Improved embryo development in Japanese black cattle by in vitro fertilization using ovum pick-up plus intracytoplasmic sperm injection with dithiothreitol

The purpose of this study was to determine whether dithiothreitol (DTT) treatment of sperm and ethanolactivation improve embryo production by intracytoplasmic sperm injection (ICSI). Further, we compared ICSIwith standard in vitro fertilization (IVF) in oocytes obtained from cattle. We demonstratedthat DTT reduced the disulfide bond in the bovine sperm head. Using oocytes obtained from a slaughterhouse,ICSI-DTT treatment without ethanol showed the highest rate of blastocyst formation. We applied these resultsto fertilization using ovum pick-up (OPU). Eleven Japanese black cattle served as donors for OPU plus standardIVF (OPU-IVF). Of them, four donors with low embryo development rates were selected to determine whetherembryo development was enhanced by OPU plus ICSI (OPU-ICSI). We assessed effects on embryo developmentfollowing IVF and ICSI in oocytes obtained using OPU. Blastocyst rates were significantly higher for OPU-ICSIthan for OPU-IVF. Our results suggest that OPU-ICSI improves the blastocyst development rate in donors withlow embryo production compared with the standard OPU-IVF.