Transfer of vitrified embryos of pigs

Currently, embryo cryopreservation is a commonly used technique of embryo transfer in the main species of farm animals. Trials with embryo cryopreservation in pigs have not been successful before now. Nagashima et al. (1994) presented a survey reporting on the birth of 14 piglets in total in various trials. Cryopreservation of pig embryos have been very difficult. The method of vitrification - method of mammalian embryo cryopreservation without ice crystals being formed - seems to be convenient for cryopreservation of mammalian embryos. About five days old embryos in the stage of perihatching blastocysts were used for preservation. The preserved embryos were used for laparoscopic transfer to three recipients that received 13, 15 and 15 thawn embryos, respectively. The transfer was not successful; the recipients returned to estrus in 22, 22 and 23 days, respectively. It is therefore difficult to say whether the case was embryonic mortality in the last recipient. Group 2 comprised five recipients in total (2 uninseminated and 3 inseminated ones). Following the transfer of 13 to 16 embryos, conception was observed in one uninseminated recipient (abortion at the end of the 2nd month of gravidity) and one inseminated recipient. Both recipients became pregnant after embryo transfer by vitrification technique described in the paper by Riha (1993). The inseminated pregnant recipient delivered seven piglets, six of them were live-born; three piglets are phenotypically different, born from cryopreserved embryos. This trial enabled us to be among a few stations where cryopreservation of porcine embryos has been successful.