Effect of Different Straw Volumes and Thawing Rates on Post-Thaw Quality and Fertilization Ability of Cryopreserved Common Carp (Cyprinus carpio) Sperm

Abstract

Cryopreservation of sperm cells is an essential process applied for long-term conservation of aquatic genetic resources. The goal of this research was to determine effect different of straw volumes and thawing rates on the post-thaw quality and fertilization ability of cryopreserved common carp (Cyprinus carpio) sperm. In this study, semen was cryopreserved according to conventional slow freezing protocol. For this aim, the cryosolution contained 75 mM NaCl, 70 mM KCl, 2 mM CaCl2, 1 mM MgSO4 and 20 mM Tris (pH: 8) supplemented with 10% MeOH. Following equilibration at +4 °C for 10 min, semen was packed into 0.25, 0.5 and 1.5 mL straws and frozen in liquid nitrogen vapour (for 10 min at -120 ºC) and finally stored in liquid nitrogen (-196 ºC) tank. Thawing of cryopreserved semen process was performed at 30 ºC for 10, 20 and 30 seconds in a water bath. Fertilization was performed using a ratio of 1x105 spermatozoa/egg. The highest fertility (68.4±2.5%) was determined with cryopreserved sperm packed in 1.5 mL straws that thawed at 30 ºC for 30 s. According to the results of this research, sperm cryopreserved with ionic extender containing 10% methanol and packed in 1.5 mL straws are suitable to achieve high fertilization of common carp eggs.