Technical Keynote Session 4

What Proportion of Genetic Variation Is Explained by DNA Tests?

By Troy Smith

In discussions of advancements in genetic prediction during the 2009 Beef Improvement Federation (BIF) symposium, Cornell University geneticist R.L. Quaas said evaluation of commercial DNA tests has begun to shift from whether a certain test works to how well it works.

“Increasingly, we want to know what proportion of additive genetic variation [for a particular trait] is accounted for by a DNA test,” Quaas said. “Is it some, most or very little?”

Quaas said the National Beef Cattle Evaluation Consortium statistical team has applied three different estimators of percentage of genetic variation explained. All estimators performed similarly, on average, and none were very precise for tests associated with traits with low heritability. However, Quaas said the team considers the squared genetic correlation between the observed trait and the molecular breeding value to be the best estimator.

“We consider the reporting of percentage of genetic variation accounted for by DNA test to be an integral part of the validation process, in the short term,” Quaas concluded. This estimation will be required to incorporate DNA testing into the national cattle evaluation (NCE) system and, thus, for the beef industry to utilize this technology much more effectively and extensively than it is currently being utilized.”

Editor’s Note:This summary was written under contract or by staff of Angus Productions Inc. (API). To request reprint rights contact Shauna Rose Hermel, editor, at 816-383-5270. PowerPoints are posted with permission of the presenter and may not be reproduced in whole or in part without the express permission of the presenter.

The 41st BIF Research Symposium and Annual Meeting was hosted by the California Beef Cattle Improvement Association and the California Cattlemen's Association. For more information, visit www.bifconference.com or www.calcattlemen.org/bif2009.html.