Effects of the 7 21 Robertsonian translocation on fertilization rates and preimplantation development of bovine oocytes in vitro

A study was conducted to investigate the effect of the 7/21 Robertsonian translocation on fertilization and subsequent development of bovine oocytes matured in vitro. Semen from Japanese Black bulls, 2 with a normal karyotype (Bulls A and B) and 2 that were heterozygous for the 7/21 translocation (Bulls C and D), was used in this study. In vitro matured bovine oocytes were inseminated with frozen-thawed sperm capacitated with heparin. After insemination, oocytes were cultured at 38.5 degrees C on a monolayer of cumulus cells in TCM-199 supplemented with 5% superovulated cow serum and 0.5 mM sodium pyruvate in an atmosphere of 2% CO2 in air. Cleavage rate was evaluated at 54 h after insemination, and development of embryos to the blastocyst stage was observed 7 to 10 d post insemination. There was no difference in the fertilization rate among the 4 bulls. Although the cleavage rate of oocytes inseminated with semen from Bull C (heterozygote) was lower (P < 0.05) than that obtained with semen from Bull B (normal), the blastocyst formation rate did not differ among the 4 bulls. These results indicate that the 7/21 Robertsonian translocation had no effect on the fertilization and blastocyst formation rates of bovine in vitro-matured oocytes.