Effects of storage duration at 5 ºC and type of cryoprotectant on cooled and frozen-thawed ram epididymal spermatozoa

Freezing of ejaculated and epididymal spermatozoa is currently a subject of interest with the purpose of establishing an efficient gene banking model for valuable animals or endangered spe-cies. Therefore, the present study evaluated the influence of different storage duration )0, 1.5 and 5 h) at 5 ºC and type of cryoprotectant on freezability of ram epididymal spermatozoa. With increasing the storage duration from 0 to 3 h at 5 ºC, the motility, progressive motility, viability and recovery rate of stored spermatozoa decreased (P<0.05), but acrosome integrity and hyaluronidase activity were not affected (P>0.05). Addition of trehalose and sucrose to the basic diluent improved (P<0.05) the quality of frozen-thawed spermatozoa. Sperm motility, progressive motility, viability and hyalu-ronidase activity were higher in the present of DMSO than the control and BSA. There was no dif-ference in the acrosomal integrity between extenders. In conclusion, quality of froze-thawed sperma-tozoa was not improved when the extender was supplemented with sugar. However, further studies are needed to determine the fertility of frozen-thawed epididymal spermatozoa.