Effects of oxidized glutathione, bovine serum albumin, cysteine and lycopene on the quality of frozen-thawed ram semen

Free radicals are known to be involved in lipid peroxidation as well as DNA and sperm membrane damages that may lead to decreased sperm motility or cell death. The balance between free radical production and their detoxification may be an important factor in sperm survival and function before, during and after cryopreservation. The aim of this study was to determine the effects of the addition of the antioxidants of oxidized glutathione (GSSG), bovine serum albumin (BSA), cysteine and lycopene to freezing media on the post-thawing sperm characteristics, including motility, morphology, acrosome integrity, viability and membrane integrity. A total number of 42 ejaculates were collected using the artificial vagina from 4 Akkaraman rams and 10 replicates of the ejaculates were diluted with a Tris-based extender containing additives and no additives as control. GSSG (5 mM), BSA (20 mg/ml), cysteine (10 mM) and lycopene (800 μg) showed more positive effects than other concentrations of the supplements and controls in protecting sperm characteristics after the freezing-thawing process (P < 0.001). Many aspects of sperm protection, e.g. sperm motility, viability and membrane stabilisation of the sperm cells during relative cryopreservation, are the key factors in determining the preservation of sperm function. The results of this study provide a new approach to the cryopreservation of sperm from rams and related breeds, and thereby contribute to the improvement of these breeds for the world sheep industry.