A diet that contains small amounts of seaweed will reduce methane emissions from belching cows – by 80%.This unexpected solution is explored in the preliminary findings of a study from Penn State University. The research revolves around the lush, reddish fronds of a seaweed species called Asparagopsis taxiformis – also known as red asparagus algae – which grows in tropical and temperate seas. The study found that when dried, ground up, and added to the feed of dairy cows in tiny quantities – making up just 0.5% of the feed, overall – the seaweed cut out the majority of the methane emissions that cows emit through burping, the primary origin of this harmful gas in livestock. The altered feed had no impact on the cows’ lactation, nor the amount of milk they produced. However, when seaweed was included at slightly higher quantities of 0.75% overall, the researchers did notice a slight drop in milk yield, as well as the consumption of feed – presumably because cows did not enjoy the more noticeably fishy taste.Thus, a seaweed quantity of 0.5% in feed appears to be the optimal amount for both reducing emissions, and maintaining milk yields, the researchers suggest.Cattle contribute the largest share of livestock’s overall greenhouse gas emissions – which produce almost 15 percent of anthropogenic emissions globally. Methane makes up almost half of these emissions, which is especially worrying because it’s a more potent gas than carbon dioxide. However, its effects don’t linger for as long, meaning that efforts to reign in methane production now could have huge climate benefits in the future.The Penn research – still in its early stages, and based on a very small sample of cows – nevertheless adds to a growing body of research that highlights this unassuming seaweed as a possible pathway to less-impactful beef. Otherstudies have revealed that including even higher amounts of the seaweed in cow diets could almost completely eradicate the presence of this belched gas. The seaweed’s secret lies in a compound it contains, called bromoform, which disrupts the enzymes that produce methane in the cow’s gut. The researchers on the new study do, however, have as few concerns. Mainly, they note the shortcomings of their work – namely, that emissions were only sampled from a few cows over a few days. A fuller study would be needed to detect whether the microbes in cow rumens – which are very adaptable – possibly override the beneficial effects of the seaweed-infused feed over time. But the biggest caveat of these findings is that if seaweed is indeed a solution to livestock methane, then we’ll need to ensure that our quest for this resource doesn’t itself trigger environmental destruction. “To be used as a feed additive on a large scale, the seaweed would have to be cultivated in aquaculture operations,” the researchers note – and with all the problems already entwined with aquaculture, we’d have to be very mindful about how to do this sustainably.Seeing the potential, many are already tackling this challenge. Researchers are currently trying to maximise the growth of the seaweed, as well as the quantity of the bromoform compound it contains. And new companies like Greener Grazing and Symbrosia are now developing ways to grow this seaweed sustainably using aquaculture. The Penn State researchers also say they will be expanding their research – which will include a taste-testing panel to ensure that the milk of the seaweed-fed cows is still palatable. Cows, meanwhile, can look forward to a diet that – albeit a little fishy – could make them less of a burden on the planet.