Successful ultrarapid cryopreservation of wild Iberian ibex (Capra pyrenaica) spermatozoa

Abstract A method for cryopreserving wild ibex sperm at high cooling rates was developed. To design a freezing solution based on Tris, citric acid, and glucose (TCG), two preliminary experiments were performed using glycerol (GLY) and dimethyl sulfoxide (DMSO) at different concentrations (5%, 10%, 20%). The 10% GLY + 10% DMSO combination reduced (P  in vivo fertilization involving domestic goats was performed to evaluate the in vivo fertilization capacity of the ultrarapidly cooled cryopreserved sperm (in TCG-ey + 100 mM sucrose), with warming undertaken at 60 °C. Inseminations of domestic goats resulted in three pregnancies (3 of 16, 18.7% fertility). In conclusion, ibex spermatozoa are strongly sensitive to high concentrations of permeable cryoprotectants and sucrose. However, the combination of ultrarapid cooling, using TCG-ey + 100-mM sucrose, and fast warming at 60 °C, followed by sperm selection by density gradient centrifugation to collect the motile sperm, has a positive effect on sperm viability.