Antibiotic use in livestock has been in the news a lot lately, especially when used in the feed for food producing animals. A major component of regulatory decisions and ongoing debates has been the various estimates of quantities of antibiotics used in food animals.
Mike Apley, a clinical pharmacologist and professor of clinical sciences at Kansas State University, has investigated these uses for swine as part of a team authoring the paper “Use Estimates of In-Feed Antimicrobials in Swine Production in the United States." The paper was recently published in the journal Foodborne Pathogens and Disease.
“The team that developed this estimate has a broad range of training and experience, which allowed us to accurately represent antibiotic use practices in U.S. swine production," said Apley, the lead author on the paper.
The estimate was primarily based on U.SDA data from the National Animal Health Monitoring System, or NAHMS, Swine 2006 study, but the team added some new twists.
"The model for the final calculations had been used before," Apley said. “However, in our estimate, we started at farm-level survey data of producers from the USDA study and then used an additional veterinary practitioner survey to more precisely define in-feed antibiotic periods of use and dosing regimens for 102 different combinations of antibiotics, production phases and reasons for use.”
The authors of the paper asked three companies that sell a swine-only, in-feed antibiotic to evaluate the estimates and assess how accurately actual sales were represented. Two responses indicated the team was very close, and one response indicated the estimate varied from actual sales by approximately 50 percent.
“We felt that an external validation was necessary and were pleased to find that the team’s efforts had resulted in reasonable estimates," Apley said.
The paper classifies the results by both use category — growth promotion, disease prevention and disease therapy — and by the importance to human medicine as defined by the Food and Drug Administration. The team grouped the results in this manner to better inform the discussion on food animal antibiotic use.
“Gross tonnage estimates of overall use serve us little other than as sound bites,” Apley said. “While our estimates of use must still be used with great care, we can now at least start to properly frame discussions based on specific antibiotics and bacteria of interest."