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Estimated Breeding Values (EBVs) provide a measure of the breeding potential of an animal for a specific trait. They take into account performance data collected on known relatives, the relationships between performance traits (correlations) and the degree to which traits are inherited from one generation to the next (heritabilities).
EBVs are expressed in the same units as the recorded trait (e.g. kg for 200-day weight) and they relate to a common baseline (usually set in 1980).
EBVs are easy to interpret, for example:
A bull with an EBV of +40 for 400-day weight is estimated to have progeny with the genetic potential to be 20kg heavier at 400 days of age compared to a bull with an EBV of 0.
A recorded bull will only pass on half of its genes to its calves so its EBVs must be halved in order to estimate the average genetic worth of its progeny
What is a Breeding Index?
EBVs aid the selection of breeding stock according to specific traits and they can also be combined into selection indexes to meet wider breeding objectives with economic benefits included.
An index is an overall score of genetic merit combining the relative economic values of several EBV traits. Stabiliser cattle use five selection indexes:
The economic value of an animal in terms of the financial merit of its offsprings’ carcases
The economic value of an animal in terms of gestation length and difficult calvings
The economic value of an animal’s genetic ability to produce breeding females
The economic cost associated with mature size
The economic value of an animal in terms of its genetic potential to produce females for breeding and animals with beef carcase characteristics, calculated from the four sub-indexes listed above.