Boar seminal plasma proteins and their relevance to reproductive technologies

Abstract

Seminal plasma proteins participate in a number of events important for fertilization and the establishment of pregnancy. As a result, attempts have been made to use them to enhance reproductive performance associated with several swine reproductive technologies. Inclusion of seminal plasma into cryopreservation and sex-sorting protocols improved sperm viability and membrane integrity and suppressed capacitation-like changes which are considered to be major challenges associated with these techniques. Unfortunately, it has yet to be shown that these improvements consistently increase in vivo fertility. In contrast, pre-breeding administration of seminal plasma in conjunction with conventional breeding regimens improved farrowing rates and numbers of pigs born alive on commercial farms that already had very good reproductive performance. The best way to capture these beneficial effects in A.I. programs currently is being investigated. Finally, three seminal plasma proteins appear to have reasonable correlations with fertility in boars that normally produce sperm with excellent motility and morphology. They hold potential for development of prospective male fertility tests. However, there is some evidence that indicates consideration of the complete profile of a boar’s seminal plasma proteins may be more appropriate for this purpose as opposed to concentrating on individual ones independently. Preliminary results from a field study indicate that farrowing rate and litter sizes are superior in boars with high levels of two seminal plasma proteins associated with fertility compared with their counterparts in which only one of these is elevated. All of these technologies will benefit from continued research efforts devoted to the additional characterization of proteins in seminal plasma and elucidation of their biological effects on swine reproductive physiology.