An EPD is a prediction of how future progeny of a sire or dam are expected to perform in a particular trait relative to other animals in the analysis. The key word is "difference" as the EPD itself does not imply "good" or "bad" performance. But rather, the EPD gives a prediction of the average difference to expect in the performance of an animal's progeny relative to other animals in the same analysis.
Expected Progeny Differences additionally and just as importantly are accompanied with an accuracy (ACC) value. Accuracy is a measure of reliability regarding the EPD evaluation for a performance trait. Accuracy is reported as a decimal number between zero and one. Large ACC values indicate greater accuracy and more certainty that the EPD will show little change as additional progeny information is obtained.
Expected progeny differences have been shown in numerous field studies to be the best information available to make a directional change in the cowherd for the trait of interest. Furthermore, researchers continue to search for ways to improve the accuracy of those predictions. To this end the AICA Breed Improvement Committee and Board of Directors during their spring meetings took a progressive approach to building a database of 50K genotypes. This will allow AICA to begin the process of enhancing our genetic evaluations through improved accuracy, especially in younger animals.
As AICA works through this process we must remember that we can only progress at the rate we collect phenotypes for those traits of value to the Charolais breed. Genomic enhanced evaluations rely on high quality phenotypic data (performance traits such as birth weights, weaning weights, ultrasound measurements, etc) to be included in national cattle evaluation programs.
Watch for details in the Charolais Journal and the AICA website over the summer as the details of this program are finalized and released.
Robert Williams is the director of breed improvement for the AICA. For further information: firstname.lastname@example.org
-- From the American-International Charolais Association newsletter
The American-International Charolais Association will begin developing 50K genotypes to improve accuracy of genetic evaluations. Photo by Progressive Cattleman staff.