Studies on cryostorage of canine semen with special reference to methods of cold damage evaluation

The aim of the thesis was the evaluation of the effect of a non commercial lecithin-based extender on functional integrity of canine ejaculated spermatozoa stored at +5°C for 4 days or frozen in liquid nitrogen. The results showed that soybean lecithin is a valid alternative to egg yolk for chilling and freezing canine semen, as similar rates of motility, number of uncapacitated spermatozoa and spermatozoa bound to the oocyte zona pellucida were obtained in semen chilled or frozen with the two different extenders. However, the development of purification protocols to improve the quality of fresh semen samples before cryopreservation could contribute to increase thawed semen quality and the success rates of assisted reproductive techniques. The treatment of fresh canine semen with Pisum Sativum Agglutinin beads, which bind sperm with altered acrosomes, did not result in a significant improvement of fresh or thawed semen quality, although an increase of proportions of spermatozoa with intact acrosomes was observed after purification and was maintained after thawing.