Selection of dairy bulls on half-sister records

A scheme is described for the genetic improvement of milk yield in a large population of dairy cows, based on half-sister selection of young bulls, as an alternative to the normal procedure of progeny testing. The results indicate that the suggested scheme would lead t o an eventual rate of genetic progress very similar to the progeny testing scheme. However, the annual cost of the new scheme is less than a progeny testing scheme, largely because the ‘laying off’ of candidate bulls, to await selection, is completely eliminated. In addition, improvement of the dairy cows shows up sooner in the new scheme; by the 10th year from the start the cumulative genetic improvement is four times greater than for progeny testing.