This depends on what the actual Index values of the Bull and the Cow have. A High EBI Bull from the active bull list with an index of €338 and a low EBI Cow with an index of €12 will give you a calf with an index of €175. In this example we are able to breed a replacement heifer calf in the Top 25% from a cow that lies in the bottom 5%. This is called genetic gain.
The calf’s initial index is calculated by adding the index of the sire and dam together and dividing by two*. The above example shows us that breeding high EBI replacements can be achieved even if your cows do not have a high EBI figure to start with.
*Note this figure may be slightly different when calf is born as there will have been two to three genetic evaluations between time of breeding and calving (the parents figures may be slightly different by time of birth making the parental average slightly different).