Seaweed in Cow Feed Reduces Methane Emissions Almost Entirely

Led by Professor of Aquaculture Rocky De Nys, researchers found an addition of less than 2 percent dried seaweed to a cow’s diet can reduce methane emissions by 99 percent.

The study was conducted in collaboration with the Commonwealth Scientific and Industrial Research Organization (CSIRO), an Australian federal research agency.

Methane is about 25-times more potent than carbon dioxide in a 100-year time span, and a single cow releases between 70 and 120 kilograms of methane per year. Burps from cows account for 26 percent of the United States’ total methane emissions, and the U.S. is only the world’s fourth-largest producer of cattle, behind China, Brazil, and India. There are currently approximately 1.3 to 1.5 billion cowsroaming the planet.

Researchers started investigating the potential effect of seaweed on cows in 2005, when a dairy farmer named Joe Dorgan inadvertently conducted an experiment on his herd in Prince Edward Island, Canada. Dorgan noticed cows that grazed on washed-up seaweed in paddocks along the shore were healthier and more productive than those that stayed in the field. He began feeding his cows a mixture of local storm-tossed seaweed and found the new diet saved him money and induced “rip-roaring heats,” or longer cycles of reproductive activity.

Dorgan is not the first farmer to discover the beneficial properties of seaweed in farm animals. The practice was used by Ancient Greeks in 100 B.C, according to the U.N. Food and Agriculture Organization. There are also records of Icelandic farmers using kelp and algae to keep livestock healthy and produce larger milk yields.

A 2014 study by Canadian researchers Rob Kinley and Alan Fredeen confirmed the results of Dorgan’s experiment and found, in addition, that “feeding seaweeds and macroalgal products has been shown to reduce enteric methane emission from rumen fermentation.” In short, seaweed can reduce the amount of methane cows emit into the atmosphere with their gas. Kinley joined De Nys in Australia two years later to conduct further in vitro tests.

Kinley and De Nys tested 20 different species of seaweed on bacteria found in the stomachs of cows. They discovered seaweed reduced methane production by up to 50 percent, depending on the amount administered. But methane reduction at notable levels required high doses of seaweed, almost 20 percent by weight of the sample. This large percentage of seaweed would be difficult to implement outside of the lab and would likely have a negative effect on cow’s digestion.

When the researchers tested a species of red algae called Asparagopsis taxiformis that grows off the coast of Queensland, Australia, they found it reduced methane production by more than 99 percent in the lab. In addition, it only required a dose of less than 2 percent to work effectively. Upon digestion, Asparagopsis produces a compound called Bromoform (CHBR3), which interacts with enzymes in ruminant stomachs and halts the cycle of methane production before the gas is released into the atmosphere.

In 2011, Dorgan sold his dairy farm in order to start selling seaweed-infused cow feed full-time. The company he part-owns, North Atlantic Organics, uses traditional methods of seaweed production like hand-raking and solar drying to reduce its carbon footprint and ensure the final product is free of additives.

However, researchers and farmers will have to overcome considerable roadblocks before the technique can be implemented on an industrial scale. Most dairy and cattle operations are located inland, far from the sea and its supply of seaweed. More importantly, producing enough Asparagopsis to feed even 10 percent of Australia’s feedlot and dairy cattle would require upwards of 15,000 acres of commercial seaweed farms. Wild harvesting could work on a farm-by-farm basis, but the practice becomes unfeasible on a large scale.




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