SPERM CRYOPRESERVATION OF IMPORTED COMMON CARP (Cyprinus carpio) IN LIQUID NITROGEN

Abstract

Common carp is one of the most important cultured freshwater fish in the world and Vietnam. The objective of this study was to determine the optimal conditions of extender, dilution ratio and freezing method in sperm cryopreservation of two imported common carp (Cyprinus carpio) strains (Szarvas P3 and Tata) from Hungary. Sperm were diluted in different extenders (Kurokura 2 solution and grayling solution with glucose) at dilution ratios of 1:3 and 1:8 (semen: extender) and were frozen using two freezing methods: controlled-rate programmable freezer or above liquid nitrogen vapour. The results showed that using Kurokura 2 extender with dilution ratio of 1:8 (semen: extender), 10% methanol and programmable freezer (from 4°C to -4°C: 4°C min-'; -4°C to -80°C: 11°C min-', and from -80°C they were plunged directly into liquid nitrogen) after stored for 1 month has the highest post-thaw motility (p<0.05) of two strains at 80.8% (Szarvas P3 strain) and 78.3% (Tata strain) compared with fresh sperm 85.8% và 85.4%% respectively.