Antimicrobial use quantification in adult dairy cows – Part 3 – Use measured by standardized regimens and grams on 29 dairies in the United States

Nora Schrag, Sandra M Godden, Michael D. Apley, Randall Singer, Brian Lubbers

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


This study describes antimicrobial use in terms of standardized regimens per cow year (REG/CY) and grams per cow year (GMS/CY) for 29 dairies in the United States during the years 2016 and 2017. To explore potential priorities for antimicrobial stewardship programs, these measures were stratified by both disease syndrome and antimicrobial class. Potential confounders of use measurements are discussed and challenges for measure interpretation are identified. When measured as REG/CY, the results indicate that mastitis is the disease syndrome with the greatest contribution to overall antimicrobial use. However, when GMS/CY is measured, metritis, lameness and unknown disease syndromes are also significant contributors. When use is stratified by antimicrobial class, measures of REG/CY indicate the greatest magnitude of use is the cephalosporin class. However, when measures of GMS/CY are stratified by drug class, use within the penicillin class contributes more than any other single class. These differences highlight the need for a more complete understanding of the relationship between antimicrobial use measures and their relationship to antimicrobial resistance selection pressure.

Original languageEnglish (US)
Pages (from-to)82-93
Number of pages12
JournalZoonoses and Public Health
Issue numberS1
StatePublished - Nov 17 2020

Bibliographical note

Funding Information:
Thank you to the producers who volunteered their time, data and expertise in helping to identify relationships between antimicrobial use measures and their potential confounders. Collaboration on data management and analysis were provided by the Center for Epidemiology and Animal Health (CEAH) at USDA:APHIS:VS in Fort Collins, Colorado. Funding for this project was made possible, in part, by the U.S. Food and Drug Administration through grant number U01FD005868. Views expressed do not necessarily reflect the official policies of the Department of Health and Human Services; nor does any mention of trade names, commercial practices, or organization imply endorsement by the United States Government. Special thanks to Dr. Kathe Bjork (USDA‐APHIS CEAH) and Dr. Susan Bright and Anna Nevius (FDA) for collaborations on data management and review of the manuscript.

Publisher Copyright:
© 2020 Wiley-VCH GmbH


  • antibacterial agents
  • days of therapy
  • defined daily dose
  • drug utilization
  • pharmacoepidemiology
  • resistance

PubMed: MeSH publication types

  • Research Support, U.S. Gov't, P.H.S.
  • Journal Article


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