Researchers from the University of South Bohemia in the Czech Republic are proposing that common carp’s stored sperm samples can be warmed from 0-2°C to 20°C for more than 10 minutes before being used for in vitro fertilization. This strategy, which was tested both on a lab-scale and large-scale, improved sperm motility and fertilization success of refrigerated cells.

To assess the effects of elevating the temperature on sperm motility and fertilization ability, researchers stored sperm of common carp in an extender for 6-9 days at 0-2°C under aerobic conditions. After storage, the samples were incubated at 20°C for more than ten minutes to evaluate spermatozoa motility, straight-line velocity (VSL) and curvilinear velocity (VCL), viability, and fertilizing ability.

Results showed that incubation at 20°C has beneficial effects on spermatozoa viability or spermatozoa motility. However, despite elevating the temperature to 20°C for 10-20 minutes at three, six, and nine days post storage (DPS) promoted spermatozoa motility kinetics, researchers highlight that at 6 DPS spermatozoa motility was significantly increased by incubation at high temperature, as well as cells activation.

Moreover, at 9 DPS, results showed that fertilization and hatching rates were increased when the cells were incubated at 20 °C for 10 and 20 minutes at the ratio of 30,000 spermatozoa per egg. VSL, VCL, and viability dropped at 3 DPS when the activation was performed without incubation at 20°C.

This methodology was also tested in a large-scale trial, in a hatchery in which sperm stored for eight days was incubated for two hours at 20°C. According to the authors, this treatment also resulted in an increase in spermatozoa motility and fertilizing ability.

“This study provides a new strategy for handling short-term stored sperm as an efficient and effective method for carp artificial reproduction in a hatchery. This method may be worth pursuing in developing artificial reproduction in economically important fish species in aquaculture,” researchers concluded.

Reference:

Songpei Zhang, Yu Cheng, Sayyed Mohammad Hadi Alavi, Nururshopa Eskander Shazada, Zuzana Linhartová, Vladimíra Rodinová, Otomar Linhart. (2022) Elevated temperature promotes spermatozoa motility kinetics and fertilizing ability following short-term storage: An implication for artificial reproduction of common carp Cyprinus carpio in a hatchery. Aquaculture, Volume 565, 739126. https://doi.org/10.1016/j.aquaculture.2022.739126