The Effect of sperm preparation and brief gamete coincubation length on ovine oocytes fertilization, subsequent development and embryo quality

Abstract

Over the past 70 years, egg yolk (EY) is frequently used as a cryoprotectant in semen diluents and has been confirmed highly effective for the maintenance of sperm fertility. However, the preparation of uniform diluents containing EY is hard. Since Cheng, (1985) reported the beneficial effect of overnight gamete oocytes coincubation length in IVF, this protocol was used a recommended protocol in several species. However, this protocol leading to exposure of oocytes and embryos to toxic effects associated with excessive generation of reactive oxygen species. The aims of this study were to examine (i) whether brief exposure of mature ewe oocytes to frozen-thawed semen prepared with different semi-defined diluents may affect fertilization, enhanced embryonic development, embryo quality before and/or after freezing vs. long coincubation length, and (ii) explore the accompanying effects of different semi-defined diluents and coincubation length on fertilization and embryo development rates