Variación de los efectos de la melatonina sobre la motilidad y funcionalidad del semen ovino refrigerado

Abstract

Melatonin is a potent indolaminic antioxidant that protects cell membrane integrity against oxidative stress and stabilizes mitochondrial functionality. To determine the functional dose of melatonin on chilled ram semen based on the variation of its effect on motility and sperm functionality was the objective of this study, evaluating various concentrations on Katahdin and Blackbelly ram semen at 5 °C. A logarithmic scale from 1/16 mM to 16 mM was used, with 8 replicates during 2, 4, and 24 hours. Results demonstrated that melatonin acts in a dose-dependent manner under a second-grade polynomial model as a function of log₂, reaching its maximum biological efficacy at 4 hours. During this period, optimal values were recorded for vitality (80%) with 1.46 mM, progressivity (40.20%) with doses near 16 mM, and linearity (38.06%) with 0.5 mM. The parabolic behavior of linearity warns of a biphasic effect, where excessive concentrations are counterproductive for cellular kinematics. It is concluded that a concentration of 1.5 mM represents the optimal balance to preserve the structure and displacement capacity of the ovine sperm in these breeds, being the suggested dose for subsequent cryopreservation.

Keywords: Melatonin, cryopreservation, linearity, vitality, progressiveness