Digital Studios. If you grew up in suburbia like me, you might
not have ever considered the fact that cows are pretty gassy creatures. Just ask the German farmer who in 2014 had
to deal with a slight exploding shed problem, thanks to his dairy cattles burps. Turns out the thing that exploded was methane--aka
the natural gas that you might use to cook your food.
And Bessie over here, can belch up something
like 200 to 600 liters of the stuff every single day. Methane is a product of the crazy digestive
system cows have--with four, yea four, stomachs. Stomach number one is called the rumen, and
its home to a microbe zoo. From protozoans to archaeans, you can find
practically every major kind of life in there.
Why? Cellulose, the carbohydrate that makes plants
tough and fibrous, is technically impossible for the cow to digest on its own. Which is why it needs the help of all those
little microbe friends. Some of them take the cellulose and break
it down into less complex molecules that the cows can then digest. The microbes release hydrogen gas and carbon
dioxide as waste products.
That hydrogen gas, if it were allowed to build
up, could interfere with further digestion, because its actually toxic to the microbes. So another group of microbes called methanogens
take the hydrogen and react it with CO2 to produce methane. The breakdown of cellulose is more efficient
when methanogens snap up that H2 right away. The cow cant use the methane, so it just
burps it out.
Which means it loses up to 10% of the energy
present in whatever grass or plant stuff it just ate. But its kinda amazing that it gets energy
from cellulose at all--thanks to that microbe zoo. Improperly ventilated barns aside, the real
reason to be worried about cow burps is that methane is a nasty greenhouse gas. Over a period of 100 years, one kilogram of
methane could potentially warm the Earth about 28 times as much as a kilogram of CO2.
And cows, along with other livestock, emit
many many kilograms of methane from their burps -- about this many in 2007. Thats enough to make up about 7% of ALL
greenhouse gases emitted by human activities. The planet is paying a high price for our
burgers and shakes. So what can we do to save us from ourselves? There are a couple of options: either cut
down the amount of methane the cows produce in the first place, or find a way to capture
and use it.
People are experimenting with adorable backpacks
to collect cows gassy emissions. And while this strategy isnt widespread
yet, enough methane has been collected to power an experimental city bus or two. But its probably more efficient to stop
the burps in the first place. And scientists have tried pretty much everything,
with mixed results.
One approach has been to vaccinate the cows
against their own gut microbes, persuading their immune system to straight up murder
the methanogens. Researchers have also supplemented cows
feed with essential oils like garlic, peppermint, and eucalyptus to aid their digestion. And because the amount of methane a cow produces
seems to be inherited, some researchers are on the hunt for a breeding fix, breathalyzing
cows to see whos got the least methane on their breath and sending the clean ones
off to have babies. So theres no shortage of creative solutions,
once we can actually put them into action.
Until then, enjoy your gassy half-pints and
exploding barns. Thank you to CuriosityStream for supporting
PBS Digital Studios. CuriosityStream is a subscription streaming
service that offers documentaries and nonfiction titles from some of the world's best filmmakers,
including exclusive originals. We're all big fans of Sir David Attenborough
around here, especially when he talks chemistry, so David Attenboroughs Light on Earth
is one we highly to recommend.
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