STUDY OF FROZEN PIG EMBRYOS AND ITS TRANS PLANTATION

Pig embryos seem to be extremely sensitive to cooling or freezing as w ith other animals. Although a technique for freezing pig embryos has b een developed quite recently, our project compared the survival rate o f the concentration of a cryoprotective agent (glycerol) : different f reezing media, and different stages of pig embryos. We then tried to t ransfer surviving frozen pig embryos to recipients. Donors and recipie nts were obtained from gilts 7-8 months of age, and mated or artificia lly inseminated during second estrus cycle. Embryos were collected 6 d ays after mating or artificial insemination by surgical operation. Bla stocyst to hatched blastocyst pig embryos were frozen to -196-degrees- C : after freezing and thawing pig embryos were incubated in 37-degree s-C, 5% CO2 or transferred to recipients. The results were : 1 . PBS- containing 50% fetal calf serum (FCS), 15% egg yolk, 0.4% bovine serum albumin (BSA), and 1.5M glycerol had better survival rate than PBS co ntaining 20% FCS and 1.5M glycerol used as the freezing solution for p ig embryos. 2 . Concentration of 1.5M glycerol had better survival rat e than concentration 1.0M glycerol used as the cryoprotective agent fo r freezing pig embryos. 3 . As to freezing and thawing pig embryos fol lowed by in vitro culture, the survival rates of blastocyst, expanded blastocyst, hatching blastocyst and hatched blastocyst were 0, 53, 38. 5, and 73.2%, respectively. 4 . As to survival of frozen pig embryos f ollowed by in vitro culture transferred to 9 recipients, on day 117, o ne of the recipients was born one piglet (death) and 5 piglets (includ ing 2 dead and 3 live) transferred from frozen (Yorkshire X Duroc) and fresh (Duroc x Duroc) pig embryos, respectively. The experiment indic ated frozen pig embryo's at the stage of expand blastocyst to hatched blastocyst had higher survival rate after in vitro culture, but there were extremely low farrowing rates when transferred to recipients.