Feeding Seaweed Supplements to Cows Cuts Methane Emissions by 80%

When a United Kingdom supermarket chain recently pledged that 100% of the British farms that supply it would be net-zero by 2030, it wasn't surprising that it suggested starting with eggs. Nor was it surprising that net-zero beef was going to take quite a bit longer to achieve. That’s because cattle farming is a potent source of greenhouse gas emissions and methane emissions in particular.

Despite recent plant-based meat trends, however, beef continues to be widely popular. So it stands to reason that we should be seeking ways to make cattle farming less damaging, even as we also work to reduce demand.

Seaweed-based feed supplements have been floated for a long time as one of the potential solutions to this gaseous problem – they’ve shown promise in both reducing methane emissions and also increasing the efficiency with which cattle turn feed into muscle mass. (With apologies to vegans, the efficiency of turning grass or corn into meat will have a big impact on meat’s overall footprint.)

Now peer-reviewed research published in the journal Plos One provides some hard numbers on exactly how much methane could be saved over an extended period of time, and the numbers are impressive. Conducted by agricultural scientist Ermias Kebreab, director of the World Food Center, and PhD student Breanna Roque, the study randomly split 21 Angus-Hereford beef steers into three different feed groups.

Each group received a regular diet that varied the amount of forage over the course of five months in an attempt to replicate the different life-stage diets of beef cattle. While one group received zero additives, the other two groups received a supplement of either 0.25% (low) or 0.5% (high) of a red macroalgae (seaweed) called Asparagopsis taxiformis. The results of that study found a huge reduction (69.8% for the low supplement group, 80% for high) in methane, as well as a modest 7-14% increase in feed conversion efficiencies (FCE). 

Of course, any solution needs to be assessed not just for the positives – but for potential drawbacks too. Is there a danger that we solve methane emissions from cattle, only to create new problems for our already over-taxed oceans? Fortunately, there’s quite a lot of evidence to suggest that seaweed farming can not only be done with minimal damage to oceans but may also help to reverse ecosystem damage that’s already taking place, like acidification, for example, or loss of marine habitat.

The current supply of A. taxiformis is mostly wild-harvested (it is also a key ingredient in Hawaiian cuisine). Given the tremendous scale of the global beef and dairy industry, there is no way that foraged supplements could put even a small dent in the methane problem. And that’s why the report’s authors conclude with the importance of developing sustainable, scalable cultivation techniques for this potentially powerful tool in the fight against climate change:

"Next steps for the use of Asparagopsis as a feed-additive would be to develop aquaculture techniques in ocean and land-based systems globally, each addressing local challenges to produce a consistent and high-quality product. Processing techniques are evolving with the aim of stabilizing as feed supplement and the economics of the supply chain. The techniques include utilization of already fed components as carriers and formats such as suspensions in oil which may be done using fresh or dried seaweed, and options in typical feed formulations such as mixtures are being explored. Transportation of the processed or unprocessed seaweed should be kept to a minimum, so cultivation in the region of use is recommended specially to avoid long-haul shipping."

For anyone having a hard time contemplating a complete abandonment of red meat, this research should be encouraging. Of course, it leaves many other ethical questions about meat-eating unanswered. But the world eats a lot of beef – and as the authors conclude, this has the potential to "transform beef production into a more environmentally sustainable red meat industry" – an important step as our culture gradually shifts to a more plant-based norm.