Application of artificial seminal plasma to short-term storage of a large volume of common carp (Cyprinus carpio) sperm for two weeks under controlled conditions

We previously demonstrated that artificial seminal plasma (ASP), developed for common carp (Cyprinus carpio), enabled considerable improvement of the fertilizing capacity of sperm in this species. Here, for the first time, the effectiveness of using ASP (ASP: 2 mM CaCl2, 1 mM MgSO4, 40 mM KCl, 100 mM NaCl, 20 mM Tris; pH 7.5 and 310 mOsm kg(-1)) for short-term storage of tenfold diluted sperm for up to two weeks at 10 degrees C was evaluated. Additionally, the fertilizing capacity of stored sperm was investigated. Sperm were stored in a volume of 5 ml in containers equipped with ventilation plugs enabling gas exchange of the stored sperm. During the study, the quality of the sperm was verified using the computer-assisted sperm analysis (CASA) system after 1, 2, 5, 9, 11 and 14 days of storage. After 14 days of common carp sperm storage in ASP sperm motility (MOT, %), the progressive motile sperm (PRG, %) and curvilinear velocity of sperm (VCL, mu m s(-1)) were confirmed to be 55%, 25% and 120 mu m s(-1), respectively. At the same time, in undiluted sperm (Control), we did not observe sperm motility. Only until the 2nd day of storage in undiluted samples motility and sperm kinetic parameters remained high level (84%, 34% and 144 mu m s(-1) for MOT, PRG and VCL, respectively). The fertilization of eggs and hatching rate after 14 days of sperm storage in ASP were 80% and 40%, respectively, and did not differ significantly from the fertilization and hatching rate determined after fresh sperm was used for fertilization. In summary, for the first time, the fertilization capacity of common carp sperm after 14 days of short-term storage under ASP conditions was confirmed, indicating the possibility of using previously collected and diluted ASP sperm in reproduction at a time convenient for the breeder. Thus, it is possible to reduce the stressful and time-consuming handling of fish during breeding under controlled conditions, which has an impact on the welfare of spawners.