Improving the Rabbit Semen Cryopreservation Protocol: Comparison Between Two Extenders and Inseminating Doses

This study has been designed to optimize the semen freezing protocol in rabbits. In this regard we compared a Tris-citrate-glucose (If G) extender with a commercial one (Cortalap (R)), that to the best of our knowledge has never been used up to now on the in vitro freezability and fertilizing ability of cryopreserved rabbit semen. Two different inseminating semen (loses were considered. Five pooled semen samples were divided into two subsamples and each of them were diluted to a ratio 1:1 (v:v) with a freezing extender composed of TCG or Cortalap (R) containing 16% of di methylsulfoxide and 0.1 mol/L of sucrose. The extended semen was filled into 0.25 mL plastic straws and frozen above a liquid nitrogen surface. After thawing (50 degrees C/10 seconds) we determined sperm motility, viability, membrane functionality, acrosome and DNA integrity. Our results showed that the Cortalap (R) extender significantly improved the in vitro post-thaw sperm quality, in comparison to T(X:. When we compared the extenders in vivo, no significant differences in the reproductive performances were observed independently by inseminating doses used. In this study we demonstrated that Cortaliqt extender can be used as an alternative to TCG. Thus, the Cortalait being a ready to use extender, implies a reduce of time, mistakes and microbial contaminations during its preparation. This discovery is significant because it provides an important contribution to the creation of the first Italian semen cryobank of rabbit breeds and also for livestock rabbit farms based on artificial insemination (AI) program.