effects of storage duration at 5 °c 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 species. therefore, the present study evaluated the influence of different storage duration (0, 1.5 and 5 h) at 5 °c and type of cryoprotectant on freezability of ram epididymal spermatozoa. with increasing the storage duration from 0 to 3 h at 5 °c, 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 spermatozoa was not improved when the extender was supplemented with sugar. however, further studies are needed to determine the fertility of frozen-thawed epididymal spermatozoa.