When performance fails to live up to breeding values

Discrepancies between estimated breeding values and livestock performance have led some farmers to doubt the accuracy of these values. They are, in fact, excellent indicators, but animals may not be able to reach their genetic potential.

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Using estimated breeding values (EBVs) is crucial in animal selection. Well-adapted, genetically superior animals perform better and are more efficient. Even though the environment plays a large role, it is the genetic value of a trait that determines the true potential of the animal.

Some farmers, however, are convinced that breeding values cannot accurately determine an animal’s genetic merit. A common inquiry is: “The progeny of a bull with average- or below-average breeding values perform well on my farm. Why is this superior performance not reflected in the bull’s breeding values?”

There are a variety of reasons for this. To begin with, an animal may fail to reach its genetic potential because the environment does not allow it.

In other words, an animal on your farm might have a lower breeding value than a similar animal in a herd elsewhere, but end up performing better because it is in a more favorable environment. These conditions enable it to reach its genetic potential, unlike the animal in the other herd.

VARIATIONS IN PROGENY

There are also a number of genetic factors that account for these anomalies. These are based on the way that DNA, the molecular hereditary material of all organisms, operates.