Effects of antioxidants on the development of bovine IVM/IVF embryos in various concentrations of glucose

This study was undertaken to determine the effects of glucose, antioxidants and different oxygen tensions on the development of bovine embryos cultured in modified synthetic oviduct fluid (m-SOF) medium. In vitro matured (IVM) and fertilized (IVF) oocytes were incubated for 48 h. Embryos reaching at least the 4-cell stage were selected for further culture under various conditions for 6 d. Supplementing the m-SOF media with 4.5 mM glucose resulted in a significantly lower (P<0.01) embryo developmental rate (21 %; Day 8) than was obtained with 1.5 mM glucose (58 %; Day 8) or no glucose (53 %; Day 8). Antioxidants such as SOD, catalase and mannitol had no positive effect on embryo development in m-SOF medium supplemented with 1.5 mM glucose. However, in m-SOF medium supplemented with 4.5 mM glucose, SOD and mannitol significantly (P<0.05) improved embryo development: SOD increased the developmental rate from 19 to 35 % (Day 8), while mannitol increased it from 13 to 30 % (Day 8). Low oxygen concentration improved embryo development significantly (P<0.05) in m-SOF medium supplemented with 4.5 mM glucose (low O-2: 31 % vs high O-2: 14 %; Day 8) but not 6 mM glucose (low O-2: 58 % vs high O-2: 55 %; Day 8). Our data suggest that low concentration of glucose during culture of bovine embryos is beneficial, and that generation of free oxygen radicals is partly caused by a high concentration of glucose in the medium. (C) 1998 by Elsevier Science Inc.