A Shorter Equilibration Period Improves Post-Warming Outcomes after Vitrification and in Straw Dilution of In Vitro-Produced Bovine Embryos

摘要

For more productive and sustainable livestock activity, various reproductive biotechnologies are being incorporated into breeding programs to accelerate genetic improvement. Among these strategies, embryo cryopreservation is a key technique for the conservation and dissemination of genetic resources while also optimizing animal production and biosafety. Though vitrification techniques are rapidly gaining acceptance due to their speed, simplicity, and feasibility, their practical applications in veterinary reproduction are limited because there is no standard protocol that facilitates warming in field conditions. Moreover, working time increases when a large number of embryos has to be cryopreserved. In-straw warming/dilution methods allow for the vitrification of embryos and their direct transfer to the uterus of recipients. In order to increase vitrification efficiency by reducing the working time and simplifying warming in field conditions, in vitro-derived cattle embryos at the expanded blastocyst stage were vitrified by using two different protocols (short equilibration vitrification and long equilibration vitrification) and in straw diluted/warmed. The short equilibration protocol improved vitrification outcomes in terms of embryo survival and hatching ability, and it improved embryo quality in terms of higher total cell number and lower apoptosis rate. A gene expression analysis of surviving embryos also indicated that the short equilibration treatment could lead to the production of more high-quality blastocysts.