Collection, storage and freezability of equine epididymal spermatozoa

The recovery of spermatozoa from the cauda epididymis may be the last chance to obtain genetic material from stallions undergone to castration. The aim of the current study was to evaluate the efficiency of cryopreservation and the use of two different extenders for equine epididymal spermatozoa. Testicles obtained from castration were divided into two groups: cauda epididymis processed immediately after orchiectomy and cauda epididymis processed after 24 h storage in saline solution at 4 °C of the testis. The epididymal spermatozoa were collected through manual slicing of the cauda epididymis of each testicle. In addition, spermatozoa obtained from different processed testes were diluted alternatively with either modified Palmer or EGG TECH® extenders to produce frozen straws. Motility parameters in fresh and frozen-thawed material were analysed by means of the computer-aided sperm analysis (CASA). The recorded CASA data were analysed with a mixed linear model. Motility parameters in fresh semen yielded better results than in frozen semen (p = 0.008), but no difference (p > 0.05) was observed between spermatozoa collected immediately after castration or after 24 h of storage; in frozen-thawed samples, EGG TECH® tended to improve the percentage of progressively motile spermatozoa in epididymal frozen-thawed semen (p = 0.08) compared with modified Palmer. We conclude that the processing of epididymal spermatozoa can occur up to 24 h after stallion castration and both common extenders used are suitable for preserving this material.