Use of Equine Sperm Cryopreservation Techniques as a Conservation Method of Donkey Germplasm

The aim of this study was to test equine semen cryopreservation techniques for the conservation of donkey germplasm. Ejaculates of three male donkeys were used (n = 18; six ejaculates per donkey; six repetitions), collected by the artificial vagina method. To remove the seminal plasma, the ejaculates were split and submitted to filtration or centrifugation methods. To assess the freezing method, each fraction was submitted to the automated system or the conventional system, and groups were formed: automated centrifuge, automated filtrate, conventional centrifuge and conventional filtrate. After thawing (37°C/30 seconds), were analyzed the sperm kinetic parameters, integrity and functionality of the plasma membrane and mitochondrial membrane potential. Highest sperm concentration (P < .05) was observed in the filtrate groups; the conventional filtrate group presented lower (P < .05) progressive motility and curvilinear velocity compared to the other groups; no difference was observed (P > .05) among the groups for the membrane integrity and functionality, and mitochondrial membrane potential. Thus, centrifugation is the most indicated technique to remove donkey seminal plasma and the automated and conventional freezing methods can be used in donkey semen conservation.