Production of Japanese Black calves by the transfer of embryos developed from in vitro-fertilized oocytes derived by ovum pick up and matured in culture with the mitogen-activated protein kinase kinase inhibitor U0126

This study investigated whether treatment with the mitogen-activated protein kinase kinase inhibitor U0126 during in vitro maturation (IVM), which has previously been reported to improve oocyte developmental competence, is practical for use in calf production using ovum pick up (OPU)-derived oocytes. Two Japanese Black cows were repeatedly and simultaneously treated to stimulate follicular growth and were prepared for OPU. Cumulus-oocyte complexes (COCs) were collected from one cow using a collection medium containing 5 µM U0126 and were cultured in medium supplemented with the same concentration of U0126 for the first 2 hr of IVM; COCs from the other cow were used as controls without U0126 treatment. The cows were exchanged between the two groups at every sequential OPU (n=8). The number of oocytes developing to blastocysts in the U0126-treated group (39.1%, 34/87) was significantly higher than that in the control group (22.1%, 19/86). Eight blastocysts produced with U0126 treatment were transferred to recipients, and four normal calves were obtained. The results indicate that embryos develop efficiently from OPU-derived oocytes treated with U0126, and that these embryos may be of practical use in calf production.