Reproductive management of dairy cows has advanced significantly in the past two decades with the advent of ovulation synchronization protocols, improvements in nutrition and cow comfort, and the incorporation of female fertility and longevity traits into selection programs.

The selection of replacement heifers in commercial dairy farms has been traditionally characterized by very low intensity of selection, because in general farmers retain nearly every heifer calf as a future herd replacement. However, recent improvements in herd management have reduced involuntary culling rates and improved reproductive efficiency, which has led to the ability to produce excess heifers.