Effect of progesterone supplementation of maturation medium on the development of IVM-IVF-IVC bovine embryos

The objective of this study was to investigate whether progesterone (P_4) supplementation to in vitro-maturation (IVM) medium could affect the competence of bovine oocyte to develop into blastocysts in vitro. Cumulus—oocyte complexes (COCs) were collected by aspiration of ovarian follicles (2 to 6 mm in diameter) obtained from a local abattoir. The COCs were matured for 20 h in TCM-199 supplemented with 5% calf serum (CS) and 0.02 AU mL^ FSH, at 38.5℃ in an atmosphere of 5% CO_2 in air. P_4 was added to the IVM medium at 10 h after the start of the culture (1 μg mL^ of P_4: 1 μg group; 5 μg mL^ of P_4: 5 μg group; without P_4: control group). The matured COCs were inseminated with 5 x 10^6 sperms mL^. After 18 h of gamete co-culture, the presumptive zygotes were cultured in CRlaa containing 5% CS at 38.5℃ in an atmosphere of 5% CO_2, 5% 0_2 and 90% N_2 for 9 days (fertilization, day 0). The rates of MII, cleavage and blastocyst formation were analyzed by the chi-square test. Each set of cell numbers (mean ± SE) was analyzed by the unpaired t-test. The MII rate in the control group was significantly lower (P < 0.05) than that in the 1 μg group. The cleavage rate in the 1 μg group was significantly higher (P < 0.05) than those in the control group and 5 μg group. Further, the blastocyst formation rate in the 1 μg group and 5 μg group were significantly higher (P < 0.05) than that in the control group. However, there was no significant difference in cell numbers among the groups. In conclusion, timely P_4 supplementation in IVM medium give rise to high developing rates in bovine embryo cultured in vitro.酪農学園大