The amount of antibiotics sold for use in food animals in the United States rose 1 percent in 2015, and has been rising since the government started counting, according to a report released by the Food and Drug Administration. In a worrisome finding, the FDA said the majority of the livestock drugs sold were “medically important” to human health and were bought over the counter rather than prescribed by a veterinarian.

That’s perplexing, because many companies that produce or buy meat — particularly in poultry — have been saying they are cutting back on routine antibiotic use. And it’s surprising given that producers are supposed to cut way back on antibiotics starting January 1, when new federal rules restricting farm-antibiotic use become effective.

In addition to the rise in 2015, sales of all antibiotics for use in animals produced for meat have ballooned 24 percent since the government began counting in 2009, according to the report — which is known as the “ADUFA report” for its enabling legislation, the Animal Drug User Fee Act of 2008.

At a time when the government, and scientific and public health bodies, are intensely concerned about drug-resistant infections arising from antibiotic overuse — in agriculture as well as in medicine — that’s not a positive trend.

“Despite the frequent claims from the livestock producers that they are doing a better job of using antibiotics, the sales figures belie that,” said Dr. David Wallinga, a senior health officer with the Natural Resources Defense Council. “Things just keep going up, and this is creating the superbug problems that we are facing now.”

According to the report, the total amount of antibiotics sold for use in U.S. meat animals in 2015 was 34.34 million pounds (15.57 million kilograms), up from 27.75 million pounds (12.58 million kilograms) when counting began.

The situation is actually worse than those gross numbers show. The FDA breaks down the antibiotics used in animals into “medically important” and “not currently medically important.” The designation describes whether use of the drugs might endanger human health, by causing drug-resistant infections to emerge, while undermining the effectiveness of the antibiotic that would be needed to cure that infection.

In 2015, 21.38 million pounds (9.7 million kilograms) of medically important antibiotics were sold for animal use, and 12.95 million pounds (5.87 million kilograms) that were not medically important. But only sales of the medically important antibiotics increased from the year before, by 2 percent (and 26 percent since 2009); sales of the not-important category actually decreased by 1 percent.

And that hike happened even though the number of meat animals raised in the United States actually declined slightly from 2014 to 2015, by 4.3 million animals, about 1.7 percent.

Another way the agency divides the numbers is by how the drugs are bought and how they are administered, and it’s in those categories that the scope of the farm-antibiotic problem is evident. In 2015, 97 percent of the medically important antibiotics — which are ones that are functionally identical to the antibiotics used in people — were sold over the counter, such as in a feed store, without a veterinarian’s involvement. And 71 percent were used for “production or therapeutic indications,” meaning they were not given to cure an illness, but to create weight gain, or to keep flocks or herds healthy in crowded conditions.

None of those uses — buying antibiotics without a prescription, giving them to prevent infections from occurring, giving them to produce effects that don’t have anything to do with illness — are legal in human medicine. And come January, some won’t be legal in animals either.

Rules that the FDA passed in 2013, and that come into effect at the end of this year, make antibiotic use for weight gain — what’s usually called “growth promotion” — effectively illegal. (Though the change is being made by a voluntary mechanism called a “guidance,” manufacturers are treating it as though it has legal force.) They also require any other antibiotic use to be supervised by a veterinarian, rather than leaving it up to a producer to decide.

The FDA released the numbers Thursday afternoon in a surprise holiday drop. Advocates who saw the numbers, who have been pressing for years for changes in farm antibiotic use, all sounded exasperated that nothing has changed. The ADUFA reports trail the calendar by a year, so the numbers show what producers were doing one year out from the rule change — but given just one year remaining, the advocates all questioned whether producers would be able to remove such large amounts of antibiotics that fast.

“The upward trend strongly suggests that the FDA’s voluntary guidelines, set to take effect the end of this year, will likely have little effect on reducing unnecessary antibiotic use on farms,” said Matt Wellington, the field director of US PIRG’s antibiotics program.

Maryn McKenna is a National Geographic contributor, and the author of Superbug and Beating Back the Devil. She last wrote for FERN about how the Netherlands cut antibiotic use on farms. Her new book on antibiotics in agriculture will be published by National Geographic Books/Penguin Random House in 2017. She writes regularly about antibiotics and agriculture for Ag Insider.