The world has a lot of cows—more than 1.5 billion. And every day, US slaughterhouses turn nearly 20,000 of them into steaks, hamburgers, and roast beef. But before they become patty-worthy, each cow spends a lifetime chewing grub and burping greenhouse gases.
Welcome to the world of belching bovines. Livestock emit 14.5 percent of all greenhouse gas emissions each year. Most of that is from cows. And because it’s pretty unlikely people will quit eating beef (or require each steer be outfitted with a fart-busting diaper), scientists around the world are manipulating the things cows eat in efforts to get cattle to stop eructing so much.
Methane doesn’t linger in the atmosphere as long as carbon dioxide—only about 20 years—but it has a much larger short-term climate impact. “Methane can trap solar heat 28 times better than CO2 can,” says Frank Mitloehner, an agricultural emissions researcher at UC Davis. Cow stomachs are four-chambered systems. The methane producing part—called the rumen—is a massive cavity capable of holding a bathtub’s worth of saliva and cud. This chewed-up muck is called roughage. Humans get a lot of their fiber from indigestible plant-based foods. Cows can digest these plants, thanks to gut microbes called methanogens that turn plant matter into fiber (which leaves the body as poop) and methane (which leaves the body as burp or flatulent).
Get rid of—or go around—the methanogens, and the methane goes, too. So the central question for fart-busting biologists is how to shift rumen’s microbial ecology without losing the benefits those little buggers provide (namely, producing the fatty acids that give beef its robust flavor).
In Australia, scientists are using seaweed. Bromoform, a compound found in kelp, blocks methane byproduct but still allows the bovines to burp. So a team of researchers at James Cook University and the sustainable farming organization CSIRO Agriculture fed seaweed to synthesized cow stomachs, then attached gas production monitors to see whether the algae diminished or escalated methane emissions. “At low levels, red seaweed—less than 2 percent of feed intake—can dramatically reduce methane emissions, cutting it back by 10 to 20 percent,” says Rob Kinley, a CSIRO researcher.
Cows love grass. So scientists at Aarhus University in Denmark are engineering “super grass” they hope can cut methane without starving the cows of other vital nutrients. Through genetic selection, they’re looking for DNA in fodder that could be engineered to yield less gas build up in the rumen.
Or, if not grass, how about meddling directly with the gut itself? Last year, a crew of Penn State researchers began adding 3-nitrooxypropanol, or 3NOP, into cow feed. Cows still get to burp, but the 3NOP binds enzymes to the bovine’s gut and prevents the gut microbes from producing methane. In experiments, cows with altered guts emitted 30 percent less gas than usual.
The problem is, these fixes only work for a short while before the cow’s gut microbiology swings back to its usual, methane producing ways. This can take anywhere from a day to a few weeks or months, depending on the cow and the method, says Mitloehner.
So far, the best solutions seem to be the least humane. Like feeding the cattle corn. Sure, it makes for sicker cows (and worse meat), but corn doesn’t have a lot of fiber. This starves the methanogens of their precious roughage. Also, corn-fed cattle don’t live as long as their grass-fed counterparts. Can’t fart when you’re dead.
Factory farms are horrendous, but their bulk ’em up, kill ’em sooner ethos results in a smaller per-animal environmental footprint. “Our animals have become very efficient, just like our cars have become more efficient,” says Mitloehner. But most beef cattle start off on rangeland, consuming grass till they’re about 700 pounds. (They’re transported to corn-finished packing plants and plumped to about 1,200 pounds by time of slaughter.) As for dairy cows, their diet for life consists of half grass and half concentrate feeds, like corn—so their carbon footprint is even higher than the hamburger heifers.
So until the bioengineering solutions work out, it’ll be a while before you’re able to order a quarter pounder—hold the planet-warming cow burps.