Consumers today have a lot of questions about antibiotic resistance and how it might be linked to livestock farming. But according to Michelle Sprague, a veterinarian with Audubon Manning Veterinary Clinic (AMVC) Management Services, there has been no evidence of a direct link between antibiotic use in livestock and resistance seen in human medicine.
“It’s not a link that’s quite as easily drawn as people make it out to be,” Sprague said. “Eating meat from an animal that’s been treated with an antibiotic does not infer antibiotic resistance in humans because the antibiotic is out of the animal’s system before it’s slaughtered, by law, with observance of withdrawal times.”
However, experts agree that those in the human medical community and the livestock industry need to work together to reduce antibiotic resistance by the overall reduction in antibiotic use.
When farmers work with veterinarians to determine the course of treatment, they determine the best treatment, route, and duration of use. This information follows the animal health manufacturer’s label instructions regarding use, and the veterinarian’s experience in the field.
Farmers and veterinarians not only follow the animal health manufacturer’s label, they must also follow the Food and Drug Administration’s (FDA) limits on residues. The FDA sets limits on how much residue can remain in the meat, which ensures not only veterinary oversight, but also food safety.
“Meat is basically antibiotic-free,” said Richard Raymond, former U.S. Department of Agriculture (USDA) Undersecretary for Food Safety.
There is a strict withdrawal period set by the FDA that determines how long before the animal goes to slaughter that the course of antibiotic should be finished. Before slaughter, the animal processes the antibiotic, which flushes the illness and the antibiotic out of its system before it’s even close to being slaughtered.
Chris Rademacher, a swine extension veterinarian at Iowa State University (ISU), noted that farmers often adhere to a longer withdrawal period than what’s required by the FDA. That’s because export partners like Japan require a longer withdrawal period to be eligible for exports.
“Because different countries have different tolerances, for export markets we usually go above and beyond with what the withdrawal period states on the label,” Rademacher said.
For example, anybody who sells exported pork may have a 28-30-day withdrawal period when the FDA only requires seven to 10 days in the United States.
“Some farmers don’t use the antibiotic in the last 30 to 60 days before market as a safeguard unless pigs really get sick,” Rademacher said.
After food animals are slaughtered, USDA inspectors at the packing plant test meat for drug residues before the meat enters the food chain. If meat is found to have an amount of drug residue that’s above the legal limit, the meat is destroyed, and consumers never see the product in the grocery store.
Technology has helped in detecting drug residues, said Peter Davies, a professor at the University of Minnesota’s College of Veterinary Medicine.
In 1978, more than 13 percent of hogs at meat processing plant tested positive for antibiotic residues higher than the limit set by the FDA. In 2012, the number had dropped to 0.14 percent.
“You’ve got to realize that with modern technology now, we are able to detect extremely low levels of (antibiotic) residues,” he said. “The residue-detection program says that there is no public health risk in 99.9 percent of the product.”
Raymond said the human health community needs to take a closer look at its use—and overuse—of antibiotics. This, he said, is a factor leading to antibiotic resistance.
“The CDC (U.S. Centers for Disease Control) has said 50 percent of all outpatient antibiotic prescriptions are unnecessary. That’s irresponsible,” he said. “A lot of common colds are being treated with antibiotics.”
But Raymond said those in the livestock industry and in human medicine should work together to reduce the amount of antibiotics that are used.
“The more antibiotics that are used—whether in human or animals—the more the bacteria are exposed to the antibiotic, and the more chance that bacteria will mutate to defend itself from that particular antibiotic,” Raymond said.
Antibiotic resistance is very real, Raymond said, and a reduction in the use of antibiotics will slow resistance.
“I think for anybody to deny there is an (antimicrobial resistance) issue, they are wrong,” Raymond said. “And for anybody to say we’re all going to die because of antibiotic use in animals, they are also wrong.”
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