Protective effect of melatonin on sperm motility parameters on liquid storage of ram semen at 5°C

Abstract

Oxidative damage to sperm resulting from reactive oxygen species generated by the cellular components of semen during liquid storage is possibly one of the main causes of the decline in motility during storage. The aim of this study was to determine the effects of melatonin as an antioxidant on sperm motility parameters in liquid storage of ram semen at 5°C. A total number of 24 ejaculates were collected using the artificial vagina from four chal rams and three replicates of the ejaculates were diluted with a Tris-based extender with melatonin at the doses of 0.1, 1 and 3 mM and an extender containing no melatonin (control). Diluted semen samples were cooled from 37 to 5°C. A computerassisted sperm motility analysis was used to analyze sperm motion characteristics. The sperm motility parameters such as progressive motility, straight linear velocity (VSL), curvilinear velocity (VCL), average path velocity (VAP), head displacement (ALH), sperm track straightness, (STR) and linearity (LIN) were determined in the storage of semen at 5°C for a period of 48 h. The extender supplemented with 1 mM melatonin led to higher percentages of progressive motility and LIN (46.4 and 58.9, respectively) and higher value of VSL and VAP (78.4 and 91.1 µm/s, respectively) in comparison to the control (P 0.05) effect in ALH and STR of the whole semen compared to the control sample. The results indicated that supplementation of melatonin to the semen extender can improve the semen motility.