Comparison Between Three Cryoprotectants in the Freezing of Semen Collected by Artificial Vagina.

Maintaining genetic variability is an important part of the conservation of endangered species, so the construction of germplasm banks is essential. Several species of the genus endure constant pressure in their natural habitat and are threatened with extinction. The correct manipulation and adequacy of the diluents and cryoprotectants must be studied to be successful in the formation of these banks. The purpose of this study was to evaluate the efficiency of three different cryoprotectants in sperm cryopreservation in the species : 6% glycerol (GLY), 3% ethylene glycol (ETG), and 5% dimethylformamide (DMF). Semen was obtained with the lateral deviation of the penis to an artificial vagina. In the pre-freeze and post-thaw periods, motility, vigor, membrane integrity, acrosome integrity, and sperm cell morphology were evaluated for each of the cryoprotectants. Post-thaw motility was higher when semen was frozen with cryoprotectants GLY and DMF (55.31 ± 7.39 and 55.94 ± 2.77, respectively), compared with the result obtained for ETG (48.13 ± 2.39). For major defects (MaD), a difference was observed between the pre- and post-cryopreservation periods, such that DMF generated a higher number of post-thaw MaD (25.94 ± 5.37). All cryoprotectants were efficient for cryopreservation of semen, resulting in samples with satisfactory viability after thawing. However, the medium with the cryoprotectants GLY, at a concentration of 6%, and DMF, at a concentration of 5%, were preferable.