Cryopreservation of immature oocytes of the indigeneous Vietnamese Ban Pig

Abstract

We report the cryopreservation of oocytes from Ban miniature pigs which are endemic in Vietnam. Immature cumulus‐oocyte complexes were collected from antral follicles of 7–8 mo old female cyclic Ban pigs and vitrified in micro‐drops. Oocyte morphology, lipid content, post‐warming survival, nuclear maturation, and embryo development were compared to those of oocytes from commercially slaughtered Landrace × Large white hybrid pigs. The size of oocytes in the two breeds was similar. However, significantly lower amounts of intracellular lipid were detected in Ban oocytes. There was no difference (p > 0.05) between Ban and Landrace × Large white oocytes in percentages of post‐warming survival (93.1 ± 3.4% vs. 70.7 ± 16.7%, respectively) and nuclear maturation after in vitro maturation (80.4 ± 5.1% vs. 90.0 ± 1.3% respectively). Similarly, cleavage (30.8 ± 7.8% vs. 10.3 ± 6.1%, respectively) and blastocyst development rates (9.4 ± 5.0% vs. 0.79 ± 0.79, respectively) were not different (p > 0.05) between vitrified Ban and Landrace × Large white oocytes after in vitro fertilization and embryo culture. In conclusion, high survival and maturation rates were achieved after vitrification of immature Ban oocytes and their cryo‐tolerance was similar to that of Landrace × Large white oocytes, despite the difference in lipid content. We succeeded to generate reasonable rates of blastocysts from vitrified Ban oocytes by in vitro fertilization.

New Strategies for Conservation of Gentile di Puglia Sheep Breed, an Autochthonous Capital of Millennial Tradition in Southern Italy

“…Finally, there is only one study on the vitrification of immature COCs applied to local breeds. This study was performed in the Vietnamese Ban Pig, and there was no statistically significant difference in the maturation rate observed after vitrification between the Ban Pig and commercially slaughtered hybrid pigs [54]. Vitrification is known to induce oxidative stress through ROS overproduction, membrane lipid peroxidation, amino acid and nucleic acid oxidation, gene expression alteration, and mitochondrial damage, resulting in cell apoptosis [75].…”

“…Moreover, the use of this kind of ovaries allows the generation interval to be reduced, the rate of genetic gain to be increased, and more COCs to be obtained than from adult ewe ovaries [51,52]. To the best of our knowledge, there is only one study focusing on immature COC vitrification using pre-pubertal lamb ovaries [53] and only one aimed at local breed conservation in the autochthonous Vietnamese Ban Pig breed [54].…”

Optimization of in vitro embryo production and zygote vitrification for the indigenous Vietnamese Ban pig: The effects of different in vitro oocyte maturation systems

“…Embryos were cultured and the cell numbers in blastocysts were evaluated according to Somfai et al. (2019). Presumptive zygotes were cultured in 50 µl drops of PZM3 medium covered with paraffin oil in six‐well dishes (IFP9670; Research Institute for the Functional Peptides) in 5% CO 2 , 5% O 2 , and 90% N 2 at 38.5°C for 7 days.…”

“…Oocyte collection and IVM procedures were performed according to our previous report (Somfai et al., 2019). Immature oocytes were collected from a total of 33 Ban gilts at the same age (8–9 months) and body weight (19–25 kg/each).…”

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).…”