Three protocols for the open pulled straw (OPS) vitrification of ovine GV-oocytes with slow cooling-rapid thawing, rapid cooling-slow thawing, and rapid cooling-rapid thawing were tested. The effect of ultra-rapid cooling in liquid nitrogen slush and superfine open pulled straws (SOPS) was also studied. Our results prove that both rapid cooling and rapid thawing are contributing in improved results achieved with the OPS technology. The use of liquid nitrogen slush is beneficial for ovine GV stage oocyte nitrification.