, thus contributing to Earth's rapid warming.

While Danish farmers have pointed to health complications in cows after introducing Bovaer into cattle feed, government and industry experts are still investigating to determine whether the reactions are connected to the compound.

Additionally, no country currently makes the use of Bovaer mandatory.

Danish regulation

Danish farmers can choose to administer Bovaer or increase fat in cattle's diet, "but Bovaer is much easier to implement," said Ermias Kebreab, associate dean for global engagement in the College of Agricultural and Environmental Sciences at the University of California, Davis (archived here).

He told AFP on November 21 that Bovaer is a widely "studied additive with over 100 papers published" and that extensive scientific evidence has shown no significant negative impacts on cattle health from integrating 3NOP in diet (archived here).

The Danish Veterinary and Food Administration said in a November 22 press release that it is monitoring the situation with its industry partners and may adjust the feed models suggested for 2026 (archived here).

Farmers are encouraged to report any health issues to the government (archived here).

SEGES Innovation, the Danish research and development firm in charge of investigating the complaints, reported that out of 644 milk-supplying herds taking the additive, 419 showed a decline in the amount of feed consumed by the animals, 434 recorded a drop in milk production and 376 reported both issues (archived here).

Updated figures for December are not yet publicly available.

"Bovaer must be mixed thoroughly and evenly in the feed ration to avoid overdosing and ensure effectiveness," said Lars Arne Hjort Nielsen, senior specialist in cattle production at SEGES Innovation (archived here), on November 25.

Widely used

Seventy countries, including Canada and the United States, currently authorize the use of Bovaer, according to DSM-Firmenich (archived here).

The company said no other countries had reported issues with its additive.

"Bovaer was used successfully in the first nine months of the year in Denmark by 400 dairy farmers, without ever being identified as a contributor to health issues in cows," a company spokesperson told AFP on November 27.

Some studies have reported reduced feed intake and lower milk in cows consuming Bovaer (archived here).

Charles Nicholson of Pennsylvania State University, who reported such effects in his research, told AFP that the changes in food intake and milk production observed do not "seem large enough to reflect or result in other health issues, at least for the average cow" (archived here and here).

University of Wisconsin-Madison's Luiz Ferraretto (archived here), a ruminant nutrition associate professor and co-author of the study, told AFP on December 5 that "3NOP has been tested extensively worldwide and no concerns about major reductions in dairy cow productivity or health were raised."

A separate study, financed by DSM-Firmenich and the regional economic development branch of the Northern Netherlands Alliance, in contrast reported an increase in milk production (archived here).

Its co-author Jan Dijkstra, associate professor in ruminant nutrition at Wageningen University (archive here), told AFP on November 21 that current scientific literature does not provide "any indication, or mechanism" on how 3NOP may cause problems like mastitis (the inflammation of breast tissue), dermatitis, or death.

In a previous statement, DSM-Firmenich said the UK Food Standards Agency, as well as the European Food Safety Authority (EFSA) had approved the additive's use "based on evidence that it does not harm the animals or negatively impact their health, productivity, or the quality of milk" (archived here).

The EFSA referred AFP to its 2021 scientific opinion, formed by an expert panel on additives, per the European Commission's request (archived here).

"Our experts concluded that Bovaer 10 is safe for dairy cows at the maximum recommended level, also representing no safety concerns for the consumers or the environment," an EFSA spokesperson told AFP in a November 26 email.

Previous unsupported claims alleged Bovaer was linked to health issues in humans.

Sector transition

Ruminant livestock -- cattle specifically -- are an important focus of mitigating emissions from human activities.

Katharine Dickson, a biomethane scientist at the University of California, Davis (archived here), said most of agriculture's "methane problem rests squarely on the back the cattle sector."

Using Bovaer to reduce methane and curb emissions provides an "industry preserving" strategy which is more easily adopted than previous approaches to feed manipulation, she said on November 25.

In contrast, Dickson said mandating people to cut the amount of meat in their diets is "extremely unlikely to be viable in a democracy with strong consumer preferences and a largely market-based food system."

AFP has investigated the impact of methane from livestock on climate change, here and here.