Antibiotic Cow Farts Contain More Methane

Cows treated with antibiotics produce more methane when they pass wind. Dudarev Mikhail/Shutterstock
Ben Taub 25 May 2016, 16:04

The rear end of a cow can be a volatile and temperamental place at the best of times, but by treating their cattle with antibiotics, ranchers may in fact be increasing the potency of their animals’ farts. According to a new study that appears in the Proceedings of the Royal Society B, cows that receive a common course of antibiotic treatment release 80 percent more methane from their posterior portal, potentially bloating their carbon hoofprint.

Though research has shown that cows actually release more methane by burping than by farting, the environmental impact of the animals’ anal emissions is certainly not to be sniffed at. It’s therefore important that farmers adopt responsible policies when looking after the health of their herds, ensuring that they do not encourage too much of a draft down below.

To investigate how antibiotics contribute to methane emissions from cattle, researchers placed five cows on a three-day course of tetracycline, a popular antibiotic commonly used to ensure the wellbeing of farm animals. Each day, the team performed the unenviable task of collecting the cows’ manure and measuring the gas emissions given off by these pats.

Results showed that the poop produced by these cows let off 1.8 times as much methane as that of other cows that had not been treated with tetracycline.

As every farmer knows, sometimes you just have no choice but to take a look up a cow’s bottom, although since the scientists behind this research have yet to venture into the animals’ entrails, they can only speculate as to the cause of this finding. To determine the precise reason for this methane waft, it will be necessary to perform a thorough analysis of the cows’ gut microbiota both with and without antibiotics.

In the meantime, the researchers hypothesize that tetracycline allows a type of microorganism called archaea to thrive in the cows’ intestines by killing off other bacteria with which these single-celled creatures normally compete for hydrogen. Since archaea release large quantities of methane as a by-product of their metabolism, any increase in their population results in significantly beefier cow farts and cowpats.

Though the full extent of the environmental impact of treating cattle with antibiotics is not yet known, it’s clear from this study that fears about the practise contributing to greenhouse gas levels are much more than just hot air.


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