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♦ Selecting for Soundness
♦ Selecting for Soundness

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By Kayla M. Wilkins

Historically, the cattle industry was almost entirely driven by phenotypic selection alone. Cattle producers weighed selection heavily on structural evaluation because it was the primary tool available.

The progressive nature of the industry has resulted in a shift in the selection process over the last few decades.

Today, genomic data are a major player when it comes to selecting seedstock and females for a productive herd. Although this progression has been a positive addition, Kansas State University Associate Professor and Extension Specialist Bob Weaber claims the progress has also created obstacles.

"I suspect in some ways maybe that's contributed a little bit of a challenge to us, in terms of now we have so many things to select for," Weaber says. "We've only got so much selection pressure we can apply. Maybe we've diluted that a little much and avoided some selection for traits that have a functional connotation to them that maybe we should think about."

From the Ground Up
While using expected progeny differences (EPDs) for selection is a proven valuable tool available to producers, it is important to not neglect the value in visually evaluating potential seedstock for foundational soundness.

"I think the set of the hock and the angle of the shoulder, fundamentally, are two things to understand and are very important to look at," says Shane Bedwell, American Hereford Association (AHA) Chief Operating Officer and Director of Breed Improvement. "Ultimately, they can affect the size of the foot, and the shape of the foot."

Starting from the front, Bedwell says, the angle from the top of the shoulder to the point of the shoulder and from the point of the shoulder to the elbow should ideally be sloped at 45 degrees – or fairly close. When the angle exceeds the 45-degree threshold, problems can occur.

"Those animals are too straight in their front end," he notes. "They lose mobility, and what's going to happen is the front toes are going to grind down because they're not wearing down correctly."

For Bedwell, the rear structure is just as important as the front, particularly when selecting breeding stock. He says maintaining a 45-degree angle from the top of the hip bone to the point of the hock aids in creating longevity within a herd.

A fundamental, but crucial, piece that Bedwell says is sometimes overlooked is heel depth. When evaluating yearling bulls to take home and put on cows, Bedwell highly advises producers to take heel depth into consideration – especially from a longevity standpoint.

"If there's not enough depth of heel and strength in the pastern, what happens to this foot? It starts to grow out," he explains. "If we don't have the right foundation, the right depth of heel here, we're going to run into some serious problems."

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Keeping phenotypic evaluation in mind, Bedwell advises producers to use the best combination of resources for them from a genotypic and phenotypic standpoint.

"We've got to do a better job of selecting those animals – of selecting breeding cattle that don't have those problems," he says. "I know some of it is environment, and some of it's genetic. I'm excited being able to see some of these different EPDs come out."

Looking Ahead
As scientists continue conducting research to best develop selection tools for the producer, the phenotypic structure component has been receiving some attention.

"The good news from a breeding genetics standpoint is we have a real opportunity to make some selection progress from these traits," Weaber says. "One of the obvious questions is why do we need genetic improvement tools for feet and leg traits?"

On the forefront of reasons for this expansion of research are welfare and economics. On the economic side, there is a financial penalty associated with buying an unsound bull.

"If you buy a $4,000 or $5,000 yearling bull and next year he isn't breeding cows because he's got bad front feet, that's a big problem." Weaber explains. "I think there's some pretty clear data that lots of productivity and soundness are certainly good motivators to think about improving the structural capabilities of our seedstock."

Moving forward, a selection index incorporating feet and leg structure is not far away. In fact, there has already been dramatic progress in developing those tools, and there is the prospect for even more genetic improvement in this area.

For instance, the dairy industry has done a lot of work with feet and leg structure as it relates to extended longevity. Weaber says the progress in the dairy industry has translated to the beef industry.

Australian Angus has been working toward determining the heritability of structural traits in recent years, and his team at Kansas State is expanding upon that idea.

"We want to look at culling data in association with other production traits, as they relate to these feet and leg characteristics – also growth rates, dense data recording and post screening gains," he notes. "How those are developed certainly has an impact on their long-term stability and performance in terms of feet and leg structure – ultimately breeding soundness. We plan to look at that as well and incorporate some genomics work when we can."

Originally published in the March 2017 Hereford World. Reprinted with permission.


September 2018


 
 
 
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