by New Mexico State University Extension Livestock Specialist Marcy Ward, PhD.
Formula-based genetic evaluation of beef animals has been around since the early 1960s. Overtime, a combination of statistical equations, actual performance data, and pedigree information have been used to develop what came to be known as expected progeny difference (EPD) values. These values represent how well an individual’s offspring may perform within a trait across a breed average of that trait. The purpose of EPDs is to provide producers a tool to compare the potential performance between breeding animals. The goal is to allow producers to select superior bulls or heifers to improve the genetic performance of their herd.
The beef industry as a whole did not start to fully use EPDs as a selection tool until the mid to late 1980s. Once the use of EPDs became more widely accepted, the rate of performance efficiency in beef cattle improved dramatically. As an example, the Tucumacari Bull Test located in Tucumcari, New Mexico, has been performance testing bulls since 1962. In that first year of the test, bulls averaged 2.5 pounds of gain per day and required 10.2 pounds of feed to achieve one pound of gain. In the 2017 test, bulls averaged 3.87 pounds of gain per day with a conversion rate of 6.05 pounds of feed per pound of gain. That is a 55 percent increase in rate of gain on 41 percent less feed.
So the question remains, what can producers expect in improved performance of their own herds by using EPD information? First, set goals before purchasing bulls. Identify areas that need improvement. More weaning weight? Focus on production EPDs (WW, YW, TM, MWW). Fewer calving problems? Focus on maternal EPDs (BW, CED, CEM). Retain ownership or direct marketing? Focus on carcass and performance EPDs (YW, REA, IMF, FAT). From there, a producer can look at a category of EPDs to narrow down the number of bulls to choose from based on their ranking in those EPDs within their contemporary group.
For example, there are certain criteria one might use to improve weaning weights in their herd. There are four EPDs that offer the most potential of improving weaning weights in calves. In the Brangus breed, weaning weight (WW), yearling weight (YW), total maternal (TM), and milk (MWW) EPDs may influence actual weaning weights. Brangus bulls that offer genetic potential to improve weaning weights will carry EPDs greater than 25.4, 49, 21.6, and 8.9 for WW, YW, TM, and MWW respectively, according to IBBA Black Brangus Cattle Evaluation, September 2017.
There are a few things to consider when evaluating the genetic potential of an animal.
- Make sure the animal offers a balanced set of information. Pay attention that you do not give up on some traits by focusing too much on others. For example, if you focus solely on growth, mature cow size will increase, which may be undesirable in your environment. This could result in reduced reproduction. Therefore, moderate EPDs in this category may be more appropriate.
- When purchasing a bull, make sure genetic testing has been done. A genetic test will improve the accuracy of an EPD. The more accurate the EPD the more likely those traits will be carried on to the offspring.
- Look at the animal. Visual appeal and structure are important and heritable.
Setting production goals, studying the EPDs, ranking the bulls in an offering based on your selection criteria, and keeping good records will all help in improving the production efficiency of a cow herd.