Multi-trait selection in a single-gene world


David Notter, Virginia Tech animal scientist, explains different genetic markers and their possible effects on breeders and their selection strategies.
As researchers sequence the bovine genome and develop genetic markers, cattle breeders will be able to use the genetic data to select for animal performance. However, the details of how to do that are yet to be determined, David Notter, Virginia Tech animal scientist, told participants at the 2004 Beef Improvement Federation (BIF) conference in Sioux Falls, S.D.

Genetic markers have the potential to improve the effectiveness of the National Cattle Evaluation (NCE), Notter said. They are continually being discovered, and new information on genetic markers is quickly developing. This field of study will get a big boost with the completion of the bovine genome map, which is expected within a year. In time, expected progeny differences (EPDs) will be calculated using not only performance data, but DNA information as well, he said.

“For most traits, genetic markers alone, as we have them today, are not going to account for enough genetic variation of the traits of interest to allow us to use genetic markers as the only selection trait,” Notter noted. “Instead, we’re going to have to have methods developed to combine information from genetic markers with information from performance reporting and simply use them as a way to improve and certainly not replace expected progeny differences.”

With the new data, he said, come new opportunities as well as complexities.

According to Notter’s proceeding paper (click here), selective genotyping and reporting of marker information is one of the most significant challenges to effectively using gene markers in NCE. But, he maintains, breeders and breed associations can apply the following suggestions to utilize DNA data:

• identify an array of genes and markers of importance to the breed (since different genes will be important to different breeds);

• develop a DNA collection strategy;

• develop a genotyping strategy;

• develop validation strategies (be prepared to validate markers to understand their total effect since some markers having effects on traits like marbling or leanness may have effects on other genes, like fertility); and

• incorporate marker information into NCE.

“We have an opportunity to see a new, significant increase in the accuracy of the way we do business,” he said. “It’s going to be exciting. It’s going to be frustrating. There’s going to be winners and losers. There’s going to be mistakes made, and at the end of the day, I have absolute confidence that [breeders] are going to be in a better position 10-15 years from now than they are today. What track that will take, I don’t know; but, it’s going to be very fun to watch.”

– by Crystal Albers