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Published on: November 18, 2017
Effect on equine sperm of post-thaw glycerol dilution using two different semen extenders
J C Otero1, D M Neild1, A A Ferrante1
1Universidad de Buenos Aires, Facultad de Ciencias Veterinarias, INITRA, Cátedra de Teriogenología, Chorroarín 280, 1427 CABA, Buenos Aires, Argentina.
Background:
Glycerol, a penetrating cryoprotectant, is most employed for deep freezing spermatozoa. However, it can induce toxic, chemical, and osmotic effects, altering the lipid structure of the sperm membrane. Rapid glycerol addition has been demonstrated to have fewer toxic effects than its removal.
Aims/Objectives:
To minimize both the toxic and osmotic effects of glycerol on equine sperm through post-thaw dilution using two different extenders.
Methods:
Samples of equine semen frozen with 5% glycerol from nine stallions were thawed, re-diluted 1:2, and incubated for 30 minutes at 22°C in Tyrodes (Tyr) and a commercial equine extender (CE). Kinematic parameters were assessed using Computer-Assisted Semen Analysis, plasma membrane integrity and acrosome status with the fluorescein isothiocyanate-peanut agglutinin-propidium iodide stain, lipid peroxidation with the BODIPY581/591 stain, and DNA fragmentation with the Halo test.
Results:
No significant differences (P>0.05) in total (TM) and progressive (PM) motility were observed between the control (TM 43.8 ± 20.9%; PM 30.6 ± 15.2%) and the tested extenders (TM Tyr 41 ± 22%, CE 40.4 ± 19.2% and PM Tyr 27.5 ± 15.6%, CE 29.7 ± 14.4%). DNA fragmentation and lipid peroxidation also showed no significant differences (P>0.05) between treatments. However, significantly higher percentages (P<0.05) of sperm with intact plasma membranes and acrosomes were recorded in CE (39.4 ± 12.3%) compared to the control (33.9 ± 10.5%) and Tyr (33.5 ± 12.1%).
Conclusion:
post-thaw dilution did not yield beneficial effects on equine sperm parameters. However, dilution in CE potentially reduces the proportion of sperm with reacted acrosomes.
