The controversial quest to make cow burps less noxious

Even though the cows are fed in the shade of the large open-air structure, it's still hot in the barnyard. They would normally eat in a trough on a farm. But at UC Davis, they eat from special blue bins that track how much each animal eats. It's similar to Weight Watchers except that researchers are more interested in the cows' figures than their burping habits.
Frank Mitloehner, animal scientist, leads me to another type of feeder that could be mistakenly called a mini wood chipper. When the machine detects that a cow has entered, he grabs a few of the alfalfa-pellets. Mitloehner said that this is almost like candy for them. As Mitloehner points to a small tube of metal within the machine, I put my head in it. This probe measures how much methane the animals exhale. It happens three times per hour for all the animals.

You see, cows have serious emissions problems. Their cavernous stomachs are fermentation vats and can be used to digest difficult plant material. Their cavernous stomachs are awash with methanogens, microbes which convert cellulose into volatile fatty acids. These volatile fatty acids are then converted to meat and milk by the cows. Methane is also produced by methanogens. This greenhouse gas is 80 times more powerful than carbon dioxide due to the way that its molecules vibrate to absorb infrared light. This means that these gases trap heat and cause more global warming.


Mitloehner says that methane is a byproduct. It is not easy for cows to eat it. The plants cows eat have poor nutritional content, so they must eat lots of food in order to survive.

Multiply those burps by world's large cattle population. A billion cattle roam the earth to satisfy mankind's endless hunger for milk and beef. An international research team published a paper in Nature Food in September that found that global food systems are responsible for 35 percent of all greenhouse gas emissions. A quarter of these food emissions are caused by beef, while 8 percent come from milk production.

Methane is only stable for about a decade, while carbon dioxide can last for many centuries. Scientists could find a way to get cows to stop leaking so we would see a significant reduction in greenhouse gas emissions. Mitloehner, along with other researchers, are trying food additives such as garlic, seaweed, and essential oils derived form plants like coriander seeds. These can alter the animal's gut environment in different ways. For instance, they disrupt the enzymes that make methane. Biocharcharcoal is also being explored, which absorbs methane from the stomach.

Mitloehner has gone to great lengths to quantify the cows' diets. He uses high-tech troughs as well as snack-dispensing methane detections to show how a technique might reduce his enteric emissions. We found that depending on the additive, we can reduce your enteric emissions anywhere from 10 to 50%. That is quite remarkable, says Mitloehner.


A team led by Ermias Kbreab, an animal scientist at UC Davis, published research earlier this year that showed a reduction in gas emissions of up to 82 per cent using seaweed additives. However, scientists who have tested other additives have found lower levels of effectiveness. Wageningen University and Research in 2019 examined the organic compound 3-nitrooxypropano (or 3-NOP). It found a 50% reduction. Researchers in the UK and Switzerland discovered that Agolin, which is a combination of essential oils, reduces methane production by just 6 percent. New Zealand cows that were fed tannins saw a 13% reduction in methane production.

The logistics of adding a feed additive for the billions of cows in the world pose logistical problems. Researchers Matthew Hayek, Jan Dutkiewicz, and others wrote in WIRED earlier in the year that seaweed's benefits are unlikely to be as significant as they claim. Seaweed has the potential to reduce methane emissions from cows and can scale up to solve the problem. The researchers found that cows are most likely to produce methane when they are grazing on pasture grass, which is the hardest-to-digest material. This is where most cattle spend their entire lives. They live in feedlots where it would be simple to add nutrients to their diets. Only when they are being slaughtered, do they eat any additives? Researchers found that cows only 11 percent of their total lifetime methane is excreted during the months spent on feedlots.

Mitloehner admits that this is a problem. He says the challenge is to get them into free-range cattle who aren't fed at a trough. Salt licks or drinking water might be one way. These active ingredients are being prepared for the cow's stomach.

He also wants to avoid any side effects. He says that the higher your emissions reductions, the more likely there are for unintended consequences. To ensure that the additive doesn't affect growth, researchers must track animals' weights. They must also consider palatability, as some cows don't like garlic-flavored food. The animal may end up urinating less but the milk might taste strange. He says that we need to figure out the happy medium.