The aim of this study was to evaluate the motility, morphology, and antioxidant status of European red deer sperm stored in a liquid state (variant I) and in the epididymides (variant II). Spermatozoa were harvested post-mortem from the cauda epididymis. Sperm samples in both variants were stored for up to six days (D6) at 5 °C. Spermatozoa were assessed for motility, viability, morphology, activity of antioxidant enzymes (superoxide dismutase, SOD; glutathione peroxidase, GPx; catalase, CAT), and lipid peroxidation (malondialdehyde, MDA, content). Sperm samples were analyzed on storage days 0, 2, 4, and 6 (D0-D6). Storage time and storage method significantly (p ≤ 0.05) influenced the examined variables. On D2, a decrease in motility and acrosomal integrity was observed in both storage variants, whereas a decrease in viability and an increase in MDA content were noted in spermatozoa stored in the epididymides. On D4, higher values of SOD and GPx activity and MDA content were noted in variant I than in variant II. Catalase activity was very low. GPx is the key enzyme that participates in the reduction of hydrogen peroxide in sperm cells. Spermatozoa stored in a liquid state were characterized by higher motility and viability, improved morphology and antioxidant status than those stored in the epididymides; therefore, liquid storage is more recommended for short-term preservation of epididymal spermatozoa.

The biological properties of European red deer (Cervus elaphus elaphus) spermatozoa stored in the epididymides and in a liquid state were compared. Spermatozoa were collected from the epididymides harvested post-mortem. In the first variant, spermatozoa were diluted in two extenders (Bovidyl® and Salomon\'s), and were stored at 5 °C for up to 144 h. In the second variant, spermatozoa were stored in the epididymides at 5 °C for up to 144 h, and then diluted in the same extenders. Biological properties were evaluated after 0, 48, 96, and 144 h of storage. Sperm motility parameters were determined in the CASA system. Plasma and acrosomal membrane integrity, mitochondrial activity, apoptotic changes, and DNA integrity were assessed by the fluorescence method. Most variables were significantly influenced by the storage method and time. At 144 h, differences (P ≤ 0.05) in sperm parameters were observed between storage variants. Total motility (TMOT), plasma membrane integrity, and mitochondrial activity decreased below 50% of baseline values in the spermatozoa stored in the epididymides, but remained above 70% of baseline values in the spermatozoa stored in a liquid state. The compared storage variants did not differ in TMOT, mitochondrial activity, or the percentage of viable spermatozoa without apoptotic-like changes up to 96 h of storage, regardless of the applied extender. The earliest significant changes were noted in sperm motility parameters. In conclusion, European red deer spermatozoa can be stored in the epididymides at 5 °C for up to 96 h, but their biological parameters are more effectively preserved during liquid storage.

The aim of the study was to evaluate viability longevity and quality of liquid-stored epididymal sperm of European red deer (Cervus elaphus elaphus). Sperm samples were recovered from epididymides of 15 mature stags. Samples were diluted to 100 × 106 sperm⁄mL in modified Salomon\'s extender and stored at 5 °C for 25 days. Sperm were analyzed to determine total motility (TMOT), progressive motility (PMOT) and motion variables [CASA system], acrosomes with normal apical ridges (NAR), viability and acrosomal status (FITC-PNA/PI), plasma membrane integrity (PMI) and mitochondrial membrane potential (MMP) on the first day (D1) and every other day of storage (D3-D25). Data were analyzed using a one-way analysis of variance (ANOVA). Spermatozoa remained motile until D25, whereas TMOT exceeded 60%, NAR and PMI exceeded 80%, FITC-PNA/PI exceeded 75%, and MMP approximated 70% until D11. There was a lesser (P < 0.05) value for these variables on D5 (relative to D1). Furthermore, there was a decrease in values for motility variables as duration of storage increased, excluding amplitude of lateral head displacement, on D3. The results indicate that liquid-stored epididymal sperm of European red deer are characterized as having a long viability (25 days) with a retention of sperm quality for as long as 11 days in the liquid storage state. In vitro or in vivo studies, however, are required to confirm the findings in the present study.