A Review of Alternative Practices to Antimicrobial Use for Disease Control in the Commercial Feedlot – Executive Summary

Abstract

The purpose of the present review was two fold: to give an overview of the modern feedlot industry in North America to provide context, and to search the scientific literature to identify alternative practices for antimicrobial use for disease control in that same industry. A fundamental assumption of the review was that reducing antimicrobial use would reduce the potential for antimicrobial-resistant bacteria to emerge and persist in the feedlot setting. To most effectively reduce antimicrobial use in the feedlot, one needs to find alternatives to prevent or effectively manage bacterial pneumonia in calves (often the principle reason for antimicrobial use) around the time of their arrival at the feedlot, as well as other bacterial diseases (eg, liver abscesses). Therefore, our key review question was the following: Are there management practices that do not involve the administration of antimicrobials that reduce the incidence of illness and mortality due to pneumonia, especially in high-risk feedlot calves? To answer this question, we set out to document the known risk factors for the emergence and maintenance of antimicrobial resistance (AMR) on feedlots, and the critical control points for these risk factors. We sought evidence for the effectiveness, efficiency and/or acceptability of various infection control points in a feedlot setting. We questioned whether the metaphylactic use of antimicrobials would affect the emergence of resistant bacteria in a feedlot setting, and asked what impact, if any, different drug use implementation strategies (including rotation of drugs used within a feedlot) might have on AMR. We also searched for management practices that reduce the incidence of liver abscesses in feedlot cattle, but that do not rely on in-feed or subtherapeutic antimicrobial use.