I know I’ve stressed several times before – and yes, I’ll stress it again – the crucial importance of sire selection and bull purchase. I even went so far as to dub it “the second-most important activity to ranching success,” – the most important being employee development.
During this process, Expected Progeny Differences (EPDs) – especially genomically enhanced (GE-EPDs) – are one of the most useful tools cow/calf producers have at their disposal. The importance of selecting and purchasing the right bull for commercial (and purebred) operations is absolutely paramount.
Yes. You read that right. I am, in fact, proposing even commercial operations use EPDs in sire selection. In the past, the perception was that EPDs were only for the “purebred folks,” or the bigger-volume producers. Not so anymore. This change emerged primarily due to the evolution of the beef industry; now – more than any other time in history – the industry covets data.
As a result, more and more bulls are sold with EPD information. This is a positive change as it provides an additional tool for the toolbelt of a potential buyer, helping to ensure they will be happy with the results of the bull they purchase. However, it’s my contention that – because EPDs are now so prevalent in our industry – we casually reference them in conversation without really knowing what they are… and, more importantly… how to properly use them.
Simply put, EPDs are an estimate of how certain traits of a bull will perform when compared to those traits of another bull – each within a particular breed and when bred to similar females. Mind you, all of this is before the mating process ever occurs! Let me just add – this is where I’m thankful women don’t have access to EPDs for their potential mates… particularly my wife.
The actual EPD is calculated using information submitted to the breed associations. It provides a basic representation of the pedigree for that particular bull for a particular trait of interest. It’s imperative you realize EPDs are not static; as more and more progeny information is collected, they will change over time… which leads us to yet another term of interest: accuracy.
Accuracy is just that: how accurate or reliable is an EPD? The metrics are charted on a scale from 0 to 1 – the higher the number, the more accurate the prediction. Accuracies are important when assessing existing bull batteries that may have animals of varying ages, or when looking at pedigree information. However, most of the pool of animals you will select from will be relatively young, not yet having produced any progeny. Therefore, they will have relatively low accuracies for their individual EPDs. This is where returning to looking at pedigree EPDs and accuracies against potential purchases becomes useful.
The process involves outlining your goals and objectives for each particular purchase. This will enable you to hone-in on specific traits most important to your operation, therefore allowing you to select a bull which meets those objectives.
For example, let’s assume you’re a producer who places priority on weaning weight. Within the breed you’ve chosen, you have two bulls from which to choose that will complement your cow herd. We’ll say the Weaning Weight (WW) EPDs for Bull A and Bull B are 31 pounds and 46 pounds, respectively, and their accuracies are roughly the same.
What does this mean?
It means – on average and when bred to a similar set of cows – Bull B will sire a calf that will wean 15 pounds (46-31) heavier at the same age than a calf sired by Bull A will wean. That’s all well and good, but… is that a good thing or a bad thing? Well, first, we need another very important piece of information: the percentile breakdown chart.
This chart is found in the sire summary for the breed of choice and allows you to look at the breed as a whole, as well as determine where an individual’s EPD fits within the breed. Remember: in the past, single trait selection has gotten us into trouble, and we don’t want to revisit that history. To avoid any extremes in any one trait, before making any purchase, be both aware and comfortable with all the bull’s EPDs which are important to you. If we know how to use them, acknowledge their limitations, and – if used in conjunction with other pertinent information – EPDs are a tool that can help make us better managers. If you’re interested in learning more about them, I strongly suggest, prior to purchasing any bull, you pick up a sire summary for your breed of choice and familiarizing yourself with it.