Vitrification of in vitro matured oocytes of Mangalica and Large White pigs

Abstract

The breeding of Mangalica, a native pig breed in Hungary, had been started in 1833, but this pig breed almost became extinct in Hungary in the past decades. In 1991, the number of sows was only 200. Although in these days the existing Mangalica population consists of more than 6000 animals representing different colour variations, the preservation of this traditional pig breed is still very important. Vitrification is a potential tool for the preservation of gametes and embryos of these animals. The aim of this study was to investigate the effects of vitrification on the developmental competence of Mangalica (M) and Large White (LW) oocytes following fertilisation. The oocytes were vitrified by the Open Pulled Straw (OPS) method using different concentrations of ethylene glycol and dimethyl sulphoxide as cryoprotectants. After rehydration the oocytes underwent in vitro fertilisation; the resultant zygotes were then cultured in vitro for four days to assess embryonic development. In the first experiment, in vitro maturation of M and LW oocytes was compared. No significant difference was observed in the nuclear maturation rate of LW and M oocytes. In the second experiment, the sensitivity of oocytes to vitrification was examined by evaluating oocyte morphology after thawing. A higher percentage of LW oocytes showed normal morphology compared to M oocytes, indicating that Mangalica oocytes are more sensitive to cryoprotectants than Large White oocytes. After warming and in vitro fertilisation, more than 50% of the oocytes started embryonic development and by the end of the incubation period morula stage embryos had developed in both groups. The results show that the OPS vitrification technique is well suited to preserve Mangalica oocytes and from these oocytes morula embryos can be produced.

Factors Affecting Cryopreservation of Porcine Oocytes

“…However, despite of high survival rates, vitrified M-II stage oocytes generally show poor developmental competence in terms of blastocyst formation rates and cell numbers in blastocysts [18]. Furthermore, most studies describing blastocyst production from vitrified porcine M-II stage oocytes used parthenogenetic activation to generate embryos [23, 28,[37][38][39], whereas other studies using IVF often reported the failure of embryo development [21,[40][41][42][43]. Similarly, in our laboratory, we have succeeded in the generation of blastocysts from vitrified M-II stage oocytes by parthenogenetic activation [25], whereas IVF of the M-II stage oocytes vitrified by the same method did not result in blastocyst development [27].…”

Innovations in cryoconservation of animal genetic resources

“…Various protocols for the vitrification of porcine oocytes and embryos have been reported, and the development of a standardized (optimum) protocol would be beneficial for each. To date, oocyte cryopreservation for gene banking has only been reported in two local breeds (Varga et al, 2008;Somfai et al, 2019).…”

Production of Agu piglets after transfer of embryos produced in vitro

“…If piglet production using an IVP system could be available for indigenous breeds, it would be advantageous for the preservation of genetic resources or breeding activities. Although, to our knowledge, this has not yet been reported, IVP has been established for some indigenous pig breeds (Nguyen et al, 2015;Varga et al, 2008),…”