Tracking antibiotic use in food animals such as pigs in the United States is complicated by the fact that no one agency tracks the data. Photo courtesy of: JackF via Getty Images
While the FDA developed the Veterinary Feed Directive in 2015¹ to curb the use of antibiotics as “growth promoters,” nevertheless, tracking the sanctioned use of antibiotics in food animals in the U.S. has been problematic. A paper published in the U.S., entitled, “Antimicrobial use in wean to market pigs in the United States assessed via voluntary sharing of proprietary data,” (Peter Davies and Randall Singer), described the issues involved with attempting to come up with an intensity figure of mg/kg in just the pork industry.²
According to a Michigan State University paper, since the implementation of FDA’s Veterinary Feed Directive in January 2017, overall sales of medically important antibiotics approved for use in livestock has actually declined by 43% from a peak in 2015.³
FE spoke with Derek Armstrong, lead veterinary science expert for UK’s AHDB, to understand the issues with metrics in determining antibiotic use in livestock. “One of the problems is that it’s quite difficult to compare antibiotic use between countries because people don’t necessarily use the same metrics,” Referring to the paper published by Peter Davies and Randall Singer, Armstrong says the authors don’t even put a figure on the amount antibiotics used in total in the U.S. Instead, they give a figure for each type of antibiotics used in mg/kg of carcass weight.
“When you talk about mg/kg, it depends on how many kg of pig you use as your denominator. So in their study, Davies and Singer looked at using the market weight of the pig as the total weight of pigs [in the U.S.], whereas in Europe, we use the population correction unit (PCU). So a market weight of pigs would probably be around just under 100 kg, but in Europe they look at the pig as weighing an average of 65 kg over its lifetime. So it’s not easy to compare mg/kg when its mg/kg of a 90 kg pig vs. mg/kg of a 65 kg pig,” Armstrong adds.
A Michigan State University paper shows overall sales of medically important antibiotics approved for use in livestock have declined by 43% since 2015.
When asked what level of antibiotics the UK Food Standards Agency (FSA) allows in pork at the grocery store, Armstrong replied, “Zero. All antibiotics have a withdrawal period. So that’s the time when the pig’s body would process it and eliminate it from the body. You’re not allowed to sell the animal if it’s been treated, and it’s still within that withdrawal period. I guess it would be the same situation in the USA.”
The USDA, indeed, does have a monitoring program, and it is illegal to sell any meats containing an antimicrobial or any chemical above a maximum residual level (MRL). Imported meats must meet the same criteria as domestic meats in the U.S.⁵
“But essentially, there is a monitoring program as well; [FSA] will take samples at random and test those for antibiotics,” says Armstrong. “I think in general, 99% of samples will pass that test. And even some of the ones that fail will still be below the maximum residue limit, but [FSA] will investigate those as well. So essentially—whether it’s milk or meat—there should be no antibiotics in the food that we eat.”
There are two reasons to keep antibiotics out of food, says Armstrong. First is making sure there aren’t any residues left in the food we eat, and second, to minimize antibiotic resistance. “With our residue testing program, and not sending animals to slaughter until they completed their withdrawal period, the first should be a relatively small problem,” he says. And keeping unnecessary antimicrobials out of the environment in general means that bacteria will develop resistance more slowly, making antimicrobials more effective when actually needed.
References:
1 “Veterinary Feed Directive (VFD): Final Rule,” 2015, 2019; FDA Web Site
2 “Antimicrobial use in wean to market pigs in the United States assessed via voluntary sharing of proprietary data;” Peter R. Davies and Randall S. Singer; 17 November 2020; Zoonoses and Public Health, Vol. 67, Issue S1, https://doi.org/10.1111/zph.12760.
3 “Antibiotic use in swine production,” Casey Zangaro, Michigan State University Extension - May 15, 2019
4 “Antibiotic Consumption In U.S. Pork, Beef, And Turkey Industries Vastly Outstrips Comparable Industries In Europe, And The U.S. Chicken Industry,” Natural Resources Defense Council (NRDC), Nov. 2018
5 “The Truth About: Meat and Antibiotics,” Minnesota Antibiotic Stewardship Collaborative, 8/19/2019.