If you enjoy a good roasted chicken and would like to continue to do so, you might want to stop reading now.

Because chicken as we know it—breasts cut up onto a Caesar salad, nuggets fried in pieces in a bucket, drumsticks wrapped in plastic in the supermarket—is hardly the Little Red Hen of the children's tale, free to peck around the farmyard as she goes through the steps of baking her own bread. Chicken is now a commodity protein to be delivered in the form of white meat as cheaply as possible to consumers. And the cost of that system is considerable, as Maryn McKenna outlines in her book Big Chicken.

Ag vs. antibiotics

McKenna’s crusade is against the rising threat of antibiotic resistance, and it is a worthwhile endeavor. Her description of a post-antibiotic world looks a lot like the pre-antibiotic world, in which roughly a quarter of children died of infectious diseases before their fifth birthday, surgery and chemotherapy were impossible, and a skinned knee could be fatal—and often was. It was a horrifying time to be alive.

The development of antibiotic resistance is the inevitable flipside to antibiotic use; it's how evolution works. When people needlessly use antibiotics or use them improperly—which we still do—antibiotic resistance intensifies, evolving more quickly and granting pathogens immunity to a wider collection of drugs.

But as McKenna argues in Big Chicken, the real culprits that have brought us to the brink of a post-antibiotic age are not overzealous parents and doctors treating kids with ear infections. They are the large agricultural corporations that daily give inordinate amounts of antibiotics to the farm animals we eat.

Farm animals in the US, such as pigs, cows, and chickens, receive more than 80 percent of the antibiotics sold in the States. These animals do not get antibiotics to cure bacterial infections that they harbor, as people do. They get antibiotics because, in 1949, a researcher at Lederle Labs discovered that adding antibiotics to chicken feed made the birds gain weight faster. (Antibiotics have the same effect on people, btw.) By lacing animal feed with these drugs, farmers and ranchers could get their animals up to an ever-increasing slaughter weight more quickly and with the same amount of food.

Since the antibiotics also protect the animals from getting any infections in the first place, the farmers could now pack ‘em in tight and raise more of them in a smaller space. This daily dose of antibiotics created and enabled massive-scale animal husbandry as it is practiced today the world over.

It would be reassuring to think that the scientists, farmers, breeders, businessmen, politicians, and policymakers who allowed this to happen (McKenna names them all) didn’t know the ramifications of their actions, that they had benevolent intentions and were just trying to make good on President Herbert Hoover’s “chicken in every pot” campaign promise of 1928. But as McKenna tells it, they were motivated more or less by their bottom lines, not by human health and nutrition (and certainly not by animal health and welfare). They knew full well the risks they were running.

One of those risks was recognized almost as soon as antibiotics were discovered. Penicillin, the first antibiotic, was identified in 1928 and came on the market in 1940; in 1945, its discoverer, Alexander Fleming, said: “The thoughtless person playing with penicillin treatment is morally responsible for the death of the man who succumbs to infection with the penicillin-resistant organism.”

Big lobbying

Antibiotics for growth promotion and disease prevention were banned in the UK in 1971. The US FDA tried, starting in 1972, but the lobbyists stepped in. They came from everywhere—from the pharmaceutical companies who made and sold the drugs, to the American National Cattlemen’s Association who appreciated their effects.

Which may have been just as well since the UK plan kind of backfired; since it only banned antibiotics for growth promotion and disease prevention, the ban still allowed farmers to treat infections in their farm animals if they got a prescription from a vet. This is exactly what the farmers did, and it resulted in farm animals getting even more antibiotics than they did before the ban went into effect. The same thing happened when the EU tried a ban on growth-promoting drugs in 1999.

The scale of the problem had not been appreciated for some time because neither drug companies nor ag companies were required to disclose how much antibiotics, or even which antibiotics, they were feeding their animals. Ironically, that changed when animal drug companies got annoyed that it took so long for new drugs to get approved.

In 2003, drug companies pressed the FDA to speed things up, and Congress insisted that they give up some sales data if they wanted the expedited process. In 2009, the resulting federal report revealed that farm animals got about 30 million pounds of antibiotics that year, including every class of drug we have. That number has risen every year since.

Now, people don’t want antibiotics in their food, and market demand—ever the incentive—has spurred companies to change. In February 2014, Chick-fil-A announced that it would stop serving chicken that had been given antibiotics. Months later, Perdue said that it no longer gives antibiotics to its chickens; it relies on healthier diets, vaccinations, and more light and space to move in order to keep the chickens healthy.

As of January 2017, the FDA made giving antibiotics to farm animals for growth promoting purposes illegal, although farmers can still use them for disease prevention under a vet’s advice.

So even the companies that had not yet voluntarily done away with antibiotics will now have to fall in line. But the change is no great loss for them; the growth-promoting properties of antibiotics have gone as far as they could go. Thanks to other changes in diet and living conditions, the drugs simply don’t work anymore.