How science is helping reduce methane emissions from cows

According to the International Energy Agency (IEA), methane has a short lifespan in the atmosphere, surviving for 7-12 years in the atmosphere, compared to hundreds of years for carbon dioxide. However, due to its potent heat-trapping ability, scientists estimate that methane is responsible for up to 30% of climate warming since the Industrial Revolution. In other words, the impact of one ton of methane over 100 years is similar to that of around 28-36 tons of CO2 over 100 years. 

This is why there is an urgent need to address methane emissions alongside CO2 emissions. Since efforts are underway to reduce dependence on fossil fuels such as coal and natural gas, scientists have turned their focus to the major source of methane emissions, animal farming. 

How much methane do cattle emit? 

Cattle are ruminants, which means they have a four-chambered stomach. They do not have the enzymes needed to digest cellulose from the food they eat. Instead, ingested plant material is stored in the first chamber (the rumen), where it softens. This is then regurgitated and chewed it again to break it down further. The material then goes to the other chambers of the stomach where it undergoes a process called enteric fermentation. In this process, microorganisms (methanogens) break down sugars into simpler molecules, producing methane as a byproduct.

Contrary to popular belief, it's actually cow belching that contributes to methane emissions, not cow farts. Additionally, significant amounts of methane are generated from the settling ponds used for processing cow manure.

Estimates suggest that a single cow produces about 200 pounds (90 kg) of methane every year. Globally 1.5 billion cattle are raised for meat production alone every year resulting in emissions of nearly 300 billion pounds of methane. 

Could changing feed work? 

For many years, it was assumed that the amount of methane produced depends on the quality of feed given to the cattle. Low-quality feed, the thinking goes, contains a higher number of products that cannot be digested, resulting in more production of methane in the gut of the ruminant animal. 

EM Muhammed, a professor at the Kerala Veterinary and Animal Sciences University (KVASU) in India teamed up with Rothamsted Research in the UK to determine which type of feed can help reduce methane emissions. Over two seasons, the researchers gave cattle three types of silage — compacted grass from three different pastures: a monoculture of perennial ryegrass (PRG), a mix of PRG with 30 percent white clover, and PRG mixed with other plant species. 

Emissions when measured as average daily gain (ADG) of live weight (LW) showed that there wasn’t a significant difference between emissions from the different types of feed. They concluded that interventions to reduce methane emissions will likely not be as simplistic as changing feed.

Methane-reducing feed supplements

Since only changing feed does not result in a significant decrease in methane production, companies such as DSM-Firmenich have worked on tweaking the enzymes inside the cow gut to reduce methane production. Their feed supplement called Bovaer can be part of the daily feed of the cattle and is broken down into products that can inhibit methane-producing enzymes. 

More than 50 trials in real-world farms have confirmed that the supplement reduces emissions by up to 30 percent in dairy cows and 45 percent in beef cattle. DSM estimates that more than 67,000 tons of CO2e have been saved by the use of their product alone this year. 

Blue Ocean Barns, a Hawaii-based startup is another company working in this space. They grow red seaweed, an edible species eaten by humans in the area as part of their diet. Given alongside feed to dairy cows resulted in a reduction of methane by an average of 52%. 

Interestingly, the reduction in emissions was greater in cows that liked the seaweed, reaching 90% in some cases. In field studies, researchers also performed blind-tasting sessions to verify if the consumption of the seaweed changed the flavor of the milk produced, but none was observed. 

New Zealand-based dairy giant Fonterra has taken a probiotic approach to reducing methane. Along with AgResearch, the company has screened hundreds of organisms to find those that can inhibit methanogens and created a probiotic drink - Kowbucha, a play on the word kombucha, the fermented tea drink that has many perceived health benefits. In trials conducted in calves, the Kowbucha changed the microbiome picture of the rumen and led to a 20 percent reduction in methane emissions. 

Vaccines against methane

While feed supplements are an effective intervention to reduce methane, they also add to the total costs of feeding the cattle and so businesses are also interested in a one-shot solution to curbing emissions. One way to do this would be to vaccinate the cattle. 

Much like how the flu or COVID-19 jabs train the immune system against specific organisms, Charlestown, Massachusetts-based ArkeaBio is developing a vaccine that can target only methane-producing organisms inside the cattle gut. 

The company is working on identifying the organisms that it needs to target and is refining its vaccine so that the cattle produce the required antibodies in as few shots as possible. 

This approach could help reduce methane emissions by as much as 30% but is not commercially available yet. ArkeaBio claimed in an interview with Fast Company that, assuming minimal regulatory delays, the vaccine could be available as early as 2025 or 2026. 

Methane oxidation

If the wait for the vaccine and roll-out seems long, London-based Zelp has a solution that can be used right away. The company has developed a wearable device for cattle that not only neutralizes the exhaled methane but also collects data about the cow’s health and nutrition. 

In an email communication with Interesting Engineering, Francisco Norris, the CEO and Founder of Zelp, elaborated on the process. “Exhaled methane is routed to a catalyst stored in the halter where it is oxidized and released into the atmosphere as carbon dioxide and water. The data collected is processed in real time by the company’s proprietary artificial intelligence and machine learning algorithm providing farmers with improved livestock management strategies lowering costs as well as environmental footprint.”

Reducing meat and dairy

Another approach to reducing methane emissions from cattle is reducing our dependence on them for meat and dairy products. Plant-based alternatives for milk and meat have been introduced commercially in many places around the globe. 

Research is also ongoing to cultivate meat in laboratories through cell culture, which may become a more energy-efficient approach than growing animals. However, there is some controversy over this. A non-peer-reviewed study published earlier this year conducted an environmental impact assessment of the approach and found that it could lead to 4-25 times more emissions than conventional animal husbandry. 

Further studies in this direction are needed to reveal a clearer picture of the environmental effects. However, that is unlikely to be the only reason why people might want to stay with traditional methods. 

“Meat and dairy products are an important source of essential micronutrients, including iron, calcium, zinc, selenium, and vitamin B12, and they are deeply ingrained in cultures and lifestyles around the world,” added Norris from Zelp. “Livestock systems can also play an important role in improving biodiversity and the soil's ability to sequester carbon. That’s why Zelp is committed to finding ways to make the industry sustainable.”

“Reducing cattle numbers will definitely reduce methane,” KVASU’s Muhammed told IE. ”But it will be at the expense of compromising the availability of milk and meat. It will have a huge impact on the economy, particularly in developing countries." Estimates suggest that more than 1.3 billion people rely on the livestock industry for their livelihoods, food, and nutrition security. 

Efforts for reducing methane for such an industry do not stop at the laboratory, they also need to be integrated into daily lives, and science will need to address puzzles of livelihoods and food supply chains for these solutions to be truly effective.