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An Estimated Breeding Value (EBV) predicts the breeding merit of an animal for a specific trait. The degree to which this EBV reflects the “true” breeding merit of the animal depends on how much we know about its performance relative to the rest of the population.

Accuracy Values indicate how much we know about an animal and its relatives for a specific trait.

Why Accuracy Matters

Accuracy Values indicate the likelihood of an EBV changing (up or down) as more information on the animal becomes available.

Accuracy Values account for the risk involved in making breeding decisions and provide buyers with the confidence that an EBV is accurate.

For any trait, the accuracy of the EBV is influenced by several factors:

  • Amount of information for the animal
  • Amount of information from relatives
  • Heritability of the trait
  • Amount of information from traits correlated with the trait of interest and the strength of these correlations
  • Number of animals being compared (contemporaries.

Animals With High Accuracy Values

Selecting breeding stock with high accuracy values minimises the risk when making breeding decisions. Widely used stock sires, e.g. reference rams with lots of recorded relatives, will have high accuracy values. Fully recorded ram lambs with lots of recorded relatives will have acceptable accuracy values.

Animals With Low Accuracy Values

An important feature of Signet’s breeding evaluations is that they are risk averse. EBVs based on limited amounts of information get adjusted back towards an average figure until more data becomes available.

Amongst those animals with low accuracy values there may be individuals with good genetics, but a lack of performance data means they are difficult to identify using EBVs.


Accuracy values indicate how similar an animal’s EBVs are to its true breeding value
Breeders can use accuracy values to predict the likelihood that an animals EBVs will change over time.

More information is provided in our fact sheet  Accuracy values in sheep breeding evaluations