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Feeding Cows Antibiotics Could Be Much Worse Than We Thought

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We’ve heard a lot about how stuffing cows full of antibiotics is accelerating the superbug apocalypse. That alone should convince us to stop, but if you needed more evidence, here’s another dirty secret: antibiotics could be making cows gassier and boosting their contribution to global warming.

That’s the conclusion of a new study, which looked at the impact of a three-day course of the antibiotic tetracycline on the amount of heat-trapping methane released from cow dung. Overall, the researchers found that antibiotics upped the methane footprint of dung by an average of 80 percent over poo from cattle that weren’t fed drugs.

The increase, the researchers say, is likely due to an alteration in the microbial community found inside the cow’s ruminant (grass-digesting) stomach and inside cow dung. Antibiotics are known to wreak havoc on gut flora, and in this case, the outcome appears to be a relative increase in the number of methane-producing microbes.


The study is the first to point out a connection between antibiotics, which are fed to cows preventatively so that we can pack them closer together, and methane. And that could be a serious concern for our planet. Ruminants, including cows, sheep, and goats, release approximately 100 tons of methane each year burping, farting, and shitting. With 80 times the global warming potency of CO2, all that methane goes a long way toward cranking up the heat in our atmosphere.

More studies will be needed to confirm the connection for longer courses of antibiotics. But hopefully, between this line of research and efforts to stamp out cow farts entirely, global warming-by-flatulence is one planetary problem we’ll soon have under control.


[Proceedings of the Royal Society B via Science News]