Introduction The addition of low-molecular-weight antioxidants during the freezing process improves post-thaw sperm quality. The high antioxidant potential of cryopreserved semen could have a positive effect on the motility, viability, and energy status of sperm cells and their ability to bind to the zona pellucida of oocytes. The aim of the study was to determine the effects of different concentrations and combinations of vitamins E and C in a semen extender on selected quality parameters of frozen-thawed canine spermatozoa. Material and Methods The experimental material was the semen of four mixed-breed dogs. Sperm viability (motility, plasma membrane integrity, and mitochondrial function) was examined at 0, 60, and 120 min in semen samples supplemented with the extender and in the controls. Results Combined supplementation with vitamins C + E at a concentration of 200 + 200 μM /1 × 10⁹ spermatozoa had the most profound effect on total sperm motility, linear motility, and the percentage of spermatozoa with intact plasma membrane and active mitochondria. Conclusion The synergistic activity of vitamins E and C had a more beneficial influence on the quality of frozen–thawed sperm than these non-enzymatic antioxidants applied separately.

The aim of this study was to determine the effect of two variants of Tris-citric acid-fructose (TCF) extender containing whole hen egg yolk (TCF-HEY) and lyophilized lipoprotein fractions extracted from ostrich egg yolk (TCF-LPF_o) on selected biological properties of cryopreserved sperm cells. Post-thaw percentage of motile sperm (MOT) was significantly higher (P<0.05) for TCF-HEY extender (66.3 ± 3.2%) than for TCF-LPF_o extender (52.4 ± 3.4%). Moreover, there was no significant difference in the percentage of sperm with progressive motility (PMOT). Both diluents effectively preserved sperm plasma membrane integrity and mitochondrial function. However, it was observed that cryopreservation impaired the functionality of antioxidant sperm enzymes. The above was manifested by reduced SOD activity, in particular in samples preserved in the TCF-HEY extender, as well as decreased GPx activity. Both diluents inhibited the rate of lipid peroxidation in sperm plasma membrane during freezing-thawing. Our results suggest that LPF_o is a satisfactory alternative to hen egg yolk in the extender used for canine sperm cryopreservation.