2018 Survey of factors associated with antimicrobial drug use and stewardship practices in adult cows on conventional California dairies: immediate post-Senate Bill 27 impact

Pius S Ekong; Essam M Abdelfattah; Emmanuel Okello; Deniece R Williams; Terry W Lehenbauer; Betsy M Karle; Joan D Rowe; Sharif S Aly

doi:10.7717/peerj.11596

2018 Survey of factors associated with antimicrobial drug use and stewardship practices in adult cows on conventional California dairies: immediate post-Senate Bill 27 impact

PeerJ. 2021 Jul 13:9:e11596. doi: 10.7717/peerj.11596. eCollection 2021.

Authors

Pius S Ekong^{1

2}, Essam M Abdelfattah^{1

3}, Emmanuel Okello^{1

4}, Deniece R Williams¹, Terry W Lehenbauer^{1

4}, Betsy M Karle⁵, Joan D Rowe⁴, Sharif S Aly^{1

4}

Affiliations

¹ Veterinary Medicine Teaching and Research Center, University of California, Davis, Tulare, CA, United States.
² Department of Epidemiology, National Veterinary Research Institute, Vom, Plateau, Nigeria.
³ Department of Animal Hygiene and Veterinary Management, Faculty of Veterinary Medicine, Benha University, Qalubiya Governorate, Egypt.
⁴ School of Veterinary Medicine, Department of Population Health and Reproduction, University of California, Davis, California, United States.
⁵ Cooperative Extension, Division of Agriculture and Natural Resources, University of California, Orland, California, United States.

Abstract

Background: Antimicrobial drugs (AMD) are critical for the treatment, control, and prevention of diseases in humans and food-animals. Good AMD stewardship practices and judicious use of AMD are beneficial to the preservation of animal and human health from antimicrobial resistance threat. This study reports on changes in AMD use and stewardship practices on California (CA) dairies, following the implementation of CA Senate Bill 27 (SB 27; codified as Food and Agricultural Code, FAC 14400-14408; here onward referred to as SB 27), by modeling the associations between management practices on CA conventional dairies and seven outcome variables relating to AMD use and stewardship practices following SB 27.

Methods: A survey questionnaire was mailed to 1,282 grade A licensed dairies in CA in spring of 2018. Responses from 132 conventional dairies from 16 counties were included for analyses. Multivariate logistic regression models were specified to explore the associations between survey factors and six outcome variables: producers' familiarity with the Food and Drug Administration's (FDA), Silver Spring, WA, USA medically important antimicrobial drugs (MIAD) term; change in over-the-counter (OTC) AMD use; initiation or increased use of alternatives to AMD; changes to prevent disease outbreaks; changes in AMD costs; and better animal health post SB 27. We employed machine learning classification models to determine which of the survey factors were the most important predictors of good-excellent AMD stewardship practices of CA conventional dairy producers.

Results: Having a valid veterinary-client-patient-relationship, involving a veterinarian in training employees on treatment protocols and decisions on AMDs used to treat sick cows, tracking milk and/or meat withdrawal intervals for treated cows, and participating in dairy quality assurance programs were positively associated with producers' familiarity with MIADs. Use or increased use of alternatives to AMDs since 2018 was associated with decreased use of AMDs that were previously available OTC prior to SB 27. Important variables associated with good-excellent AMD stewardship knowledge by CA conventional dairy producers included having written or computerized animal health protocols, keeping a drug inventory log, awareness that use of MIADs required a prescription following implementation of SB 27, involving a veterinarian in AMD treatment duration determination, and using selective dry cow treatment.

Conclusions: Our study identified management factors associated with reported AMD use and antimicrobial stewardship practices on conventional dairies in CA within a year from implementation of SB 27. Producers will benefit from extension outreach efforts that incorporate the findings of this survey by further highlighting the significance of these management practices and encouraging those that are associated with judicious AMD use and stewardship practices on CA conventional dairies.

Keywords: Antimicrobial drug use; Antimicrobial stewardship; California dairy industry; Decision tree; Gradient boosting; Judicious use of antibiotics; Logistic regression; Machine learning; Random forest; Risk factors.

Grants and funding

This research was funded by the California Department of Food and Agriculture (PI Sharif Aly), and the University of California Davis’s School of Veterinary Medicine and Office of Research’s Principal Investigator Bridge program (PI Sharif Aly). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.