Supplementing the diets of grazing beef cows with seaweed in pellet form could cut their methane emissions by almost 40 percent, a new study has found.
The seaweed pellets led to this plunge in emissions without affecting the health or weight of the cows, according to the study, published on Monday in the Proceedings of the National Academy of Sciences.
Livestock are responsible for 14.5 percent of global greenhouse gas emissions, with the largest chunk stemming from the methane released by cattle when they burp, the study authors noted.
Grazing cows produce more methane than their feedlot or dairy peers because they consume more fiber from grass, the researchers explained. Across the country, there are 9 million dairy cows and 64 million beef cattle.
“Beef cattle spend only about three months in feedlots and spend most of their lives grazing on pasture and producing methane,” senior author Ermias Kebreab, an animal science professor at the University of California Davis, said in a statement.
Kebreab stressed the importance of making a seaweed additive “more accessible to grazing cattle,” with hopes of making the industry “more sustainable while meeting the global demand for meat.”
While previous studies have determined that giving seaweed to feedlot cattle and dairy cows leads to substantial cuts in methane emissions, this is the first study to evaluate the incorporation of seaweed in the diets of bovines that graze on grass.
Daily feeding of pasture-based cattle is more difficult than dairy or feedlot animals because they tend to graze far away from ranches for long periods of time, the authors noted. But during the winter when food becomes scarce, ranchers supplement their diets.
To study the effects of seaweed on the cows, the researchers divided 24 beef steers into two groups: one that received a supplement and one that didn’t. They conducted the experiment over a 10-week period at a ranch in Montana.
Even though the supplement group members were not forced to eat the additive — they consumed it voluntarily — the scientists still observed a 37.7 percent plunge in methane emissions.
Kebreab stressed the importance of their findings, given the fact that pastoral farming across large grazing networks supports millions of people around the globe. Often, however, these areas are vulnerable to the impacts of climate change.
Giving the grazing cattle a supplement in this manner could help pastoral farming persist in a more sustainable manner, according to the authors. And while the UC Davis researchers provided the seaweed supplement in pellet form, Kebreab suggested that ranchers could also give their cows the additives through other approaches, such as offering cattle a block to lick.
“This method paves the way to make a seaweed supplement easily available to grazing animals,” he added.
