Livestock farming is a major source of greenhouse gas emissions worldwide because ruminants like sheep and cattle produce methane as a byproduct of digestion.
Supplementing the diet of beef cattle with red seaweed can more than halve methane emissions without compromising meat quality, according to a study, publishing March 17, 2021 in the open-access journal PLOS ONE, by Breanna Roque from the University of California and colleagues.
The researchers fed twenty-one Angus-Hereford beef bullocks their usual diet of hay, grains, and corn, supplemented with either zero, low, or high concentrations of red seaweed (Asparagopsis taxiformis).
They measured the quantity of methane, hydrogen, and carbon dioxide released by individual bullocks periodically for 21 weeks and found that seaweed supplements reduced methane emissions by between 45 percent and 68 percent.
The proportion of forage in the base diet also influenced emissions; the greatest reductions were found with a high seaweed-supplemented, low-forage diet, which reduced methane production by as much as 80%. Professional grading and consumer testing revealed no effect on the quality or flavor of the meat.
The study is the first to show a sustained reduction in cattle greenhouse gas emissions as a result of feed supplementation. Bullocks also sustained normal growth rates while consuming less food, suggesting that red seaweed supplemented diets could help farmers improve efficiency, reduce costs, and reduce methane emissions simultaneously, the authors say.
There is more work to be done, but we are very encouraged by these results. We now have a clear answer to the question of whether seaweed supplements can sustainably reduce livestock methane emissions and its long-term effectiveness."
Breanna Roque, University of California
Roque, B. M., et al. (2021) Red seaweed (Asparagopsis taxiformis) supplementation reduces enteric methane by over 80 percent in beef steers. PLOS ONE. doi.org/10.1371/journal.pone.0247820.