Comparison of acetamide and dimethylsulfoxide as cryoprotectants of European brown hare (Lepus europaeus) spermatozoa.

The aim of the present study was to assess the effect of dimethylsulfoxide (DMSO) and acetamide on the post-thaw properties of hare semen and to perform an AI trial with frozen-thawed semen. Semen was collected under general anaesthesia by the electroejaculation method from 6 males. Immediately after collection, the semen was diluted with an extender containing the following components: 250 mM Tris, 80 mM citric acid, 70 mM glucose, 1.0 M DMSO, egg yolk (17% v/v) and kanamycin (80 mg/l); this extender was used for Protocol I (n=17). In Protocol II (n=15), the DMSO was replaced with 1.0 M acetamide. Immediately after thawing and after incubation for 90 and 180 min at 37 C, the properties of semen were evaluated by computer-assisted semen analysis, and the percentage of viable, acrosome intact spermatozoa was evaluated using flow cytometry. During the 3-h incubation, the percentages of motile spermatozoa and spermatozoa with progressive motility were significantly higher in Protocol I (P<0.01). Immediately after thawing, path and straight velocity were significantly higher in Protocol I (P<0.01), as was the curvilinear velocity (P<0.05). The amplitude of lateral head displacement was higher after 3-h incubation in Protocol I (P<0.05), and no differences in beat cross frequency were found between Protocol I and II at any incubation time. The percentage of viable, acrosome intact spermatozoa determined with flow cytometry was higher in Protocol I (P<0.01) at all incubation times. As a result of artificial insemination with the semen frozen with DMSO as a cryoprotectant, two out of three inseminated females delivered two healthy young each. Following artificial insemination with the semen frozen with acetamide as a cryoprotectant, two out of three inseminated females delivered one healthy young each. On the basis of the results, it should be stated that DMSO ensures better post-thaw properties of hare spermatozoa than acetamide.