Treatment of ovine oocytes with certain water-soluble vitamins during in vitro maturation (IVM)

The main aim of this study was to evaluate the effects of water-soluble vitamins (singly or in combination), on in vitro maturation (IVM) and subsequent embryonic development of sheep oocytes. Cumulus oocyte complexes (COCs) were evaluated in three experiments. Experiment 1: COCs were matured in modified synthetic oviduct fluid maturation medium (mSOFM), with or without various protein supplements (polyvinyl alcohol (PVA) + mSOFM: defined maturation medium, DMM; BSA + mSOFM: semi-defined maturation medium; SDMM and FCS + mSOFM: undefined maturation medium; UDMM). Experiment 2: COCs were matured in mSOFM with or without various protein supplements containing 1× minimal essential medium (MEM) vitamins. Experiment 3: COCs were matured in SDMM with the addition of certain water-soluble vitamins (pantothenate, riboflavin, and thiamin), singly or in combination. The COCs were co-incubated with epididymal sperm of rams in SOFF (synthetic oviduct fluid fertilization) media, with 10% heat-inactivated estrous sheep serum for 22–24 h. Embryos were cultured in a SOFC1 (culture 1) medium for 48 h, followed by culture in a SOFC2 (culture 2) medium for 6 days. The addition of BSA-V to mSOFM (SDMM) improved the mean blastocyst formation, compared to other treatments. The presence of 1× MEM vitamins in SDMM increased the blastocyst formation rate, compared with DMM, UDMM, and mSOFM. The presence of single vitamin (pantothenate) in the SDMM improved blastocyst rate formation, compared with SDMM + thiamin; SDMM + pantothenate plus thiamin; SDMM + riboflavin plus thiamin; and SDMM + all three vitamins together. This is the first report to show the stimulatory effect of certain single vitamins on the in vitro development of matured ovine oocytes.