Antimicrobial use in wean to market pigs in the United States

Today, we are sharing a publication from Drs. Davies and Singer regarding antimicrobial use in wean-to-market pigs in the United States based on self-reported data from swine producers and veterinarians. This work is published in Zoonoses and Public Health in open access.


  • Demonstrates the feasibility of obtaining data on antimicrobial use in the United States swine industry through sharing of proprietary records within industry.
  • Provides the first substantial description of antimicrobial use in United States swine beyond annual sales and distribution data.
  • Indicates that specific metrics of antibiotic use that focus on conditions within individual industries will be most useful to advance stewardship.

Nine systems representing 20 million market pigs voluntarily reported their antimicrobial usage in years 2016 and 2017.

Most of the antimicrobials were used in the feed or water with chlortetracycline representing the highest tonnage of antimicrobial used across systems (~45%). The six most used antimicrobials (chlortetracycline, oxytetracycline, lincomycin, penicillin, bacitracin, tiamulin) accounted for 85% of total weight.

Only 2% of antimicrobials were used as injectables. Use of critically and highly important antimicrobials varied between participating systems and between the two years reported. Indeed, ceftiofur use remained stable except for a few system that decreased their in half between 2016 and 2017. Enrofloxacin use was stable except for one system that increased its consumption in 2017 compared to 2016.

Lastly, surveyed veterinarians reported that most of antimicrobial usage was happening in the early-stage nursery so that 60% of use happened in nursery and 40% in finishing overall.

Read the open-access publication for more detail on the active ingredients reported and the units used.


Data on antimicrobial use were collected for the 2016 and 2017 calendar years from swine producers in the United States. Nine large systems, collectively producing over 20 million market pigs annually, voluntarily provided data to advance understanding of antimicrobial use in the industry and to support antimicrobial stewardship initiatives. The scope of the study was limited to growing pigs, and the granularity of data varied across the systems. Data were summarized both qualitatively and quantitatively by antimicrobial class, active ingredient and route of administration (injection, water and feed). Data on the purpose of administration, doses and durations of administration were not available, but some information was provided by the responsible veterinarians. Aggregate data were similar both qualitatively and quantitatively in 2016 and 2017, although marked changes between years were evident within systems for some antimicrobials. Antimicrobial use (by weight) was dominated by the tetracycline class (approximately 60% of total use). Antimicrobials in classes categorized as critically important constituted 4.5% and 5.3% of total use in 2016 and 2017, respectively. In both years, fluoroquinolone (0.23%, 0.46%) and 3rd generation cephalosporin (0.15%, 0.11%) use collectively accounted for <1% of total use. Administration was predominantly oral in feed and water, and injection comprised approximately 2% of use overall, but around 12% for critically important antimicrobials. There was considerable variability among systems in patterns of antimicrobial use. This pilot project demonstrates the feasibility of acquiring antimicrobial use data via voluntary sharing. It is currently being expanded among larger swine production systems, and further efforts to enable confidential data sharing and benchmarking for smaller producers are being pursued by the swine industry. Recognized biases in the data caution against over‐interpretation of these data as an index of national use.

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