Changes in the Morphology and Antioxidant Status of European Red Deer Sperm Stored in the Epididymides and in a Liquid State

Simple Summary The choice of the optimal sperm preservation method is an important consideration in animal breeding. Stored semen can be used for reproductive purposes to introduce new genotypes and prevent inbreeding, which poses a considerable problem in cervid farms. The aim of this study was to evaluate and compare the effect of storage time and storage method (liquid state/epididymides) on the motility, morphology, and antioxidant status of European red deer sperm stored at 5 degrees C for up to six days (D0-D6). Sperm samples were assessed for motility, viability, morphology, activity of antioxidant enzymes (superoxide dismutase, SOD; glutathione peroxidase, GPx; catalase, CAT), and lipid peroxidation (based on malondialdehyde, MDA, content). Significant differences between storage variants were noted on D2 in sperm morphology; on D4 in the percentage of progressively motile sperm, MDA content, and SOD and GPx activity; and on D6 in the percentage of motile and viable spermatozoa. Sperm motility, viability, and antioxidant status are more effectively preserved during liquid storage than epididymal storage. Morphological and functional abnormalities of sperm were observed earlier during epididymal storage, which suggests that spermatozoa can be stored for shorter periods of time in the epididymides than in a liquid state.Abstract 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 degrees 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.