Turning to sire selection for genetic gain is only a practical, logical business decision. Sire selection controls the flow of desirable genes into a dairy herd. The purpose of genetic improvement is to increase the frequency of good genes in a herd, not merely to combine mediocre genes in the least damaging way. Optimally, both benefits can be achieved by combining good sire selection with corrective matings. However, sire selection must come first.
Mate cows second.
Once traits to be improved by selection have been identified, the selection process can begin. A few simple rules are necessary. Make selection decisions on traits of major economic importance for which you have good estimates of breeding value. Predicted Differences for traits like milk and fat yield or some index of the two are examples. This allows the greatest possible selection intensity.