Easy EPDs

Data is plentiful in the cattle business these days. Breed associations carry, and regularly update, EPDs (expected progeny differences) on an ever increasing number of traits. Want to see EPDs on marbling? Feed efficiency? Yearling weights? It's all a mouse click away.

For many commercial cattlemen, a common goal is to have as many calves as possible born without difficulty, a trait referred to as calving ease. Bulls used on heifers play a big role in calving ease. Producers used to judge bulls on birth weight EPDs, as well as on actual birth weight. But today's calving-ease EPDs tell a more complete story, said Matt Spangler.

"If the goal is to decrease calving problems, the correct EPD to use is the one for calving ease," said Spangler, Extension beef genetics specialist at the University of Nebraska-Lincoln.

"Birth weight is an indicator of calving ease. But it doesn't tell the whole story. Calving ease takes out the environmental element, and lets us focus on genetics as an indicator of whether or not calves sired by a particular bull are more, or less, likely to need assistance to be born."

GETTING COMFORTABLE

Birth weight EPDs have been around longer than calving-ease EPDs, so Spangler said some producers may be more comfortable with that data set. He cautions against using both birth weight EPDs and calving-ease EPDs, as this doubles the emphasis on this one trait.

Spangler said there are still a number of producers who won't use EPDs at all, but prefer to know the weight of the bull when it was born. That information, he cautioned, can be misleading.

"If I know what a bull weighed when it was born, and I use that to determine which bull to buy for my heifers, I'm not getting the whole picture. The bull's actual birth weight takes into account some genetics, but there are a lot of environmental influences too. What was the age and nutritional state of the dam? What region was the bull born in? Birth weights tend to increase in colder climates. A sire can't pass on the environmental element, so they need to be selected on genetics."

CALVING-EASE DATA

There are two types of calving-ease EPDs. The calving-ease direct (CED) EPD indicates the percent of calves out of an animal expected to require assistance at calving. This is based on a two-year-old heifer. If one bull has a CED EPD of +10, and a second bull has a CED EPD of +2, the first bull would be expected to have 8% more calves born without assistance.

The second type of calving-ease EPD is the calving-ease maternal (CEM) EPD. This refers to how a bull's two-year-old daughters will perform. Sometimes this is called "daughters' calving ease." This can be valuable knowledge for cattlemen growing replacement heifers.

Spangler said cattlemen can use the CED EPD, the CEM EPD or both together.

"You can factor both the calving-ease direct and the calving-ease maternal EPDs into your selection process," he explained. "There is a slight negative correlation between the two. So know that if you increase or improve your calving ease direct percentage, you may see a slight potential for decrease in the calving ease maternal percentage."

Spangler said this makes a case against selecting for the same trait year after year after year, to the exclusion of other traits.

"When using EPDs the key is to evaluate your herd regularly and decide what your objectives are. If you are not seeing calving difficulties in your herd, for example, then maybe you put more attention in other areas. That evolves over time. A good way to really practice that is to use multiple trait selection and economic index values. These will take into account multiple traits at the same time."

Breed associations are the best places to get the most current EPDs available. Spangler said if you don't know the breed average, you can't judge EPDs for any trait. So be sure to have the most current information.

"Lastly, there is some confusion as to what EPDs really do for us," he said. "They are good indicators, no question there. But this is an average and a comparison. There will always be outliers. Some EPDs are higher in accuracy then others."

He explained: "Yearling bulls have lower accuracy EPDs than those AI bulls with a lot of progeny information on records. So there's more risk in using a yearling bull. My advice if you're buying a yearling bull and you need good calving ease is to select bulls that are a little above the breed average on that trait. That gives me more faith that their true EPD will be above the breed average. Also consider genotyping that yearling bull. The accuracy is equivalent to bulls with progeny. The added information will cost more, but it offers you a big advantage."

FINDING EPDs

Links to breed association websites can be found at www.beefusa.org under the "About Us" tab. The breed associations list Expected Progeny Difference (EPD) information under "sire summaries". Here you'll find breed averages and comparisons.

To compare cattle across breeds, go to www.ars.usda.gov and search for "Across Breed EPD Table". The information is updated annually and includes data for 18 of the country's most popular beef cattle breeds.

(VM/CZ)

Copyright 2014 DTN/The Progressive Farmer. All rights reserved.