Evaluation of frozen thawed cauda epididymal sperms and in vitro fertilizing potential of bovine sperm collected from the cauda epididymal

In the present study، the fertilizing potential of semen recovered from slaughtered bulls epididymis was evaluated after cryopreservation، by conventional techniques and flow cytometry methods. The cauda epididymal was dissected and sperm were recovered and evaluated for volume، sperm concentration، and membrane and acrosome integrity using a flow cytometer. Sperm fertility potential was tested by in vitro fertilization (IVF). For each bull، three trials of IVF were performed. Before freezing، on average، the sperm concentration was 216 ± 27. 5 × 106 sperm/ml. Sperm viability averaged 86. 5 ± 4%. The mean percentage of sperm with intact plasma membrane and acrosome before and after cryopreservation was 90. 7 ± 2. 9% and 90. 8 ± 1. 9% (P≥0. 05)، respectively. The fertilization rate using frozen/thawed epididymal semen averaged 64. 1 ± 3. 9% fertilization with no significant differences between bulls (P>0. 05). For the bull considered as control، the fertilization rate was 72. 2 ± 4. 5%، differing significantly (P>0. 05) from the frozen/thawed epididymal semen’s fertilization rate. In conclusion، it is possible to use in vitro techniques with cryopreserved spermatozoa obtained from bull’s epididymis using a controlled rate freezing method with a predetermined freezing curve، and with assessment of sperm’s viability by conventional techniques and flow cytometry methods، together with the fertilizing ability of cryopreserved epididymal spermatozoa.