The amount of antibiotics sold for use in livestock in the United States has dropped for the first time since data collection began, according to Food and Drug Administration numbers.
While that’s good news, the data also show for the first time which types of meat animals are receiving the most antibiotics. That turns out to be beef cattle and pigs, the species that are most challenging to raise, and thus will be hardest to wean off the drugs.
The data cover the last year before new federal rules went into effect this past January, restricting the use of some livestock antibiotics. So the drop they record wasn’t due to changes in policy; it is likely the result of consumer and government pressure to reduce the amounts of antibiotics given to farm animals. It’s notable that in the new numbers, chickens consume only a tiny portion of the antibiotics sold for livestock use, even though they are by far the most numerous meat animals in the United States. This may reflect the poultry industry’s campaign over the past three years to wean its birds off drugs.
The numbers come from the FDA’s 2016 Summary Report on Antimicrobials Sold or Distributed for Use in Food-Producing Animals, a document known as the “ADUFA Report” for the acronym of its enabling legislation. The first ADUFA Report was published in 2009.
“Seeing a reduction after seven years of increases is a good thing,” according to Laura Rogers, deputy director of the Antibiotic Resistance Action Center at George Washington University (GWU). “But we are still nearly at 9 percent more than in 2009, so we still have a lot of work to do. We need big reductions in use, and we need them quickly given the crisis we face from antibiotic resistance.”
Antibiotic use in livestock is dangerous because it encourages the development of antibiotic-resistant bacteria that can spread from farms via meat and through the environment, contributing to drug-resistant infections in humans. More than 23,000 people in the United States die each year from resistant infections; worldwide that number is an estimated 700,000 people. These are such high numbers that, in November, the World Health Organization called on countries to universally ban the use of antibiotics in livestock unless the animals are sick.
To parse that threat, the FDA’s report focuses on the subset of farm antibiotics that are “medically important” — that is, used in human medicine as well as in animals. While all farm antibiotic sales decreased by 10 percent between 2015 and 2016, sales of medically important antibiotics declined by 14 percent. Sales of tetracyclines, the most commonly used farm drug, went down by 15 percent; sales of penicillin by 10 percent; and sales of cephalosporins, a drug family that includes the popular human antibiotic Keflex, by 4 percent.
“We’ll need much steeper reductions in coming years if we’re going to keep antibiotics working to heal sick people,” Matthew Wellington, antibiotics program director for the nonprofit USPIRG, said in an emailed statement.
Because this report is the first to break out drug use by species, it provides the first insight into which animals account for the most antibiotic use, and also which antibiotics are most used on different types of farms.
Overall, cattle account for 43 percent of all medically important antibiotics sold for farm use, pigs account for 37 percent, turkeys account for 9 percent, and chickens for just 6 percent. (An additional 4 percent of drug sales were not assigned to any species.)
Animal-to-animal comparisons of drug use are imprecise, since species vary in size and have different lifespans. But an analysis done by the GWU center and Consumer Reports, using the newly released numbers along with USDA estimates of meat production in 2016, allows for comparisons across species. Their calculations show that, for every kilogram of meat produced per year, cattle receive 308.5 milligrams of antibiotics; hogs get 270.3 milligrams; and turkeys receive 218.8 milligrams. Chickens, by contrast, get only 19.75 milligrams per kilogram of the meat they yield, demonstrating how far ahead of the other meat species poultry production has moved.
Different animals also receive different types of drugs. Cattle account for 80 percent of the cephalosporins and 64 percent of the sulfa drugs sold, according to the FDA, while hogs receive 83 percent of the lincosamides (a family that includes the human drug clindamycin). Turkeys account for 63 percent of the sales of penicillin.
Those numbers may provide a clue for the important task of reducing antibiotic use as much as possible to keep the development of resistance under control.
“It’s exciting that the overall sales have diminished, but the numbers up to now have been difficult to interpret,” Karin Hoelzer, a veterinarian at the Pew Charitable Trusts, said by phone. “This can help us understand use patterns, and that will pinpoint the research needs for alternatives to antibiotics, which is what we need to help companies establish responsible use.”
Note: Updates figures in original story, reflecting a new analysis by GWU and Consumers Union on the amount of antibiotics per kilogram of meat produced per year.
Maryn McKenna is the author of Big Chicken: The Incredible Story of How Antibiotics Created Modern Agriculture and Changed the Way the World Eats. She writes regularly about antibiotics and agriculture for Ag Insider.