Comparison of the characteristics of chinchilla epidydimal semen after collection, storage at 5°C and cryopreservation.

The aim of the study was to compare the characteristics of chinchilla epididymal sperm: fresh, stored at liquid state and cryopreserved. Epididymal spermatozoa obtained from 11 males were assessed for subjective motility, concentration, motility parameters measured by CASA, viability, morphology, membrane integrity, acrosome integrity, mitochondrial potential, lipid peroxidation, chromatin structure, apoptotic changes and capacitation. Then half of the spermatozoa were stored at 5°C for 30 hr, and the second half was cryopreserved. After storage and thawing the same parameters as in fresh semen were assessed. Fresh semen showed good quality, with low levels of lipid peroxidation, chromatin fragmentation and capacitation. CASA evaluation showed significantly lower values for MOT, PMOT, RAPID, VCL, VAP and VSL after both storage at liquid state and cryopreservation (p < 0.05). Cold storage did not induce membrane and acrosome damage (p > 0.05), conversely to cryopreservation (p < 0.05). After storage, there was a drop in high mitochondrial potential in live cells (p < 0.05) and an increase in the percentage of non-apoptotic, capacitated cells (p < 0.05). These changes were not seen after cryopreservation (p > 0.05). Lipid peroxidation in live cells and chromatin structure remained unchanged both after storage and cryopreservation (p > 0.05). The study showed that examined methods of semen preservation exerted different patterns of changes in spermatozoa and that sperm quality after both of them allowed for further use of preserved spermatozoa in artificial reproductive techniques.