Economically Relevant Trait Selection

Consider when to use EPDs for indicator traits vs. EPDs for economically relevant traits.

by Kasey Brown, associate editor, Angus Journal^®

LINCOLN, Neb. (June 19, 2014) — “There has been a lot of time, money and effort invested in collecting data on economically relevant traits (ERTs), but not as much effort in how to use those data. That’s something we need to talk about,” said Bruce Golden, department head and professor of the Dairy Science Department at California Polytechnic State University–San Luis Obispo. He spoke to the joint meeting of the Advancements in Selection Decisions and Advancements in Producer Applications committees at the 2014 Beef Improvement Federation (BIF) Annual Meeting & Research Symposium in Lincoln, Neb., June 18-21.

Expected progeny differences (EPDs) are just parameters in the decision-making process in the beef industry, he said. However, they depend upon submitted data, so they are not complete. He recounted some of the history of performance records and EPDs. With the advancement of technology and trait data collection, the sire summary of the future could be huge. With too many options, though, breeding decisions don’t get easier.

That’s why ERTs have importance as selection tools. He illustrated two categories of traits, ERTs and indicator traits. ERTs are traits that directly affect profitability by being associated with cost or the income stream. Indicator traits have a genetic correlation to ERTs and can be used in analyses to increase the accuracy of ERT EPDs.

However, using the EPDs of indicator traits rather than ERT EPDs in selection decisions actually decreases the accuracy of that decision, and thus decreases the likelihood of making a good decision. Indicator traits are only part of the equation.

Not all traits are straightforward as being an ERT or indicator trait. Weaning weight can be either, depending on the situation. It is an ERT if you sell calves at weaning. If you sell calves as yearlings, the weaning weight EPD is an indicator trait. This is why indexes are helpful, explained Golden.

Should indicator traits be measured? Of course, he answered, but should they be published? For instance, the birth weight EPD is mostly an indicator trait for calving ease. On the other hand, he asked if indicator traits are not published, then will cattlemen continue to submit the data if they think indicator traits are less valuable?

He proposed only publishing EPDs that are used in any type of Partial Budget Decision Analysis, which predicts the financial impact of incremental changes in revenue and costs from alternative decisions.

Sire summaries have gotten better, Golden asserted. Enhancements include selection indexes, more fertility EPDs, elimination of ultrasound EPDs, and working toward a feed consumption EPD.

He likened decision analysis tools to the book and movie Moneyball. They can take the bias out of the decision and narrow the options down to the important traits. In the age of genomic data, decisions are complex and expensive. New models and methods allow new things, he added.

He concluded by recommending investment in production-level simulation models, both for producers and breeders. He added that what ERTs are produced completely depend on the models.

The 2014 BIF Annual Meeting & Research Symposium was hosted by the University of Nebraska–Lincoln, the U.S. Meat Animal Research Center and the Nebraska Cattlemen June 18-21 in Lincoln, Neb. The Angus Journal and LiveAuctions.tv provide comprehensive online coverage of the event at www.BIFconference.com. Visit the Newsroom for summaries, proceedings, PowerPoints and audio of the sessions; the Awards page for announcements of award winners; and the Photos page for galleries of photos from the meeting and the tours.

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