Sviluppo di un sistema definito per la crioconservazione del seme di becco di razza sarda

This study aimed at developing a chemically defined extender for goat semen cryopreservation, by testing different molecules as a substitute to egg yolk: trehalose, a non-permeable cryoprotectants; melatonin, a potent antioxidant; cholesterol, a cell membrane stabilizer; and lecithin, a source of low density lipoprotein. Semen was obtained from 5 adult bucks by artificial vagina, pooled and cryopreserved. Both before and after thawing, semen viability, percentages of progressive motile and rapid spermatozoa, and ATP intracellular content were evaluated. After thawing, antioxidant defenses (total thiols, GSH, total antioxidant capacity) were assessed. Trehalose cryoprotective effects was evidenced when added at 4°C before the freezing procedure using a concentration of 50mM. Melatonin at the tested concentrations was not effective in enhancing buck spermatozoa cryotolerance. The most effective concentrations of cholesterol (4.5 mg/mL) and lecithin 1% (w/v) proved to exert their beneficial effects during semen cryopreservation also in association with trehalose. Finally, we compared spermatozoa quality, DNA integrity, and in vitro fertilizing capacity, after cryopreservation in a cholesterol and lecithin based extenders, with and without trehalose supplementation, in a egg-yolk based and a commercial extenders. Lecithin alone can be used as a substitute for egg yolk, considering the higher motility, and fertilization rates obtained when compared to the other tested media.