Characterization of epididymal spermatozoa motility rate, morphology and longevity of springbok (Antidorcas marsupialis), impala (Aepyceros melampus) and blesbok (Damaliscus dorcus phillipsi): Pre- and post-cryopreservation in South Africa

Cryopreservation of antelope epididymal spermatozoa could play a vital role in future breeding by developing a successful protocol for cryo-conserving them. The aim of this study was to characterize morphology, motility rates and longevity of epididymal spermatozoa from springbok, impala and blesbok. Cauda epididymal spermatozoa were collected post-mortem from both testicles of free-ranging springbok (n = 18), impala (n = 21) and blesbok (n = 21), and divided into two groups (pre- and post-cryopreservation). Spermatozoa were cryopreserved in Biladyl supplemented with 20% egg yolk and 7% glycerol under field conditions. Pre-freeze and post-thaw sperm quality was evaluated. The longevity of thawed spermatozoa was evaluated under culture conditions that support domestic cattle in vitro fertilization. There was a significant difference between pre-freeze and post-thaw sperm motility index (SMI) (p < 0.05), plasma membrane integrity (p < 0.05) and acrosome integrity (p < 0.05) for all species. Post-thaw SMI and plasma membrane integrity were comparable between species (p > 0.05). The effects of cryopreservation on sperm cell morphology differed between species and between specific abnormal morphology. Blesbok had the least abnormalities in post-thaw spermatozoa. Cryopreservation substantially reduced the survivability and motility rates of antelope species. Blesbok spermatozoa tolerated cryopreservation and thawing process better than impala and springbok. The antelope cauda epididymal sperm maintained viability and acrosome integrity for at least 4 h following incubation under conditions that support domestic cattle in vitro fertilization (IVF) with a decline in longevity over time across species however; species responded differently over time in terms of plasma membrane integrity and acrosome integrity. The antelope species may have different in vitro culture requirements, indicating differences in sperm physiology between the species. This research could contribute species-specific protocol development for IVF thus promoting ex-situ conservation strategies of African antelope species in South Africa.