EPD basics and must knows
Evaluating an animal’s pedigree may feel like an assignment in a statistics or accounting class. The numbers, pluses and minuses, abbreviations, and accuracy indications could make one’s head spin. But in the end, Expected Progeny Differences (EPDs) are simply another tool to help producers compare and select animals.
What are EPDs?
Expected Progeny Differences (EPDs) are genetic tools that can be used to try to predict the performance difference of the progeny of two different animals. “The numbers themselves actually don’t mean anything unless they are compared to other numbers,” Earl Ward, NE Area Livestock Specialist with Oklahoma State University Extension, said.
For instance, if a producer wants to look at the EPDs of two bulls, bull A and bull B, then the EPDs help a producer understand the differences between the two. If bull A has a birth weight (BW) EPD of +8.0, that number doesn’t give a producer a lot of information on its own.
However, it does allow producers to compare bull A to another. In this example, assume bull A is going to be compared to bull B which has a BW EPD of +2.0. This means that bull B’s progeny would be 6 pounds lighter (8 pounds – 2 pounds) at birth, than the offspring of bull A.
EPDs also allow producers to compare a bull to the breed average. Each breed has its own average EPDs. For example, if these were Angus bulls, the average BW EPD for the current sires is +1.2, which means that bull A’s offspring would be 6.8 pounds heavier at birth on average than the average of the breed.
Evaluate Accuracy
EPDs are calculated from the genetic data that has been collected on that bull and the data from his progeny. “Since we are dealing with data there will be some errors, but this is adjusted for by looking at the bull’s EPD accuracy,” Ward stated. “The accuracy of the EPD and the EPD itself will change over time when more data is sent in from that bull’s progeny.”
The accuracy EPD is on a scale from 0.0 to 1.0. The closer to 1.0, the more confidence producers can have in the EPD reported. “So, if I am looking for a bull to put on my small heifers and I need him to be a bull with low birth weights, then I definitely would not pick a bull that is so young that he has not had data reported,” Ward said. “I would pick a bull with an EPD within the range I am comfortable with and had a considerably high accuracy.”
Understanding the Numbers
The EPD numbers represent a variety of factors. Some EPDs are based on pounds such as birth weight (BW), weaning weight (WW), yearling weight (YW) and Milk. However, other EPDs are simply reference numbers like calving ease direct (CED) or docility (Doc).
Additionally, some EPD indexes are a combination of several performance factors. One example of this is dollar beef value ($B). Dollar beef value is the expected average of the progeny’s postweaning performance and carcass value.
It is important to keep in mind the numbers are for comparison. Some animals will be above or below the breed average. Producers should check with their breed to understand what the average is, because the breed average may not be 0.0.
For years, producers could only compare EPDs between animals in the same breed, but that is no longer the case. “A newer development is that now we have the ability to compare EPDs across breeds,” Ward shared. “Until this tool was established there was no way to compare bulls from two different breeds.”
Look at Variety of Traits
Which EPDs producers focus on, depends on what they want to accomplish. Livestock experts recommend understanding the breed averages and use the EPDs as a tool to compare animals. The traits that are most important to the producers, would be the areas they want to pay the most attention to.
Livestock extension experts encourage producers to study and do their homework when it comes to EPDs. Then producers will be best equipped to choose animals that fit the perimeters and goals for their operations.
For information about calculating EPDs, visit go.ozarksfn.com/irn
