ABSTRACT
We can boost the effective fecundity of males with artificial insemination. In dairy cattle, a single bull can father over a million progeny. This makes such individual bulls of critical value, and we must make every opportunity to select the best bulls. This can be done by starting in the previous generation with a mating strategy designed to produce elite young bulls, achieved by mating the very best cows in the land to the best available bulls. The resulting young bulls are progeny-tested for their milk traits, an example of matings set up to identify genetic merit, and the very best become the new champions. This is then a two-tier mating system with four pathways for genes to flow through-the elite tier with MM (males to breed males) and FM, and the commercial or base tier with MF and FF.
