A new approach for cryoprotectant-free freezing of goat epididymal spermatozoa.

A cryoprotectant-free method was successfully used for rapid freezing of goat epididymal spermatozoa. Lowering sperm volume may increase the temperature exchange rate and improve the freezing output of spermatozoa. The aim of this study was to compare two different packaging types [0.25 ml French straws (FS) and 96-well immune plate (WIP)] for rapid freezing of goat epididymal spermatozoa. Eleven pairs of the goat testes were transferred to the laboratory; cauda epididymidides were dissected and sliced in TRIS-BSA solution for 15 min and temperature 33-35 °C. Sperm concentration was adjusted to 20 × 10(6) ml(-1), and the suspension was subjected to rapid freezing within FS or WIP. The volume of spermatozoa in WIP method was set at 25 μl. Sperm motility, viability and abnormalities, and sperm DNA integrity were compared between two devices. The results showed similar effectiveness of WIP and FS on post-thaw sperm parameters. In conclusion, for cryoprotectant-free rapid freezing of goat epididymal spermatozoa, it is recommended to use WIP instead of French 0.25 ml straws.