A type of seaweed called Asparagopsis taxiformis (A. taxiformis) could be pivotal in combating climate change by significantly reducing the methane greenhouse gas emissions exhaled by cows. But experts at Wageningen University (WUR) in the Netherlands warn that this “promising solution” could pose risks to animal health and food safety. 

The species of red algae contain high concentrations of bromoform, a substance that counteracts the formation of methane in the cow’s rumen when fed to the animal.

“But bromoform is also toxic in high doses,” says Wouter Muizelaar, a researcher at Wageningen Livestock Research, who investigated the impacts of A. taxiformis on cows after previous research linked the consumption of the seaweed to abnormalities in the rumen wall of sheep. 

The rumen wall of some of the cows was examined, revealing abnormalities and signs of inflammation similar to the studied sheep.

“Our research shows that bromoform from A. taxiformis can end up in milk and urine, which is a clear indication to reconsider whether it is desirable to feed this type of seaweed to cows,” explains Muizelaar.

“Bromoform in its pure form is harmful to health – previous research has already shown this. It is not without reason that there are limits for the maximum amount of bromoform in drinking water.”

“There are no such limits for food or animal feed, and the fact that the substance can now also be found in the milk is extra worrying. Food safety must always be above any form of doubt.”

The researcher stresses that no milk containing bromoform from the study ended up in supermarkets and that, although the seaweed can reduce methane emissions from cows, further research is needed to ensure safety for cows and consumers.

Seaweed for sustainability
There are many different species of seaweed: some experts suggest more than 10,000. According to Muizelaar, researchers have only just started to scratch the surface of how seaweed can reduce the enteric methane emission of livestock.

“There is not only a large amount of seaweed species, but they also have a lot of different compounds. Several of these compounds can in theory reduce enteric methane emission to a larger or smaller extent, but they still have to be proven practically,” he tells FoodIngredientsFirst.

“If we know what seaweed species and compounds can reduce enteric methane emissions, it might help us to find new ways to reduce these emissions. Right now, only two closely related seaweed species have shown a significant effect on reducing the enteric methane emission of livestock: A. taxiformis and A. armata.”

“Many different products are being researched by several companies, one proving more effective than the other, but it will be pivotal if we can find other compounds in other seaweed species.”

Commercialization challenges
The life cycle of Asparagopsis seaweed is complex, making the production of a high-quality supply challenging. The processing of the seaweed and ensuring that the halogenated compounds stay in the product that is eventually fed to the animals are further challenges.

“Many steps have already been taken, and improvements have been made toward overcoming these challenges, but not everything is solved yet to implement production fully. The question is also what will the eventual product price be and is that affordable?” says Muizelaar.

“The risks are that bromoform and other halogenated compounds can escape into the environment due to their volatile nature somewher in the production process. This issue will make the product less effective, and experts have also questioned if this might be harmful to the environment.”

“There has been a discussion around whether the amount of Asparagopsis seaweed required to supply the world market could have a negative effect on the local ocean ecosystem and if the amount of halogenated compounds that might be released might affect the ozone layer. These are relevant questions and should be further debated.”

WUR has been researching ways to reduce or prevent methane formation in livestock farming for several years. Notably, it is investigating what measures can be taken regarding animal feed, animals, stables and manure storage on behalf of the Dutch Ministry of Agriculture, Nature and Food Quality.

“There are benefits to using non-seaweed or seaweed-based anti-methanogenic products, but ultimately it is all about safety and efficacy. If a product is not safe or effective, there is no incentive to develop it further,” concludes Muizelaar.