Thawing dog spermatozoa in just-boiled water: submersion time and effect on sperm quality compared to thawing in water at 70 degrees C.
Dog spermatozoa have better quality after thawing in water at 70-75 degrees C instead of 35-38 degrees C. The aim of Experiment 1 was to determine the time needed to thaw 0.5 mL straws in just-boiled (98 degrees C) water and that of Experiment 2 to determine whether thawing frozen dog spermatozoa in just-boiled water will result in better quality than thawing in water at 70 degrees C. Prior to freezing the straws of Experiment 1, a Type J thermocouple with wire diameters of 0.08 mm (Osiris Technical Systems, Centurion, South Africa) was placed in the center of each of ninety-three 0.5 mL straws (IMV Technologies, L'Aigle, France) filled with extender (Biladyl* with 0.5%, v/v of Equex STM paste**) and 54 filled with extender plus 200 x 10(6)spermatozoa/mL (Minitüb, Germany (*) and Nova Chemical Sales, MA (**)). Thirty straws with extender were thawed in water at 70 degrees C and the others in just-boiled water. Temperatures inside straws were recorded 10 times/s during warming. Two ejaculates were then collected from each of eight dogs and one from each of three others. Extended ejaculates from the same dog were pooled, frozen 8 cm above liquid nitrogen, and 2 straws from each of the 11 batches thawed in water at 70 degrees C for 8s and 2 in just-boiled water for 6.5s. Sperm morphology and viability were assessed on eosin-nigrosin smears made after thawing and the percentage progressively motile spermatozoa was estimated immediately, 1, 2 and 3h after thawing. The optimal submersion time in just-boiled water was 6.5s for both sperm concentrations, resulting in average temperatures of 23.6+/-1.5 degrees C (+/-S.E.M.) and 24.9+/-1.6 degrees C inside straws with extender or extender plus spermatozoa (P=0.6). The temperature inside straws thawed in water at 70 degrees C was 13.6+/-1.7 degrees C after 8s. Apart from a 1.5% higher (P<0.05) mean percentage motile sperm 2h after thawing, thawing dog spermatozoa in just-boiled (98 degrees C) water holds no benefit over thawing in water at 70 degrees C, which is easier to do.
Nöthling
J O
JO
Section of Reproduction, Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, South Africa. johan.nothling@up.ac.za
Dolieslager
S M J
SM
Fillekes
R
R
Colenbrander
B
B
D000177:Acrosome / Q000502:physiology; D000818:Animals; D002470:Cell Survival / Q000502:physiology; D015925:Cryopreservation / Q000379:methods / Q000662:veterinary*; D004285:Dogs / Q000502:physiology*; D008297:Male; D011897:Random Allocation; D012662:Semen Preservation / Q000379:methods / Q000662:veterinary*; D013081:Sperm Motility / Q000502:physiology; D013094:Spermatozoa / Q000502:physiology*; D013696:Temperature