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One of the most exciting times of the year on cow-calf operations is when calves are born. Producers can see the results of their breeding decisions.

But experts from the Beef Cattle Institute at Kansas State University say it can be stressful and costly if those mating decisions lead to calving difficulties. That’s why care needs to be taken when planning those matings.

As bull-buying season approaches, selecting the right bull to match with heifers is important. Beef specialist Bob Weaber with Kansas State University-Extension said producers should begin by evaluating the type of breeding system they need to be successful.

“Think about what types of bulls you are going to turn out on what groups of females to define what the calving ease need really is,” he said.

One evaluation tool that producers can use in making that decision is the Expected Progeny Differences, which are the estimates of the genetic value of the parents to project the calf’s performance. They are estimated on a variety of traits among the beef breeds. The direct and maternal-calving-ease differences are often a consideration in heifer matings. The greater the number, the more reduced the risk for calving difficulty, Weaber said.

Calving-ease differences are expressed in percentage units of unassisted births. For example a bull with a calving ease of 12 is expected to have 7 percent more unassisted births from first-calf heifers than a bull with a calving ease of 5.

“Calving ease is one of the first things to think about when selecting the types of bulls to breed heifers,” said Dr. Bob Larson, veterinarian at Kansas State University.

But he cautioned that producers shouldn’t just isolate their decision to that one criterion.

Weaber said, “Selecting for very high levels of calving ease will lead to lighter calf birthweights over time, and could lead to calf-survival issues if taken to the extreme.

“A bull with a calving-ease (Expected Progeny Difference) of 20 will typically sire calves with a shorter gestation and lighter birth weight than a bull with a calving ease of 7. But there are potentially other problems to think about, such as a light-birthweight calf born in a snowstorm. The hypothermia issue is a much greater concern than the two assists a producer might have with a less-extreme (Expected Progeny Difference).”

He said Angus bulls in the 7-9 range for calving ease – breed average – matched with heifers will have an expected dystocia rate in the single digits. In other words the risk for calving difficulty is less.

It’s important for producers to find a balance in the traits.

“A small breeder who is going to use the same bull on the heifers and mature cows shouldn’t base the breeding decision solely on calving ease,” Weaber said. “They’ll be disappointed in the performance of the offspring from those matings.”

When speaking about performance, he’s referring to the growth traits in the calves.

If females born to first-calf heifers bred to calving-ease sires will be retained in the herd, Larson and Weaber both said cow-calf producers should include the maternal-calving-ease Expected Progeny Difference in their decision.

Another factor to consider is the time of year the calves will be born.

“Calves born in the summer or fall tend to be lighter calves than calves born in the winter due to the seasonality affect,” Larson said.

Weaber said producers should use all their mating-evaluation tools when planning for optimum herd performance.

“There has been enough advancement with genomics and selection that we can have really acceptable levels of calving ease with outstanding levels of performance,” he said. “Don’t immediately discount when buying a calving-ease bull the performance of the calves coming from that mating. We can have both pieces today.”

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This article originally ran on Content Exchange
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