New developments in estimated progeny differences (EPDs) promise to make them even more accurate and valuable tools for cattle producers. But, Brett Barham noted, they’re still not going to be perfect.
Barham, a University of Arkansas animal science professor and Extension specialist in beef cattle breeding and genetics, told Ozarks Farm & Neighbor the most promising addition to the EPD portfolio is a technique called “genomically enhanced EPDs.” He explained, “Since we have commercially available genetic markers that give us information about some of these same traits that EPDs predict, a lot of breed associations are taking this genomic information and incorporating it into the EPD as they calculate.” This makes the figure much more accurate, he said, even with a young bull that has few or no progeny on which to base the projections.
Another fairly new development, said Barham, is EPDs for feed efficiency “that try to help producers select animals that, for the same amount of feed that they eat, are going to give you a little higher level of production. Those are just starting to become more prevalent in many breeds.” Often, he said, when a breed association decides to add a new EPD to its book, it starts from the grassroots – producers who feel a trait is important to them, and relay the request to the association’s upper echelons. They, in turn, ask scientists whether the trait can be accurately reflected in an EPD. “Generally,” he said, “the biggest holdup on creating new EPDs is the science behind it, to make sure what we’re selecting for, how we’re calculating EPDs is really what we want.”
The most popular EPDs for commercial cowmen, Barham said, remain those that reflect the likelihood female offspring will produce a good, marketable calf. “We still want to have heavy weaning weights,” he said,  “We want to have females that have some maternal traits associated with them,” although those EPDs are more important to a producer who’s going to hold back replacement heifers than to one who will sell all of the bull’s offspring as terminal calves.
“Those traits have had EPDs available to them for awhile,” Barham continued. “We do have a few producers that are putting more selection pressure on some carcass characteristics; that’s probably become more prevalent over several years. But still, the majority of our cattle are what I would call commodity calves; they’re just sold at weaning.”
The amount of data available on each bull, and its accuracy depends on a couple of factors; larger breed associations like the American Angus Association register and collect information on many more animals across the nation than do some of the smaller, lesser-known breeds, which does help in some of the accuracy. For an individual bull, it’s all about the number of its progeny that have been recorded. “If he’s an AI sire,” Barham pointed out, “he’s going to have much, much higher accuracy than a yearling bull that may not have any progeny out of him at all.” Where some breeders like to stick with bloodlines that have worked for them in the past, others are more open to “whatever they find that suits their fancy at that time,” as Barham put it.
But the key to working with EPDs is to recognize what you’re getting; as with all predictions, there’s a degree of uncertainty. Barham said,  “Sometimes, you’ll hear people who say, ‘I thought I was buying a really good bull by his numbers, and he didn’t turn out to be what I was expecting.’ Some of that is probably warranted; EPDs are not 100 percent accurate, especially on a young bull. There’s quite a bit of chance for some error. But largely, I think some of that is people not understanding exactly what an EPD tells you. The definition of an EPD is the average performance of this bull’s offspring are going to be X number of pounds heavier or whatever trait you’re looking at; that doesn’t guarantee that every one of his progeny are going to be 2-3 lbs heavier than the other bull you’re looking at.”


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