This disclosure provides a method for adjusting the maturation state of mammalian sperm for use in assisted reproductive technologies (ART). A mammalian ejaculate is provided and incubated under controlled conditions. Aliquots of the ejaculate are assayed during incubation period at intervals to determine maturation state and changes in the maturation state by observing the percent positive cells in the aliquot. The assays are repeated with successive aliquots at intervals during incubation to observe real time changes in the maturation state. The ejaculate remaining is processed for the desired ART after the percentage of positive cells in the latest aliquot being assayed begins to decline.