Canine epididymal sperm vitrification with egg yolk and coconut water extender

The aim of this study was to assess the efficiency of coconut water extender with addition of 20% egg yolk (CWE+EY) for canine epididymal sperm vitrification. Twenty epididymides were removed from ten adult dogs. Sperm samples were retrieved in Petri dishes by the float-up method on a heating stage (37.0 °C). The epididymides and proximal ductus deferentes were incised and suspended in 6 mL coconut water extender with addition of 1% fructose. After 45 min, the samples were collected and sperm quality parameters (viability, motility, morphology) were assayed using a computer-aided sperm analysis (CASA) system. After centrifugation, the supernatant of each sample was removed and the semen pellets were resuspended in the same extender with added egg yolk. Equilibration was performed at 5 ºC for 60 minutes, semen was vitrified by direct dropping into liquid nitrogen in spheres with a volume of 30 μL. After a week of storage in cryotubes, spheres were devitrified as three of them were dropped into 0.5 mL of CaniPlus AI (Minitüb, Germany) at 37 ºC for 2 minutes and the same parameters were reevaluated. Vitrification resulted in significantly (P0.05) in relation to pre-freezing samples. Our results demonstrated that vitrification with CWE+EY extender as cryoprotectant had excellent potential for canine male gamete preservation.