A new feed trial published in the Journal of Cleaner Production finds that including Asparagopsis taxiformis (a species of red seaweed) in cattle diets leads to a dramatic reduction in enteric methane emissions. The researchers recorded a 98% reduction in enteric methane when high-grain cattle diets were supplemented with A. taxiformis at 0,2%. Though this result is encouraging for environmental reasons, the researchers also noted that Asparagopsis supplementation significantly improves productivity measures without causing negative side effects or decreasing meat quality.

Since this study’s design emulates intensive feedlot conditions, the researchers demonstrated that it was possible to essentially eliminate enteric methane in a greenhouse gas-intensive production system. The researchers estimated that if Asparagopsis was adopted by 20% of the beef and dairy markets, it could remove up to 15% of global enteric methane emissions per year.

Despite the study’s small sample size (20 steers), the researchers are building on previous in vitro and in vivo studies of Asparagopsis that showed dramatic reductions in enteric methane from dairy cattle and sheep. Though some questions remain over inclusion levels for forage-based diets, the researchers call for investment and commercial cultivation of A. taxiformis. The seaweed is the most promising ruminant antimethanogenic agent to date – adopting it could help cattle production move past emissions targets and into carbon neutrality.

Benefits of Asparagopsis

This trial demonstrates that producers do not need to use high concentrations of Asparagopsis to gain unprecedented methane mitigation. The low dose also elicits production benefits such as improved weight gain and rumen function, making a strong case for its adoption.

If red seaweed supplementation is widely adopted in intensive feedlot cattle, producers could see near-zero emissions of enteric methane, providing a dramatic climate benefit. Conservative adoption estimates are also promising. If 20% of the beef and dairy market across major OECD nations began using A. taxiformis, it could remove up to 15% of global enteric methane emissions per year.

More research is needed

These results should not be viewed as a magic bullet – some unknowns remain on the seaweed side of the equation. To begin, researchers still need to determine the optimal inclusion level for Asparagopsis in cattle feed. Though this trial brings us closer to the mark, it needs to be replicated to ensure we reap the most benefit from supplementation. Researchers also need to devise methods to standardise bromoform content between samples of seaweed.

From a biological perspective, researchers need to track the trace elements that can accumulate in seaweeds and see if the dietary benefits of Asparagopsis last beyond 90 days. Longer feed trials that measure cumulative intake levels will show researchers if the positive effects of supplementation have limitations or are part of a wider trend.

Researchers also need to see if A. taxiformis can be included in forage-based production systems. Existing evidence suggests that the differences in fibre content between grain and forage diets will influence the amount of seaweed needed to see dramatic methane reductions. It could be that Asparagopsis supplementation is more feasible in feedlot conditions and uneconomical for grazing cattle.

Despite these unknowns, the researchers call for investment in commercial A. taxiformis cultivation. Its introduction to the market could revolutionise cattle production, making it more efficient and environmentally sound. Read the full research paper in the Journal of Cleaner Production. – The Dairy Site