Scientists say that antibiotics in cattle “boost methane production in cow pats — apparently by favoring antibiotic-resistant, methane-producing organisms in the gut,” says the BBC. “The researchers say it’s proof that antibiotic use on farms has unintended, cascading effects on the environment.”
In a paper, the scientists say 1.8 times as much methane, a powerful greenhouse gas, came from antibiotic-containing manure as from cattle not treated with antibiotics. Previous studies showed little or no impact. Agriculture accounts for nearly one-third of U.S. methane emissions and 9 percent of all greenhouse gases. Livestock, especially cattle, produce methane as part of digesting feed.
One of the authors of the paper, Tobin Hammer of the University of Colorado, told the BBC, “Most methane generated by cattle is actually released as burps, and we think that antibiotics are likely to increase burped methane as well — but in this study we weren’t able to measure that directly.” Nor were researchers able to say if all antibiotics produced the same results as those in the study, Hammer said. Finally, he said, there is question if the methane emissions are outweighed by more efficient meat production.