On a remote ranch in northern Australia, some cows will soon start eating a little seaweed with their daily meals. The researchers feeding them are attempting to solve a massive problem: cow belches are the biggest source of climate emissions in agriculture. Eating seaweed may reduce methane—a potent greenhouse gas found in burps—by up to 99%.
"The seaweed has some chemicals inside it which interfere with the bacteria-producing methane," says Rocky de Nys, an aquaculture researcher at James Cook University. "So instead of the carbon going out of the stomach with a burp, the carbon can get shunted into energy production in the cow."
The research is one approach among many to make cows less gassy. In Canada, researchers are selectively breeding cows that burp less. Others are experimenting with vaccines that fight the microbes that make cows produce methane, or backpacks that cows wear to capture their gas for energy.
Many others are experimenting with plant-based supplements that can be added to cow feed to help. A byproduct of cashew nut processing, for example, can reduce emissions by 8%. If cows graze in pasture, adding plants like legumes can make them burp less. Researchers in Denmark are working on a "super grass," bred after analyzing the genetics of which grasses are easiest to digest.
But the seaweed—a species called Asparagopsis taxiformis—may be particularly promising. The Australian researchers started by creating an artificial cow stomach and testing various species of seaweed inside it.
"You basically put a little bit of a cow's stomach in a jar, and then you add a substrate, the grass that a cow would normally eat . . . then you add a sprinkle of seaweed," says de Nys. Inside the fake stomach, it's possible to quantitatively measure how much methane is produced; compared to a control, the seaweed reduced emissions 99%.
In previous experiments, the researchers tested a seaweed supplement in sheep and found that it reduced their methane emissions by up to 70%, without affecting the growth of the sheep. In trials through 2017, the researchers will study the effect of the seaweed in cows.
If it works as expected—and doesn't create any problems in milk or meat—the next challenge may be scaling up seaweed farming to supply all of the cows that could use it. Still, de Nys thinks that the industry could adapt.
"It's a very big industry," he says. "So the techniques and procedures and logistics are all in place. Really no one's farmed this seaweed because there's never been demand for this seaweed before. No one's ever said, 'Oh, can we feed this to cows to reduce methane?' until now."