DefinePK

Abstract

Technologies in the field of oocyte and embryo cryopreservation are important tools for reproductive biotechnology, animal production, genetic preservation, and assisted reproduction. In this study, slow-freezing, standard vitrification, and modified vitrification supplemented with antioxidants and non-permeating cryoprotectants were compared for bovine, ovine, and equine species. One hundred and eighty oocytes and 120 embryos of each species were preserved, and the efficiency of post-thaw survival, fertilization rate, cleavage rate, blastocyst formation, and pregnancy based on embryo transfer were evaluated. Modified vitrification consistently yielded better results than slow-freezing and standard vitrification. Post-thaw survival increased by 15–20% with modified vitrification, and fertilization and cleavage rates were significantly higher, especially in bovine. The pattern of blastocyst formation and pregnancy rates was also similar, with bovine embryos being the most cryotolerant and equine embryos appearing to be the least cryotolerant. The effects of species and cryopreservation methods were highly significant for all assessed parameters (p < 0.05). These results further underscore the potential of optimizing vitrification methods to enhance reproductive efficiency and species conservation in the field of veterinary theriogenology. However, interspecies differences, cryoprotectant toxicity, and potential molecular changes remain challenges that need to be further investigated. This study highlights the possibilities and limitations of cryopreservation and indicates that the development of species-specific modifications to cryopreservation is indispensable for wider and more stable applications in domesticated or endangered animals.