Avaliação de diferentes diluentes na criopreservação de sêmen ovino (Ovis aries)

Abstract

During cryopreservation are numerous changes experienced by the sperm cells, which leads to the decrease in motility and loss of viability after thawing. For this reason, there arises the need to refine the process technology of semen, especially regarding the use of diluents. The aim of this study was to evaluate the viability of spermatozoa undergoing the process of cryopreservation and dilution, using three extenders (TES, TRIS and PBS) and three years of stability (4h, 8h and 12h), and the study was divided into nine groups: TES-4h-8h TES, TES- 12h, TRIS-4h-8h TRIS, TRIS-12h-4h PBS, PBS and PBS-8h-12h. After collection, semen was evaluated macro and microscopically, and pre-diluted solutions in TES, TRIS and PBS, but without the addition of cryoprotectants (Solution A), where they remained for 1 hour. Subsequently, semen was diluted with solutions TES, TRIS and PBS, already containing the cryoprotectants, again assessed to be so packed, and subjected to different periods of equilibrium, and then frozen. After thawing, motility was assessed and vigor, and after the TTR, motility, vigor and detachment of the acrosome. On cryopreservation with TRIS, motility and vigor were statistically similar (p> 0.05) in semen frozen with a balance of 4h (17.2% and 1.6), 8h (22.4% and 2.1) and 12h (14.8% and 1.6) (p> 0.05). After the TTR was not observed statistical difference (p> 0.05) in motility and vigor in 4h (10.4% and 1.1) and 12h (10.0% and 1.2) of balance, but there was an increase in 8h (15.6% and 1.6) (p <0.05). There was no statistical difference (p> 0.05) in the rate of detachment of the acrosome between 4h (35.1) and 12 (37.6) equilibrium, with a reduction in these indices at 8 am (30.4) (p <0 , 2005). On cryopreservation with ERT, the motility of frozen semen with a balance of 4h (24.8%) and 12h (27.6%) were statistically similar (p> 0.05), although the time of 8h (40.4% ) differed significantly from the others. The force was statistically similar (p> 0.05) for thawed-balanced 4h (2.0), 8h (2.6) and 12h (2.3), not statistically different (p> 0.05) . After the TTR was not observed statistical difference (p> 0.05) for sperm motility in 4h (18.8%) and 12h (17.4%) of balance, but there was an increase in 8h (29.6%) (p <0.05). In relation to the force and the detachment of the acrosome was no statistical difference (p> 0.05) 4h (2.0 and 35.8), 8h (2.1 and 33.4) and 12h (1.8 and 42 , 2) equilibrium. On cryopreservation with PBS, showed no motility and vigor after thawing. These results indicate that solvent-based TES and the equilibrium time of 8h were more suitable for dilution and freezing of ram semen.