Back to the Basics with Bauer: What are EPDs?

By Lance Bauer

Expected Progeny Differences (EPDs) are a tool that can be used to compare an animal to another animal or the average of the breed.  The numbers can tell you how the progeny of one animal is expected to perform when compared to others for that same trait. There is an accuracy associated with the EPD that will improve with more information for a certain animal. The value of the EPD can change as well with more information on an animal’s progeny. EPDs are calculated using the estimated relatedness of animals based on pedigree, the performance of the individual, the performance of related individuals and other factors that could influence the trait that is being calculated. These other factors are put into the equation in order to be factored out and create a more even playing field for all animals. Once an animal has offspring the performance of the offspring is included in the calculation of the EPD. The use of EPDs can be used by seedstock breeders, as well as commercial producers to improve the performance of their herd. It can be difficult at first to know how to properly utilize the information that EPDs present, but that task can be made simpler by the using indices that combine and weight EPDs to come up with a single value that can help in the selection of animals for a specific part of production. The calculation of EPDs is a process that is changing with new genomic technologies.