The role of seminal plasma in the liquid storage of spermatozoa

Ongoing progress in proteomic characterization of seminal plasma has stimulated research on the identification of biomarkers for male fertility and sperm preservability. So far, many studies have evaluated the benefits of reconstituting cryopreserved or sex-sorted semen with seminal plasma. Less information is available about the effect of remaining or added seminal plasma in liquid preserved semen. The interaction between seminal plasma and spermatozoa is species -specific, and within species often complex and ambiguous. This article aims to review the action of seminal plasma on sperm function in preserved semen with a focus on liquid storage. Effects of seminal plasma on sperm traits during in vitro storage are summarized for males from four domestic farm animals, namely the bull, ram, boar and stallion. Special emphasis is placed on the effect of seminal plasma on long-term stored boar semen, including novel data demonstrating the attenuating effect of protective extender on the adverse effect of seminal plasma in some boars.