Research to reduce cow methane emissions is currently underway.

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In discussions about climate change, carbon dioxide gets a lot of the attention, but about 16 percent of the greenhouse gases created by human activity consists of methane, and about one-third of those methane emissions are produced by cattle. The roughly one billion cattle grazing at any given time on the planet create about 500 liters of methane every day. Reducing that methane production would be helpful in combating global climate change.

How to do that, however, is still being puzzled out. There are a few factors that determine how much methane a cow produces, and each animal produces differing amounts. Diet and genetics are the two strongest determinants, though, as they have the greatest impact on a cow’s digestive tract. An international project called RuminOmics has been studying this issue, and they have some interesting data to report.

It turns out that the cows that produce the least methane are also the least efficient at producing milk, but cows become more efficient at using energy as they age. As such, mature cattle are better producers and those are the ones farmers might want to keep in production.

The idea of simply breeding cattle with low methane emissions isn’t all that sound, because we would need more of them to maintain production levels of milk and beef, which would kind of defeat the purpose. Instead, it seems like we want to breed the most efficient cows, and keep them working as long as we can.

In the meantime, we can also look to make changes in cattle diets that will lead them to producing less methane without losing their efficiency as milk producers.

“By changing the feed of cows, we seek to reduce the proportion of microbes causing methane emissions, the amount of which is also related to the amount of saturated fatty acids in milk,” says Johanna Vikki, a professor at Luke Natural Resources Institute in Helsinki, Finland.

In short, by breeding more climate-friendly cows, we could also have healthier milk.