The Protective Effect of Antioxidants on Liquid and Frozen Stored Ram Semen – Review

This systematic review is focusing on the current literature in order to give an overview of the protective role of antioxidants in ram semen preservation. Throughout the sperm conservation process the unsaturated fatty acids of the spermatozoa membrane binds oxygen and evolves numerous peroxide bonds. The lipid peroxidation leads to unbalanced oxidative stress that causes different impairments of sperm cells, and acrosome loss. ,,Cold shock” also induces caspase cascade involved in apoptosis, DNA fragmentation and in overall it has a detrimental effect on the fertilizing capacity of spermatozoa. Nowadays the cryopreservation of semen is considered as a routine procedure in cattle. Despite the various advantages of the method, the recovery rate of live and intact spermatozoa still remains low in boar, dog and ram samples. Previously several studies highlighted that the addition of antioxidants could improve the survival and motility rates, because antioxidants acted as free radical scavengers and protected spermatozoa against reactive oxygen species (ROS). Enzymatic antioxidants as superoxide dismutase (SOD), catalase, glutathione peroxidase (GPX) and non-enzymatic antioxidant molecules like tocopherol, ascorbic acid, pyruvate, resveratrol have a protective effect against membrane damage that occurs during semen preservation process.