Can Scientists Create Cows That Burp Less Methane?

When my daughter was ten years old, I dared her to put her hand in the stomach of a fistulated cow–hoping she would overcome the ick factor and learn something about cow digestion. If you have never seen a fistulated cow, imagine a cow with a porthole inserted into its side, big enough to stick your hand in and feel the stomach. Why in the world would scientists insert a porthole into the side of a cow? The better to study its digestive processes—and methane emissions.

And cows do have digestive challenges. They thrive on forage with high fiber content. Fiber consists of carbohydrates like cellulose and lignins that cannot be digested by the enzymes in a mammal’s gut. So how do cows (and other ruminants like sheep, goats, buffalo, and camels) digest fiber? Actually they don’t. Instead their stomachs host an army of trillions of microbes to do the job. But in digesting the fiber, the microbes emit 30-50 quarts of gas per hour into the cow’s stomach. Feeling bloated, the cow belches the gas–which is overwhelmingly methane–to relieve the pressure. The methane enters the atmosphere where it warms the planet 82 times faster over a period of twenty years than the more prevalent greenhouse gas carbon dioxide.

So can we create cows that belch less methane? Food scientists, geneticists, microbiologists, and animal scientists are teaming up to answer this question. Here are some of their answers.

Strategies to reduce cow methane emissions

Change cattle diets

Cows eat a lot of fiber, and digesting fiber leads to a build up of methane in their stomachs. The problem lies in that much of the fiber that cows eat comes from grasses, hay, and low-cost food byproducts. Switching to grains can reduce methane build-up but can be costly for farmers. Farmers must also balance grains and fiber to fine-tune their cows’ diets for maximum health and productivity. Another problem is that much of the world’s cattle are not fed daily by humans, and we can not always ask these free-ranging cows to gather around the dinner table each day for a low-fiber meal.

Feed additives

Just when humans are questioning additives in our own foods, cows are being asked to consider consuming feed additives. You can think of additives like spices–a small portion creates a big effect. Researchers around the world are developing feed additives that reduce methane emissions while increasing or at least maintaining meat or milk production. Additives also need to be affordable and easily administered by farmers. One such additive is 3-NOP (3-nitrooxypropanol), which has been approved for use in over 65 countries under the name of Bovaer. According to its developer dsm-firmenich, “Just a quarter teaspoon per cow per day reduces methane emissions from dairy cattle by 30% and up to 45% for beef cattle, on average”. Another additive that has received widespread attention is seaweed, and its active ingredient bromoform. Although seaweed may be widely available, it is often contaminated by heavy metals, contains iodine which is toxic in high amounts, and is a possible carcinogen. Its massive harvest can also have devastating impacts on oceans. To reduce contamination and environmental impact, companies like Symbrosia and Blue Ocean Barns in the U.S., and Volta Greentech in Sweden, are culturing seaweed in large tanks on land, and claim their products are safe and reduce cow emissions from 30-90%. In Sweden, you can even buy a ground meat product “Lome” named after the feed additive. Over the next several years, scientists and farmers are watching to see whether the regulators approving seaweed and bromoform as feed additives address consumers’ health concerns.

An ongoing challenge is the cost of additives. Roughly 12 U.S. states have incentives for farmers to adopt these technologies and carbon credits are another possibility. For farmers in lower-income countries, the costs of adopting these technologies will need to be offset. This is especially challenging in places like India, where an average farmer tends only a couple cows. Professor Joseph McFadden at Cornell University (my employer) sees a future where livestock management in India is consolidated at the village level–thus reducing costs through cooperation and creating economies of scale.

Genetic Selection

A bit of good news about cows and methane is that cows eating the same amount of feed and living on the same farm produce different amounts of methane. This opens up the possibility that emissions are controlled in part by a cow’s genetics. Scientists are in fact starting to breed cows for lower methane emissions. Researchers at the University of CA-Davis think that by the end of the decade, bulls will be tested not just for how likely they are to transmit high milk production and good health to their offspring, but also for the level of methane emitted by their progeny.

Vaccines

Vaccines for humans have captured the headlines recently, but we should also be paying attention to a methane-reducing vaccine for cows. In fact, a vaccine that causes cows to produce an antibody that interferes with their gut microbes’ ability to produce methane is under development. If vaccines are administered once or infrequently, they might be a solution for cows that spend their lives grazing freely rather than confined in feedlots.

Whereas feeds and feed additives are coming onto the market rapidly, genetic selection and vaccines are probably a decade away.

Wearable devices

This idea seems a little far-fetched to me. One device is a mask over the cow’s nose, collecting burps as they’re expelled. The mask is equipped with a catalyst that oxidizes the methane into carbon dioxide and water. But even though carbon dioxide is a much weaker greenhouse gas than methane, it can stay in the atmosphere thousands of years longer. So why would we invest in a technology that creates more carbon dioxide? Another experimental technology connects tubes near the cow’s mouth. The methane burps are vacuumed up to a container on the cow’s back. But the container needs to be emptied daily, which means the farmer needs to hire lots of workers. And even though the methane collected may be used as a biofuel, I imagine methane leaking from hundreds if not thousands of containers switched out daily would be a problem.

The cow methane problem and solutions

Beef production is the largest contributor to food-related climate emissions in the U.S. Pound for pound, it generates nearly 250 times the emissions of plant-based protein like beans and lentils. And beef production is estimated at 81% of meat-related U.S. emissions. This is all because of those methane-producing microbes in the cow’s stomach. Because methane-producing microbes are absent from the guts of pigs and poultry, they emit much lower amounts of climate gases compared to cows.

Methane also helps explain why the combined annual emissions from the top five meat and dairy corporations—JBS, Tyson, Cargill, Dairy Farmers of America (DFA), and Fonterra—exceed those of Exxon. Claims by JBS that it will achieve net-zero emissions by 2040 have been challenged in a lawsuit brought by New York Attorney General Letitia James. Lawsuit or not, methane emissions from beef and dairy are only expected to grow in the absence of serious efforts to limit them, and even to exceed those of the fossil fuel industry by 2050.

No technology to reduce methane emissions is perfect. The technologies’ efficacy will vary depending on climate, soils, and cattle management practices. And technologies may need to be combined–for example, feed additives and vaccines–as well as integrated with manure management and other ways to reduce climate emissions in livestock operations.

Efficiency–that is the pounds of milk or beef per unit of feed and other inputs–tends to be lower in poorer countries relative to wealthy industrialized nations due to improved livestock breeds and management practices. Remarkably, increased efficiency in dairy management (fewer cows producing more milk) has resulted in a 41% reduction in the carbon footprint of dairy in 2007 compared with 1944. According to McFadden, one of the best things we can do is improve efficiency by introducing more efficient breeds and better animal health and nutrition. This means more milk and meat from each cow, which in turn means fewer cows and lower methane emissions to feed the same number of people. Although methane-inhibiting feed additives and other technologies to reduce methane emissions have not yet demonstrated gains in productivity, scientists are keen on finding the “sweet spot” balancing emissions reductions and productivity.

How can I help reduce cow methane emissions?

• Be open-minded to different approaches to reducing cow emissions–pasture-fed beef have lots of benefits but they may not reduce emissions compared to feedlot-raised beef.
• Support continued research and development to improve livestock management.
• If you eat a lot of meat and live in a country where meat consumption is higher than recommended, reduce red meat consumption in your daily diet and through supporting healthy food policies in schools, hospitals, and other institutions. Although cutting back on meat is not appropriate in regions where people have limited access to protein, it is an important means to reduce methane emissions in wealthy nations. In short, let’s support efforts to reduce cow emissions and modulate beef consumption appropriate for different regions around the world.

When my daughter stuck her hand in the cow’s stomach, perhaps she learned a little about the science of cow digestion. All of us need to pay attention to the important and sometimes counterintuitive science behind how cows contribute to climate change and what we can do about it.