Semen extender type and cold storage of tissue affect cryosurvival of alpaca epididymal sperm

Abstract

The objectives of this study were to determine the ability of liposome- and DMFA-containing semen extenders to support cryosurvival of alpaca epididymal sperm, and to evaluate the effect of epididymal cold storage on post-thaw viability. It was hypothesized that both semen extenders provide appropriate cryoprotection, and post-thaw sperm viability does not differ when alpaca epididymal sperm are cryopreserved immediately after castration or after 24 h of cold storage. Sperm were recovered from one epididymis from each male (n = 10) on the day of castration, and from the other one after 24 h of tissue storage at 4C. On each day, each sample was divided into two aliquots, which were cryopreserved in semen extender OptiXcell or BotuCRIO. Pre-freezing sperm parameters did not differ between samples obtained on the day of castration or 24 h later. Motility of sperm cryopreserved in BotuCRIO on the day of castration did not differ from pre-freezing values. Use of OptiXcell or delaying sperm cryopreservation decreased total (p = 0.002) and progressive sperm motility (p = 0.041) compared with pre-freezing values seen in sperm recovered on the day of castration. Membrane integrity was lowest when sperm were cryopreserved in OptiXcell after cold storage. Treatment had no effect on DNA integrity. It was concluded that the DMFA-containing semen extender BotuCRIO was superior to the liposome-containing semen extender OptiXcell at preserving post-thaw viability of alpaca epididymal sperm. Cold storage of epididymides for 24 h negatively affected post-thaw motility and membrane integrity of sperm. Therefore, cryopreservation with BotuCRIO immediately after castration is recommended for best preservation of post-thaw viability of alpaca epididymal sperm.