Antibiotics Are No Longer Making Pigs Bigger

<a href="http://www.shutterstock.com/cat.mhtml?lang=en&language=en&ref_site=photo&search_source=search_form&version=llv1&anyorall=all&safesearch=1&use_local_boost=1&search_tracking_id=4JGoQvxhl0N9DGwJ2h-ETA&searchterm=pig%20farm&show_color_wheel=1&orient=&commercial_ok=&media_type=images&search_cat=&searchtermx=&photographer_name=&people_gender=&people_age=&people_ethnicity=&people_number=&color=&page=1&inline=122923786" target="_blank">FooToo</a>/Shutterstock

Let our journalists help you make sense of the noise: Subscribe to the Mother Jones Daily newsletter and get a recap of news that matters.


For decades, it’s been thought that low, regular doses of antibiotics help livestock grow big—thus increasing meat producers’ profits. So common is the practice of lacing farm animals’ feed with the drugs that an astonishing four-fifths of all antibiotics in the United States now go to livestock.

But a new meta-analysis by two Princeton researchers shows that antibiotics aren’t as effective at promoting growth as they used to be. Studies from 1950-1985 suggested that antibiotics increased weight of young pigs by an average of about 17 older pigs by 4 percent. But similar studies since 2000 found much less dramatic results: 1 percent increase for young pigs and no measurable increase for older pigs.

No one knows why the drugs have become less effective—and in fact, there’s no consensus on how exactly antibiotics increased growth in animals to begin with. One theory is that the drugs fight low-level infections, which allows the animal to use its energy for growing instead of warding off germs. The authors of the new analysis theorize that as hygiene at livestock operations improve, the rate of infections might be decreasing, thus negating the need for antibiotics.

Another (scarier) possibility: Bugs that cause common animal infections are becoming resistant to the antibiotics. The consequences of antibiotic resistance, of course, go far beyond pigs’ rates of growth. As my colleague Tom Philpott has reported, superbugs can jump from animals to humans. Antibiotic-resistant infections already kill 700,000 people every year worldwide. A recent UK report predicted that number will rise to 10 million by 2050.

“If the benefits of [antibiotics for animal growth] have diminished, then it becomes reasonable to be cautious and avoid the potential public health costs,” write the new report’s authors. “Antibiotics are not needed to promote growth, but they are essential to treat infectious diseases and maintain animal health.” 

THE TRUTH IS...

what drives Mother Jones' team of 50-plus journalists. The truth is powerful, as evidenced by how hard those with something to hide, or profit to gain, seek to discredit it. The truth, stated boldly and reported meticulously, is what draws so many readers to Mother Jones.

And the truth is, going into the final 4 days of the year we still needed to raise $TK to hit our $350,000 goal and start 2021 on track. It's nerve-wracking, wondering if the big spike we normally see at the end of December is going to be another thing that doesn't go as planned in 2020, or worse, if, now that Donald Trump is set to leave the White House (for longer than a taxpayer-funded golf trip to a property he owns), folks might be pulling back from fighting for the truth and a democracy and think the hard work is done.

It's not, and if you can right now, please consider a year-end donation to support our team's fearless nonprofit journalism so we can close that big fundraising gap and finish the year strong, ready for all that's ahead in 2021. Whether you can give $5 or $500, it all matters in keeping us charging hard, and we'd be grateful.

payment methods

THE TRUTH IS...

what drives Mother Jones' team of 50-plus journalists. The truth is powerful, as evidenced by how hard those with something to hide, or profit to gain, seek to discredit it. The truth, stated boldly and reported meticulously, is what draws so many readers to Mother Jones.

And the truth is, going into the final 4 days of the year we still needed to raise $TK to hit our $350,000 goal and start 2021 on track. It's nerve-wracking, wondering if the big spike we normally see at the end of December is going to be another thing that doesn't go as planned in 2020, or worse, if, now that Donald Trump is set to leave the White House (for longer than a taxpayer-funded golf trip to a property he owns), folks might be pulling back from fighting for the truth and a democracy and think the hard work is done.

It's not, and if you can right now, please consider a year-end donation to support our team's fearless nonprofit journalism so we can close that big fundraising gap and finish the year strong, ready for all that's ahead in 2021. Whether you can give $5 or $500, it all matters in keeping us charging hard, and we'd be grateful.

payment methods

We Recommend

Latest

Sign up for our free newsletter

Subscribe to the Mother Jones Daily to have our top stories delivered directly to your inbox.

Get our award-winning magazine

Save big on a full year of investigations, ideas, and insights.

Subscribe

Support our journalism

Help Mother Jones' reporters dig deep with a tax-deductible donation.

Donate