Methane Emissions from Cattle: How Diet Can Help Reduce Climate Change

Wednesday - November 1 2023, 11:10 UTC - 1 year ago

In order to tackle climate change, countries have pledged to reduce carbon emissions to net zero. While it's mainly focused on CO2, methane is a more potent greenhouse gas than carbon dioxide. Animal farming is responsible for most major sources of methane, mostly generated from a cow's stomach and belching. Feeding cattle with high-starch diets or certain combinations of food have been found to be helpful in reducing methane emissions.

In the fight against climate change, countries around the world have taken the pledge to reduce their carbon emissions to ‘net zero’ in the near future. To this effect, there are growing efforts to electrify transportation and industry and generate electricity from renewable sources.

While the focus has largely been on reducing carbon dioxide emissions, less attention has been paid to the question of methane, which is a more potent greenhouse gas. According to the US Environmental Protection Agency (EPA), methane accounts for 20 percent of global greenhouse gases but traps 25 times as much heat as carbon dioxide.

Where does methane come from? .

Methane, or CH4, is a hydrocarbon. One major source of methane emissions is as a byproduct of the coal production process. Another is agriculture, where livestock farming accounts for nearly a third of methane emissions.

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 deterine how much of an effect feed can really have on reducing methane emissions from cattle.

The surveyed around 4,500 cows in India and changed the feed for them in order to test the effect on methane emissions. Feed with different kinds of food were tested, including feed that had elements of pineapple leaves, barley, lantana, oil cakes, and vegetables.

Their experiments revealed that the cows that were fed diets high in starch produced less methane than those who were fed diets low in starch. But that’s not all – they found that some feed regimens resulted in an overall no net change in emissions, leading the researchers to conclude that certain feed combinations were ‘neutral’ in terms of methane production.