The owner of Danish butter brand Lurpak has defended its recently-announced trial to add a methane-suppressing supplement into cow feed as calls to boycott the brand continue.

Arla Foods, which owns the UK’s biggest dairy co-operative, announced the initiative aimed at tackling climate-heating methane emissions produced by cows during digestion.

The firm is working alongside Morrisons, Aldi and Tesco on the project, which will trial the use of feed additive Bovaer across 30 British farms.

Research suggests the supplement can reduce methane emissions from cows’ digestion by an average of 27%, but questions remain over such additives’ long-term effectiveness and impact on animal health and welfare.

Swathes of British shoppers on Friday joined an online storm calling for a boycott of Arla brands, especially Lurpak, with several accusing it of going “woke”.

“Just chucked my Lurpak in the bin,” one user wrote on X, formerly Twitter.

Another said: “Happy to consume dairy products from smaller, independent farms who are not party to these mad practices.”

Many said the additive was being put into the milk itself – rather than into the feed of the cows producing it – and others implied that tech billionaire Bill Gates is involved.

One user wrote: “I’ve used Lurpak for years. I’m not prepared to further them anymore if they are adding this chemical to milk which they use to make their product it’s completely wrong on all levels in my view forcing this on us.”

Another said: “@Lurpak I used to buy your product but will now stop since you are now using Bill Gates poison in your foods.”

The Microsoft co-founder is not involved in the Arla trial, or Bovaer more widely, but last year invested millions into a rival start-up Rumin 8, which develops similar additives.

An Arla spokesperson said the health and safety of consumers and animals is the firm’s “number one priority”.

“The information spreading online surrounding our link to Bill Gates is completely false and claims relating to his involvement in our products is inaccurate,” they told the Grocer.

“Bovaer has already been extensively and safely used across Europe and at no point during the trial will there be any impact on the milk we produce as it does not pass from the cow into the milk,” the spokesperson insisted.

“Regulatory bodies, such as the European Food Safety Authority (EFSA) and UK Food Standards Agency, have approved its use based on evidence that it does not harm the animals or negatively impact their health, productivity, or the quality of milk.”

Bovaer was authorised in the UK in April and has been approved for use in a number of countries, including EU countries, Australia and Canada.

The Food Standards Agency (FSA) said all authorised feed additives, including Bovaer, have undergone its rigorous safety assessment, which is part of a wider process to ensure products are safe and appropriate for the UK market.

It added that its top priority is is protecting consumer interests and holding up food and feed standards when considering any regulated product.

Arla’s trial aims to explore how methane-suppressing feed additives could be rolled out across a larger group of farmers in the UK and is part of the firm’s wider commitment to reduce the environmental impact of its dairy production.

Paul Dover, UK agricultural director at Arla Foods, said: “We know that reducing methane is a big opportunity when it comes to improving our carbon footprint at farm level and feed additives like Bovaer have huge potential in helping us tackle this issue.”

Mr Dover said rolling out the additive at scale will “not be easy due to the cost involved”.

He added: “(So) it’s important we understand more about their usage potential and then work together with the industry, government and our partners to support farmers if we want to harness the opportunity they present in driving down emissions.”

National Farmers’ Union dairy board chair Paul Tompkins said: “While FSA-approved products could be useful tools in helping to reduce methane emissions, questions remain about long-term efficacy, that it can be used practically and effectively on farm, and that animal health and welfare will not be impacted.”

He said Government research shows shoppers are generally positive about the products as long as human and animal health are not affected.

“It’s critical we also have a strong evidence base to give farmers the confidence to use these products. This trial project between Arla, Morrisons, Aldi and Tesco could help provide this evidence,” he added.