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What is an accuracy of an estimated breeding value, and why do we publish it?
DR. BOBBIE VAN DER WESTHUIZEN & DR. JAPIE VAN DER WESTHUIZEN
he accuracy of an estimated breeding value
by the symbol h², heritability is a statistical concept that
(EBV) is a measure of how effectively it
quantifies the proportion of trait variation attributed to
represents the true breeding value of an
genetic variation within a particular population.
animal for a specific trait. The accuracy is always expressed as a value between 0 and
1, usually published as a percentage
Heritability estimates range from zero to one. A heritability close to zero suggests that the variability in a trait among animals is primarily influenced by
ranging between 0% to 100%.
environmental factors, with minimal contribution
In statistical terms, the accuracy
from genetic differences. On the other hand, a
of a breeding value is determined
heritability close to one indicates that the variation in a
trait is predominantly due to genetic differences, with
between the true breeding value
minimal influence from environmental factors.
of a specific animal for a given
For traits with higher heritability, obtaining
trait and the predicted (estimated)
breeding value based on the available information.
Conversely, traits with lower heritability
indicates a greater accuracy of the
breeding value and increases the
reliability of the estimated breeding
to achieve higher accuracy values.
value. Moreover, a higher accuracy
Therefore, it is possible to achieve high
means that the prediction is less likely
accuracies for low heritable traits when
to change as more information becomes
sufficient performance data is recorded
available. Accuracy is influenced by various factors, including the heritability of the trait, the accuracy of parent recording, the completeness of available performance
for all related animals of a specific individual. Obviously, the number of related animals increases significantly with more measured (recorded) progeny.
information, and the accuracy of measurements
associated with the performance data. Additionally,
dependent on the accuracy and completeness of an
the effective size of the contemporary group in which
animal’s recorded pedigree. Animals with meticulously
the animal and its relatives were recorded is another
recorded and complete pedigree trees are associated
with more precise breeding value predictions.
Heritability of a trait is a measure of the extent to which
differences in genes account for variations in the
recorded within the pedigree that truly contribute to
specific physical expression of that trait. Represented
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