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A Practical Guide to Bull Selection

Expected progeny differences are the most informative selection tool.

RUIDOSO, NEW MEXICO (Aug. 30, 2018) — As a transplant from Florida, Alabama and Georgia to Kentucky, Darrh Bullock told cattlemen gathered for the Applied Reproductive Strategies in Beef Cattle Workshop in Ruidoso, N.M., Aug. 29-30, that he would not tell them how to select bulls. Instead, he would offer a basic outline of how to approach the bull-buying process through the use of expected progeny differences (EPDs).

Rather than trying to evaluate actual measurements, performance ratios, genomic scores and EPDs, the University of Kentucky’s Darrh Bullock recommends producers focus on a bull’s EPDs, which factor in the other three.

“Bull buying is a process, and that process to find the right bull for your operation is consistent across the country, the world even,” Bullock said, noting that while the process is the same, the ideal bull isn’t. “There is no one formula. What works for you is not necessarily right for your neighbor.”

Some things need to be established before the bull-buying process begins, the University of Kentucky Extension beef geneticist said. An operation’s marketing strategy and management level should be major considerations when contemplating the best bull to optimize a program.

“The marketing strategy of your operation is the first determination of the characteristics you will look for in a bull,” Bullock said. For example, the decision to keep replacement heifers adds an additional job for a bull. Finding a bull that can throw both feeder calves and replacement heifers can be tricky.

When looking at a bull, you typically have a plethora of information to comb through. This includes actual measurements, performance ratios, EPDs and genomic information.

“I will argue that EPDs are the single line of information you need to look at,” Bullock said. “All three of those [other] things go into the calculation for an EPD. They are the one thing that looks at everything and puts it all into perspective.”

Trying to look at each of the four items individually, as well as collectively, reduces the accuracy of your selection process, Bullock emphasized. “The pedigree and performance data computed into an EPD take out environmental factors, so when comparing two bulls from that information, it is all based on genetic merit.”

EPDs are truly the best tool for selecting a bull based on performance because they incorporate all valuable information into the calculation, Bullock said. However, it is not a perfect system.

Bullock encouraged all producers, commercial and seedstock, to pull DNA on their animals and send it to their breed association for analysis. This will increase the amount of data for comparison, ultimately increasing the accuracy and precision of data generated on animals of all breeds.

History has proven EPDs work, Bullock said, showing graphs plotting genetic trends for various traits by breed. However, selection for one trait often caused changes in other correlated traits, and sometimes those changes weren’t ideal.

When he was a kid, buying an Angus bull was a surefire way to “select” for calving ease, recalled Bullock. What producers did not know was how some genetic traits were linked. By continuously selecting for growth, mature cow size also increased.

“Bigger cows eat more. We found out later that there is a cost for increased growth,” Bullock explained. “Weight determines how much a cow will eat. That is something we will need to use EPDs to get control of.”

The most underutilized tools in genetic selection, said Bullock, are the EPD percentile tables. These tables allow a producer to find where their bull ranks within the breed based on their EPDs. While a calving ease direct (CED) EPD of 14 might not provide much perspective, knowing the bull ranks in the top 10% of the breed for calving ease does.

Bullock cautioned cattlemen that within-breed EPDs are not directly comparable across breeds. However, the U.S. Meat Animal Research Center at Clay Center, Neb., annually calculates adjustment factors to calculate across-breed EPDs (AB-EPDs) that can be compared. You can find those adjustment factors, along with an explanation of how to use them, at

For details on Bullock’s presentation — including the proceedings, PowerPoint and video of his presentation — visit the Newsroom at

Editor's Note: This article was written under contract or by staff of Angus Media. To request reprint permission and guidelines, contact the Angus Media editorial team at 816-383-5200.