A multidisciplinary research team is developing rapid genomic testing methods that will change the way broiler fields make decisions about antimicrobial use and ultimately improve antimicrobial stewardship.
Bovine respiratory disease (BRD), more commonly known among livestock producers as shipping fever, is the leading cause of illness and death in North American feedlots.
Although veterinarians and managers in the feedlot fields currently rely on clinical history and symptoms to diagnose or establish a level of risk for BRD, those clinical symptoms do not identify the specific pathogen (disease factor) that is causing the disease. Clinical signs also do not indicate whether the pathogen contains genes that make it resistant to antimicrobial treatments.
Current diagnostic tests that can answer these questions require up to a week of processing time, which means that veterinarians often prescribe antimicrobials without a specific diagnosis. There is pressure to provide diagnostic information for prescribing antimicrobials in order to demonstrate antimicrobial stewardship.
Simon Otto, MD, associate professor of public health at the University of Alberta and a graduate of Western College of Veterinary Medicine (WCVM).
Otto and Dr. A US dollar project aimed at providing timely diagnostic information for feedlot cattle to support antimicrobial stewardship.
By developing a rapid test technology that can identify respiratory pathogens and any antimicrobial resistance in calves entering feedlots, it aims to inform accurate antibiotic treatment at the group level.
After the calves are weaned from their mothers, they are sent to fattening pens where they are fed until they reach optimum slaughter condition. During transport and upon arrival at the feedlot, these calves mix with animals from other farms and farms – a practice that exposes them to new bacteria and viruses. Changes in environment and management settings also stress calves and can lead to a poor immune system response.
“To give a comparison, it’s similar to children in nursery school,” says Otto. “When you take them to nursery or school in the fall, you add the pressure of the new classroom and you mix them up with a bunch of other kids where they spread around respiratory bugs and get sick. In the feedlot, if we can test a handful of calves as they enter the feedlot and find out what bacteria or viruses are and resistance potential they have, we can use that to direct antimicrobial therapy when they get sick a week or two down the road.”
Otto stresses that rapid genomic testing is not able to immediately diagnose point-of-care animals that are sick at this time. However, the tests will be used to create key pen-level information that can guide future antimicrobial treatments for BRD infection. Veterinarians and managers in the feedlot fields can then review that data when selecting an appropriate antimicrobial drug.
“With Genomic Origins, our goal is to get to a place where we can tailor antimicrobial drug selection based on detection of resistance patterns so that we can reduce ineffective treatments and reduce the chance of resistance selection,” explains Otto.
The Genome Origins team is also focused on keeping their project practical and relevant. A large part of Otto’s role involves industry engagement and working with researchers at U of A to analyze the economic impacts of an informed production system through diagnostic testing.
“We actually want to engage with the broiler industry and the broiler vets to understand and make sure that the system we design will be feasible and usable for them,” Otto says.
Besides improving antimicrobial stewardship in the beef industry, rapid diagnostic tests may be key to gaining access to international markets and maintaining antibiotics as a valuable tool for livestock.
“The international landscape of antimicrobial stewardship is changing for animal agriculture,” says Otto. “Potential legislative changes in the European Union may require diagnostic tests to justify the use of some antimicrobials. In other words, if we do not have a diagnostic test to support their use, we may not have access to some antimicrobial drugs for livestock.”
If diagnostic testing becomes a regulatory requirement for antimicrobial administration, the work of livestock genomic assets will be critical to navigating changing industry practices.
“We see rapid genomic methods and bioinformatics integration as platforms that can be applied to other diseases in the bovine and other livestock industries,” Otto says. “We see this as a platform that can be deployed for diseases in other industries.”