Seaweed has long been touted as a human “superfood” but more attention has recently turned to its possible use as a feed additive to reduce methane emissions from ruminant livestock, particularly cows. Headlines have claimed as much as -80% reductions in the amount of methane released by cow burps. I know, like me you are probably laughing but this is the world we now live in.
The good news… seaweed apparently inhibits an enzyme in the cow’s digestive system that contributes to methane production. While the biggest reduction numbers come mostly from studies conducted in laboratories, some on-farm trials have also shown results significant enough to justify a deeper look. And what might be a big bonus, studies are showing steers converting feed to body weight up to 20% more efficiently than cattle on a conventional diet. It’s not entirely clear why but previous research has suggested that some rumen microorganisms can use hydrogen that is no longer going into methane production to generate energy-dense nutrients that the cow can then use for added growth.
Over the summer, two dozen cows at California-based Strauss Dairy were fed a few ounces of powdered asparagopsis, an edible red algae, along with their hay and alfalfa. Another 24 cows ate their regular feed as a control group. The methane emissions in the cows’ burps were measured using a device called a GreenFeed. The cows that ate the seaweed showed a -52% average reduction in methane over 50 days. A few cows had reductions of up to -90%. These same cows were also documented as converting feed to body weight up to 20% more efficiently than cattle on a conventional diet. The trial, the first on a commercial diary, was sponsored in part by Blue Ocean Barns, a company that is experimenting with growing red seaweed for use as feed.
Researchers at the University of California, Davis, found that adding as little as 3 oz. of red seaweed a day per cow to feed rations was enough to cut emissions, an amount that also can’t be detected by cows – from what I understand, they aren’t big fans of the seaweed taste. I can’t say I blame them!
On the other side of the pond, scientists at the Institute for Global Food Security (IGFS) at Queens’ University in Belfast are studying the use of brown and green seaweeds that are indigenous to the UK and Ireland. Based on lab experiments, the researchers believe the seaweed varieties could reduce methane emissions from ruminants by at least -30%. One three-year trial is now being conducted in partnership with UK supermarket chain Morrisons and its network of British beef farmers. A second trial is set to begin in Ireland sometime in early 2022.
Seaweed farms are now springing up off the shores of Australia, Europe, and North America as various startups seek to exploit its potential, including Blue Ocean Barns. They are very small-scale though, and their products still need regulatory approval. Keep in mind, there are big differences in the types of seaweed being used in these projects. Red seaweed grows in warmer climates, while the brown and green varieties being studied in the UK and Ireland can tolerate cooler temps.
Large-scale cultivation of seaweeds has been practiced in Asia for decades. China is the biggest producer of brown algae, mainly cultivated kelp species. Growing systems for kelp species in China and the rest of Asia are very effective. However, due to the labor-intensive nature of these systems and the low costs of such a large workforce in China, technological modifications to reduce labor costs associated with cultivation will need to be developed in emerging seaweed-producing countries.
There are also questions about the long-term efficacy of using seaweed to reduce ruminant methane emissions. Most ruminant animals tend to adapt to new feeds, which could weaken the methane-reducing effects of the seaweed over time. The active ingredients in the seaweed are also sensitive to heat and sunlight, raising questions about the shelf life.
Bottom line, there are now dozens of methane interventions for livestock under development but most are years from commercialization and have many hurdles to overcome before making a wide-spread impact on the livestock feed industry. (Sources: Drovers, The Guardian, UC Davis, PhysOrg)