Intensity of selection
If in a population, we select the parents randomly, the genetic mean in the offspring population will be the same as the genetic mean in the parental population. However, the results in genetic improvement will not be the same whether the best 1 of 10, the best 5 of 10, the best 9 of 10 or some other fraction are selected. |  |
In dairy cattle, the use of artificial insemination has led to a very intense selection of bulls, as that truly herd-improving sires can be used in many herds and on many cows.
The following table gives factors associated with intensity of selection:
Select top percentage | Intensity factor | Comments |
|---|---|---|
100 | 0.00 | |
90 | 0.20 | Usual level for selecting cows in a herd |
75 | 0.42 | Maximum level for selecting cows in herd |
50 to 10 | 0.80 to 1.75 | Usual range for selecting dams of young bulls and of bulls out of young bulls sampled |
5 to 1 | 2.06 to 2.67 | Possible range of selection for dams and sires of young bulls |
