Emerging Technologies

DNA Marker Panel Validation Update by the National Beef Cattle Evaluation Consortium

Presented by Alison L. Van Eenennaam, Department of Animal Science, University of California, Davis; R. Mark Thallman, U.S. Meat Animal Research Center, Clay Center, Neb.; Richard L. Quaas, Department of Animal Science, Cornell University, Ithaca, N.Y.; Kathy Hanford, Departments of Statistics and Animal Science, University of Nebraska, Lincoln, Neb.; and E. John Pollak, Department of Animal Science, Cornell University, Ithaca, N.Y.

Abstract:
The U.S. National Beef Cattle Evaluation Consortium (NBCEC) has been involved in the validation of commercial DNA tests for quantitative beef quality traits since their first appearance on the U.S. market in the early 2000s. Validation has been defined as finding a significant association between genetic tests and traits as claimed by the commercial genotyping company based on phenotypes and genotypes derived from reference cattle populations. The validation process and analyses have evolved as the DNA-testing industry has matured from single gene tests to panels involving an ever-increasing number of markers.

Results of validations performed over the past year are posted on the public NBCEC web site (www.nbcec.org) and will be presented. It is becoming clear that a validation process that is focused on simply confirming (or not) an association between DNA test results and the trait of interest does not provide producers with the type of information they need to make decisions on the value proposition of a particular test to their enterprise.

Given this concern, and the likelihood that validation requests will increase significantly as products derived from high-density SNP assays proceed toward commercialization, it seems an opportune time to refocus validation efforts on estimating the effect of DNA tests. The proportion of the genetic variation accounted for by a DNA test can be obtained as the square of the genetic correlation (rg) between the Molecular Breeding Value (MBV) and the Breeding Value. Obtaining the estimate of rg requires estimating the same (co)variance parameters as would be needed to integrate an MBV directly into the current genetic evaluation system for expected progeny differences. Integration of DNA test results into the national cattle evaluation system will likely enhance widespread adoption of this technology in the beef industry.

Editor’s Note: The above material is provided by and posted with permission of the Beef Improvement Federation. Please direct reprint requests to BIF via the “Contact BIF” page at www.beefimprovement.org.