Investigation of cryoprotective effects of different selenium forms on freezing of dog sperm: Comparison of nanoparticle selenium and sodium selenite

This thesis aimed to investigate the protective effects of nanoparticle selenium (SeNP) and sodium selenite (SS) on preventing oxidative stress during the freezing process of dog semen. A total of six dogs were used in the study. The ejaculate was collected from dogs three times at different times by massage method. A total of 18 ejaculates were used and each ejaculate was divided in five experimental groups. The experimental groups were designed to tris extender containing no antioxidants control, 1 µg/ml (SeNP1), 2 µg/ml (SeNP2) nanoparticle selenium, and 1 µg/ml (SS1), 2 µg/ml (SS2) sodium selenite. Extended semen samples were equilibrated for 1 h at 4 °C then frozen in liquid nitrogen vapour and stored in liquid nitrogen (~-196°C). After thawing, semen samples were evaluated in terms of CASA motility and kinematic parameters, spermatozoa plasma membrane integrity and viability (HE Test), spermatozoa morphology (SpermBlue), DNA fragmentation (GoldCyto) and antioxidant profile. When the results were evaluated statistically, the progressive motility, VCL, and VAP kinematic parameters in the SeNP1 group were significantly higher than the control group after thawing (P<0.05). The highest ratio of plasma membrane integrity and viable spermatozoa was observed in the SeNP1 group,but there was no statistical difference was found between the groups (P>0.05). Although the ratio of total morphological disorder was observed to be lower in all groups to which different selenium forms were added, compared to the control group, no statistical difference was found. Spermatozoa tail abnormality was significantly lower in the SeNP1 group than in the control and SS2 group (P<0.05). The lowest ratio of fragmented DNA was observed in the SeNP1 group,but there was no statistical difference was found between the groups (P>0.05). Although there was no statistical difference between the groups in the evaluation of sperm antioxidant profile, the highest GPX, SOD and CAT values and the lowest lipid peroxidation values were obtained in the SeNP1 group. As a result, it was determined that 1 μg/ml dose of SeNP added to the tris-based extender in dog semen was beneficial on spermatological parameters and nanoparticle selenium, which is a nanotechnology product, contributed significantly to the freezing of dog semen. Keywords: Cryopreservation, Dog, Nanoparticle Selenium, Semen, Sodium Selenite