Characteristics and fertility of domestic cat epididymal spermatozoa cryopreserved with two different freezing media

The study represents a comparison of cryopreservation of domestic cat epididymal spermatozoa with two commercially available freezing media: CaniPlus Freeze (CPF) and SpermFreeze (SF). The viability of nonfrozen spermatozoa evaluated by the VitalScreen test was 68.7 ± 3.0%. These figures were lower for the frozen-thawed spermatozoa: 51.2 ± 6.3% for CPF group and 54.4 ± 3.1% for SF group. The motility of nonfrozen spermatozoa was 57.2 ± 4.5%. These figures were reduced in both frozen-thawed groups; however, there was no significant difference in these parameters between CPF (30.8 ± 7.1%) and SF (27.4 ± 8.1%) groups. The percentage of nonprogressively moving motile spermatozoa after freezing-thawing was decreased in both frozen-thawed groups (23.5 ± 5.9 and 12.0 ± 2.4 for CPF and SF frozen correspondingly) as compared with nonfrozen controls (42.1 ± 4.1%). Morphology of spermatozoa was assessed by light microscopy. The mean percentages of normal spermatozoa were 28.5 ± 4.1% for nonfrozen group, 26.0 ± 2.3% for CPF frozen group, and 23.9 ± 1.9% for SF frozen group. The most frequent anomalies in all the three groups were flagella and combined defects. In vitro fertilization (IVF) of domestic cat oocytes with nonfrozen and frozen-thawed spermatozoa produced developing embryos. The percentage of in-vitro-derived embryos was 43.6% after using nonfrozen spermatozoa. Frozen-thawed spermatozoa developed at a similar rate (44.0%) after using SF. However, the rate of embryo development was lower (20.1%) when CPF was used. The in-vitro-derived embryos in the nonfrozen group consisted of 46.9 ± 2.5 cells after 5-day culturing. After cryopreservation with SF and CPF the cell numbers per embryo were 39.9 ± 2.7 and 31.8 ± 3.4 correspondingly. In CPF group these numbers were lower than in nonfrozen controls. Cryopreservation of spermatozoa with either of two freezing media led to a decrease in post-thaw viability and motility of spermatozoa but did not affect the rate or spectrum of their morphological anomalies. The use of CPF, but not SF led to a decrease of sperm fertilizing abilities.