Though they contain valuable information, EPDs are among many factors that go into decisions about sires
It’s impossible to say how many commercial cow-calf producers consider the expected progeny differences (EPD) statistics of bulls they plan to buy.
Dr. John Basarab, beef research scientist with Alberta Agriculture, suspects that it isn’t very many. He thinks EPD data is a few levels down on the list of bull-buying considerations.
First on that list is a bull that fits the herd’s management and environment.
Then it’s breed selection and desired characteristics.
Next is consideration of the breeding objective, whether to raise replacement heifers and expand the herd, or raise calves for the beef market. Maybe both.
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After that, reputation of the breeder comes into play; whether that breeder has similar management style or whether bulls purchased from that person in the past performed well in the buyer’s herd.
Then, and maybe only then, EPDs enter the equation.
“Some very astute cow-calf managers will look at a variety of EPDs, everywhere from calving ease to birth weight to weaning weight to yearling rate, even to dry matter intake and RFI, residual feed intake,” said Basarab.
He estimated about 85 percent of commercial cattle producers use purebred bulls, for which EPD data is available.
But when those bulls are used in a commercial herd, which may have a variety of crossbreds, EPD data is less reliable in terms of outcome.
“The EPD has been trained on a purebred population, so that’s fine. The genetic effect should still be there. But when I take it to an unknown crossbred cow, the predictability is down.”
The results of breeding an Angus bull to a mostly Angus cow are highly predictable, said Basarab in giving an example. Results from that same bull, used in a herd of crossbred Hereford, Angus and Simmental cows, are much harder to predict.
“The resulting offspring, their performance is going to be less than predictable from the EPD,” he said.
“The next thing is, hybrid vigour comes in there and messes things up.”
An Angus bull bred to a Hereford-Simmental crossbred cow will provide a big hybrid vigour boost, especially in fertility traits. EPDs won’t account for that. Unpredictable results like these, and other surprises, might be why relatively few commercial cattle producers rely on EPDs.
“Over the years, cattle producers observe this and maybe some of the more skeptical ones go, ‘EPDs don’t work.’
“Well, they work, but in a variable cross breeding program they may be less predictable, or there needs to be more variables coming into play before you can actually predict the performance of the offspring.”
The result is that cow-calf producers rely more heavily on what they know, what they’ve observed over the years and what they’ve learned from other experienced cattle people, said Basarab.
“We would hope that our EPDs would become more useful for commercial cattle producers and of course those are some of the things we’re working on.”
And although the quality of the Canadian cow herd has improved over the years, he said it has been relatively slow, especially compared to the dairy industry where genomic technology has been embraced.