Abstract: This study examined the effect of medium change and supplemented with fetal bovine serum(FBS), high osmolarity and the optimal concentrations of vitamin E on development of porcine embryos derived from in vitro fertilization(IVF) or parthenogenetic activation (PA), in further to improve the in vitro culture conditions of pig preimplantation embryos. Experiment 1: The medium change group of embryos were cultured in PZM-3, which was changed to fresh medium on days 2 and 4. The FBS group of embryos were cultured in the change system up to day 4 and then cultured in PZM-3 supplemented with 10% FBS instead of BSA from Day 4 to 7. Experiment 2: Sucrose group and NaCl group embryos were cultured in a modified PZM-3(300 to 320 mOsmol) with 0.05 mol/L sucrose or increased NaCl to 138 mmol/L for the first 2 days, and then cultured in PZM-3(288 mOsmol) for the next 5 days. Experiment 3: Embryos were respectively cultured in a modified PZM-3 with 50, 100, 200 μmol/L vitamin E for the whole culture period. All the control group of embryos were cultured in PZM-3 (288 mOsmol) for 7 days. In the first experiment, the FBS group showed a significantly higher rate of blastocyst compared to the control and the medium change group both of IVF embryos and PA embryos (P<0.05). In experiment 2, IVF embryos cultured in NaCl group showed a significantly higher rate of cleavage and blastocyst compared to the control and sucrose group (P<0.05). In the last experiment , IVF embryos cultured in a modified PZM-3 with 100 μmol/L vitamin E showed a significantly higher developmental rate to the blastocyst stage compared to the control (P<0.05). These results indicate that a change to fresh medium and inclusion of FBS in the medium during the late stages of culture can promote the development on both of IVF and PA embryos. The higher osmolarity (increased NaCl to 138 mmol/L) at the early embryonic stage and the supplementing porcine embryo culture medium with 100μmol/L vitamin E can promote the in vitro development of porcine IVF embryo.

Key words: medium change; FBS; osmolarity; vitamin E; pig; in vitro fertilization; parthenogenetic activation