Even though the use of antibiotics in livestock feed has been linked to an increase in drug-resistant bacteria, the U.S. Food and Drug Administration recently backed away from a 30-year-old proposal that would ban the use of antibiotics tetracycline and penicillin in livestock feed.
All the same, health advocacy groups are campaigning to eliminate the practice - and they're taking their message directly to farmers.
Kathleen Masterson, Harvest Public Media
Gail Hanson, a veterinarian with the Pew Research Center, says the feed Jeremy Gustafson feeds to his hogs contains antibiotics.
Questions about the use of antibiotics in livestock feed have been debated for decades. In its latest report (PDF), the FDA's Center for Veterinary Medicine outlined some of the important research that has contributed to our understanding of the issues.
Jeremy Gustafson, a hog farmer in outside Boone, Iowa, agreed to talk with the advocates from the Pew Research Center's Human Health and Industrial Farming Campaign and give them a tour of his farm. They brought along their shining example, a Danish farmer they flew in to talk about his experience transitioning his large-scale hog operation. Denmark banned the use of antibiotics in healthy hogs in 1998.
The first thing Danish farmer Kaj Munck noticed when he stepped inside is that Gustafson's piglets were tiny - about one-third the size of the pigs he starts out with.
"Normally in Denmark we are not weaning before 6.5, 7 kilos [about 14 or 15 pounds], because you have less problems," Munck said. "They're not missing the mother, they just (start) eating immediately, so that's a big, big difference. I'm not used to (seeing) small pigs like this."
Any hog farmer will tell you that getting pigs through the first few weeks of their lives after being separated from their mother and transitioned to a new pen with other pigs is a critical time. In Denmark, they take longer to wean the pigs, so they're stronger by the time they get to farmers. In the U.S., the hog industry instead leans heavily on using low-level antibiotics at that stage in their life.
Munck asked Gustafson if he'd prefer to receive older pigs.
"It would be great, in this situation," Gustafson said. But "we're just a contract grower so we follow their protocol."
The majority of hog farmers in the U.S. raise hogs through a contract, which means a livestock company or packing house owns the pigs. The company provides food, water and veterinary care and the farmer raises them in his barn for a set fee.
Gustafson likes the system because it gives him a guaranteed income, but he doesn't know much about what's in the feed he's required to use. Gail Hanson, a veterinarian with the Pew Research Center, said there's more than might initially meet the eye.
"There's an antibiotic in this creep feed that's given to the baby pigs," Hanson said. "That's just in the feed for all the pigs. In Denmark they don't do this at all."
It's this low-level use that's the real concern. The Food and Drug Administration has expressed particular concern over the use of tetracycline and penicillin, because these drugs are also used to treat humans. Using small doses of the medicine in livestock feed can breed bacteria that are resistant to antibiotics. Studies have found these bacteria in farms and on meat.
While cooking the meat properly will kill that specific bacteria, Hanson says that won't stop the bigger problem of growing drug-resistance.
"There's cross-contamination, that contamination that gets into the environment," Hanson said. "It's not just the bacteria that are making you sick, but it's all bacteria around us and they're sharing all of that knowledge of resistance, if you will."
What she means by "sharing knowledge" is really sharing DNA. Bacteria mix and multiply all the time, so when one develops a drug-resistance, it can easily be shared with other kinds of bacteria, including bacteria that affect humans.
In 2003, an expert global panel looked into the issue and concluded that human health is endangered by the use of antibiotics in livestock.
The livestock industry says it has reduced its use of antibiotics over the years.
"If you talk to the old-time veterinarians, they would say we use less antibiotics now than they did when we had all the animals on one site, when you were mixing source of pigs," said Liz Wagstrom, the chief veterinarian for the National Pork Producers Council.
There's no real way of determining if livestock antibiotic use has gone up or down, for years, the government didn't keep track. In 2009, the FDA started tracking the overall sales of different antibiotics for livestock feed, but doesn't follow how the medicine is used, in what dose or on which animals. And many feed formulas are proprietary, so much of that information is confidential.
Still, Hanson says you can do some rough math knowing that 29 million pounds of antibiotics were sold for livestock use each year in 2009 and 2010.
"It's a very broad-brush stroke, but if you look at that as milligrams of antibiotic per kilogram or per pound of meat produced, we're about six times higher than they are in Denmark," Hanson said.
With the FDA's decision not to enforce the ban on specific treatments, the regulatory outlook is murky at best.
For now, it's up to the industry to decide what judicious use of antibiotics looks like - and that use is neither regulated nor tracked by the government.