Source: Merial press release
Since the late 1970s, expected progeny differences (EPDs) have changed the way beef producers make selection and mating decisions. Matt Spangler, assistant professor and beef genetics extension specialist, University of Nebraska-Lincoln, says the introduction of EPDs empowered producers to make better decisions, leading to faster genetic progress.
"EPDs allow commercial and seedstock producers to focus on the genetic component of sire selection, which is the most important,” he says. "The use of EPDs has resulted in tremendous genetic change — particularly regarding growth and carcass traits.”
EPDs are a combination of information from various sources such as individual performance, pedigree and progeny data. Each EPD comes with an associated accuracy, which helps measure the reliability of the EPD. Dr. Spangler says though EPDs are an important factor to consider when evaluating young animals, producers should remember that these accuracies are typically very low on young animals.
"The accuracies associated with EPDs increase as more information becomes available,” he says. "The first EPD calculations for a young animal are an estimate based on its parents' pedigree index values and possibly some of its own performance data. For this reason, the accuracies are low until an animal has recorded progeny data, which may never happen in a commercial setting.”
Low-accuracy EPDs present a challenge for producers evaluating young seedstock. Dr. Spangler says, traditionally, there is essentially no difference in the accuracies of young sires, which means two bulls could have different EPDs, but due to the low accuracies, the difference may not be significant.
"For example, if one bull has a weaning weight EPD of 44 and another has a weaning weight EPD of 48, but both have an accuracy of 0.30, we cannot say that one of these bulls is any different than the other,” he says.
In addition to helping assess the true difference between animals, higher-accuracy EPDs mean the window of possible change for the respective traits decrease. The example below outlines this possible change and true EPD range for sires with two different accuracies for the same EPD value. This example uses an Angus breed-average EPD of +0.12 for ribeye area.