Turkish Journal of Veterinary & Animal Sciences




Cat semen was extended with 3% and 4% glycerol containing Tris extender and frozen in (0.25 ml) straws. Spermatological characteristics were examined in post-thaw semen samples. Five tom cats aged 2-3 were used. Semen was collected by electro-ejaculator under general anesthesia (xylazine-ketamine HCl combination). On a weekly basis a total of 8 ejaculates were collected from each tom cat. Spermatozoon concentration (x10^6/ml) was determined by the hemocytometric method. Morphologic examination was done by light microscope with Spermac® stain (x1000 magnification, immersion objective) and progressive motility was examined by hot-plate phase-contrast microscope (x200 magnification). Semen samples chosen as suitable for being frozen were extended 1:1 (semen/extender) by Tris extender containing 20% egg yolk without glycerol [Tris (hydroxymethyl-aminomethane) (2.40 g) - fructose (1.00 g) - citric acid (1.30 g) osmolarity: 285 mOsmol/kg] at +26 ºC. Extended semen was cooled to +5 ºC in 1 h and divided into 2 parts. Each volume was re-extended with glycerol containing Tris extender to obtain 3% and 4% final glycerol levels. The semen samples were left under equilibration for 30 min after glycerolization. Semen was filled into 0.25 ml straws and frozen in liquid nitrogen vapor. Frozen semen samples were stored in liquid nitrogen at -196 ºC. The application was repeated 8 times for the tom cats and 40 straws were frozen for each group (n=40). The frozen straws were thawed for 30 s at 37 ºC. During the study, examinations of motility (%) and morphology (%) (acrosome, other and total) were done at collection, dilution at +26 ºC, chilling at +5 ºC, equilibration and post-thaw points. The mean post-thaw motility, acrosome, other and total morphologic defect rates with 3% glycerol containing Tris extender were 53.00 ± 10.85%, 26.35 ± 8.55%, 14.43 ± 3.99% and 40.53 ± 11.00%, respectively. These values were 50.50 ± 13.90%, 25.45 ± 7.08%, 15.20 ± 4.36% and 40.40 ± 10.22%, respectively, with 4% glycerol containing Tris extender. The differences between the values of the 2 groups were not statistically significant (P > 0.05). At the end of the study, it was observed that 3% and 4% glycerol containing Tris extender could be used to preserve the post-thaw motility and morphology of cat semen frozen in straws.

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