ImmuneDEX

Program offers selection for immune competence.

by Troy Smith, field editor

“If we focus on resistance to one disease, we may inadvertently reduce resistance to another. The broader approach should be a good strategy to combat a disease complex like BRD,” stated CSIRO researcher Brad Hine, noting how the BRD complex involves multiple pathogens.

Expected progeny difference values, selection indexes, individual performance data and scoring systems may provide beef cattle producers with a variety of “numbers” to aid genetic selection. They can compare animals on the basis of numbers associated with a host of heritable traits. What producers have not had before is information indicative of seedstock candidates’ relative healthfulness or resistance to disease.

Australian scientist Brad Hine calls it tempting to believe that selection for productivity also results in greater healthfulness. But that’s not necessarily true. According to Hine, who is a researcher at Commonwealth Scientific and Industrial Research Organisation (CSIRO), a narrow focus on selection for productivity alone may actually increase animal susceptibility to disease.

In a presentation offered by Beef Improvement Federation Symposium Online, hosted June 8-12, 2020, Hine emphasized the need to find genetic solutions to disease susceptibility, particularly since antimicrobial products used as treatments are under increased scrutiny. Along with co-presenter Angus Australia Special Projects Manager Christian Duff, Hine explained efforts to develop tools for selecting animals that are genetically more resistant to disease.

The Australians’ objective is to enable selection for broad-based resistance to disease, an adaptive immune response. It’s not about targeting resistance to specific diseases.

“If we focus on resistance to one disease, we may inadvertently reduce resistance to another. The broader approach should be a good strategy to combat a disease complex like BRD (bovine respiratory disease),” stated Hine, noting how the BRD complex involves multiple pathogens.

Christian Duff explained Angus Australia-CSIRO collaborative research using phenotypic and genotypic information from more than 3,000 steers and heifers, representing 165 sires, to identify animals having a balanced ability to mount a cell-mediated response and an antibody response to disease challenge. Pathogens differ in their susceptibility to one type of response or the other. Both types are moderately heritable. Animals with ability to mount both types of response, at the same time, are expected to exhibit broad-based disease resistance against a wide range of pathogens.

According to Duff, genomic breeding values (ImmuneDEX Values) have been generated as tools for selecting animals capable of simultaneously mounting cell-based and antibody responses.

“The ImmuneDEX values are estimates of the genetic difference between animals for overall immune competence,” summarized Duff, noting that collection continues in the effort to further validate this selection tool.

The goal,” added Hine, “is to use this tool within a selection index, not targeting the selection of high-immune-response animals, but to remove the low responders.”

To access the archived presentation slides and webinar session, click here. For more information about this year’s symposium, including additional award winners and coverage of meeting, visit the Awards and Newsroom pages of BIFconference.com. For more information about BIF, visit BeefImprovement.org.

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