Investigation of seminal plasma endogenous antioxidant capacity and its relationship with semen quality before and after cryopreservation in anatolian black bulls

In this thesis, it was aimed to determine the quality parameters of fresh and post-thaw semen, and the antioxidant concentrations in seminal plasma in bulls, as well as to evaluate the effect of antioxidants in seminal plasma on the quality of post-thaw semen, and to investigate the possibility of its use as a marker for semen freezability. For the study, 72 ejaculates were collected from 6 Anatolian Black bulls for six weeks. Collected ejaculates were separated into two aliquots. First one was centrifuged, and their seminal plasma was separated and stored at -80oC until analysis. The quality of fresh semen was evaluated with the remaining part of the semen then diluted with commercial extender, frozen in 0.25 ml straws and stored in liquid nitrogen at -196oC until analysis. Catalase, superoxide dismutase, glutathione peroxidase, total antioxidant level, total oxidant level, malondialdehyde and vitamin-E analyzes were performed in seminal plasma. After the sperms were thawed, their motility was analyzed with a CASA, and their plasma membrane and acrosome integrity (PMAI) and mitochondial membrane potential (MMP) analyzes were analyzed with a flow cytometry. In the study, mean volume, concentration, total motility and progressive motility values of fresh semen were determined as 6.37. 4,47±0,12 ml, 1264,0±44,4 *10⁶/ml, %93,4±3,77 and %45,0±6,37 respectively. Total motility, progressive motility, PMAB, and high MMP values of post-thaw semen were detected as 61.60±1.54%, 24.40±0.93%, 46.33%±1.12%, and 61.48±1.60% respectively. In addition, two-step cluster analysis was applied and semen were examined in two groups as good-freezable semen (IDS) and poor-freezable semen (ZDS) based on the post-thaw quality parameters. As a result of the analysis, PMAI and post-thaw total motility values were found significantly higher (P<0.001) in the IDS group compared to the ZDS group. While seminal plasma TAS, CAT and Vit-E values were significantly higher (P<0.05) in the IDS group, TOS and OSI values were significantly higher (P<0.01) in the ZDS group. There was no statistically significant difference between the groups in terms of SOD, GPx and MDA values. As a result, it has been observed that the seminal plasma antioxidant content is responsible for the freezability of semen, and the OSI value, which can be determined by performing TAS and TOS analyzes instead of looking for separate antioxidant enzymes, can be used as a marker for the quality of post-thaw semen at artificial insemination centers.