MARC scientists believe DNA tests will allow
cattle breeders to increase the speed and accuracy of traditional assessment
methods. Photo: Angus cattle on pasture. Click the image for more
information about it.
Genetic Tests Beef Up Cattle Breeding
March 22, 2006
Geneticists with the Agricultural
Research Service (ARS) in Clay Center,
Neb., are improving traditional cattle breeding methods with marker-assisted
selection, a process that incorporates DNA tests into traditional genetic
Traditionally, breeders have used visual appraisal to estimate cows
genetic merit. By carefully recording the characteristics of herd members and
their descendents, animal breeders can calculate an animals Expected
Progeny Difference, or EPD. This is a figure estimating the average performance
of specific traits for an individuals offspring.
More recently, geneticists have developed DNA tests associated with
important traits in cattle. These tests might someday be incorporated into the
established selection process.
According to ARS geneticist
Mark Thallman, incorporating DNA tests in breeders calculations could
improve the accuracy of their EPDs and place the appropriate degree of emphasis
on the DNA tests.
F. Allan, he is testing that theory, using a herd selected for producing
twins as a prototypical population. Previous research located three genetic
regions linked to the twinning trait. This information has been incorporated
into the scientists calculations since 1998, enabling them to make more
accurate genetic predictions, or marker-adjusted EPDs.
The twinning experiment is simply one example of marker-assisted
selections potential. In similar work, researchers from
Cornell University, ARS and
Iowa State University incorporated DNA
test results into a genetic evaluation of Simmental cattle for tenderness,
allowing Simmental breeders to use marker-assisted selection for tenderness.
In the future the technique could be used to improve other desirable traits,
such as efficiency, fertility and growth rate.
Marker-assisted selection will allow breeders to increase the speed and
accuracy of traditional assessment methods, but its advantages extend beyond
the seedstock industry. Commercial cattle producers would be able to purchase
bulls with superior genetics. The desirable characteristics in the livestock
would ultimately translate into better products for consumers.
ARS is the U.S. Department of
Agricultures chief scientific research agency.