Antioxidative/ oxidative balance of semen during preservation

The use of artificial insemination (A.I.) in domestic animals has significantly increased in recent years. The advantages of A.I. are the prevention of sexually transmitted diseases, the control of semen quality and the possibility for transportation of cooled and frozen semen. The success of AI does, however, not only depend on fertility and state of female animal but also on the fertilizing capacity of semen after storage. Semen preservation is a complex process, requiring the determination of the best conditions in order to maintain the quality and fertilizing potential of semen. Cooling and freezinghawing of semen induce the formation of reactive oxygen species (ROS) and there is evidence from humans that ROS are involved in spermatozoal membrane damage. This damage results in a loss of sperm motility and thus a decreased fertility of A.I.The level of ROS production is controlled by antioxidative defence systems in semen and can be described by determination of products from the peroxidative processes of macromolecules. The aims of the proposed study are to describe the antioxidative/oxidative status of stallion ejaculates, to compare the activity of antioxidative defence systems and the level of peroxidative processes during cooling and freezinghawing of semen and to decrease the ROS production in semen by adding antioxidants (ascorbic acid, superoxide dismutase) to semen during processing. The activity of enzymatic and non-enzymatic antioxidative defence systems as well as the level of lipid, protein and nucleic acid peroxidation products in the whole ejaculate, spermatozoa and seminal plasma of stallion semen will be determined spectrophotometrically, spectrofluorimetrically and by HPLC. Semen quality will be determined by computer-assisted motion analysis and transmigration and by analysis of membrane integrity with fluorescent stains. The results will help to explain the role of antioxidative/oxidative balances for semen preservation and will help to improve semen preservation techniques for successful AI.