Effect of extender compositions, glycerol levels, and thawing rates on motility and fertility of cryopreserved wild african catfish (Clarias gariepinus) sperm

Abstract

The aim of this study was to determine the effect of different extenders, glycerol levels, and thawing rates on post-thaw sperm motility and fertilization ability of cryopreserved African catfish (Clarias gariepinus) sperm. Having determined the main spermatological properties (volume, motility, motility duration, spermatozoa concentration and pH), the pooled ejaculates were diluted with 3 different extenders containing different glycerol levels (5, 10 and 15%) respectively. Dilution ratio was 1:10 and the diluted sperm was packaged in 0.25 ml straws and left for 10 min equilibration at 4ºC. Following equilibration, the straws were exposed to liquid nitrogen vapor for 10 min and plunged into liquid nitrogen (-196ºC), and then exposed to different thawing rates (30ºC/20s and 40ºC/20s) to determine sperm motility and post-thaw motility duration. The highest post-thaw sperm motility, motility duration, and fertilization rate was 85%, 81s, and 95% respectively when sperm was frozen with the extender (ACSE 3) containing 15% glycerol (p<0.05). The protocol reported in this study can be successfully used for cryopreservation of African catfish sperm. © 2017, Israeli Journal of Aquaculture - Bamidgeh. All rights reserved.