Development of In Vitro Matured/In Vitro Fertilized Bovine Oocytes In A Simple Defined (KSOM) Medium

The experiments reported here take advantage of the large number of in vitro matured and in vitro fertilized (IVM/IVF) bovine oocytes which can be produced, permitting the design of controlled experiments to establish a simple defined medium for the study of early embryo requirements and to further test this medium as a component of co-culture. A total of 1386 IVM/IVF oocytes were used to compare a simple medium (KSOM) with complex culture conditions used successfully for culture of bovine embryos. All experiments were extensively replicated factorials. In Experiment 1, KSOM was equivalent to the complex Menezo B2 medium in producing blastocysts from IVM/IVF produced embryos and was superior to Menezo B2 medium when both were used with buffalo rat liver cells (BRLC), yielding 25% vs 8% blastocysts, respectively (P<0.05). In Experiment 2 a, KSOM was tested with 0 or 1 ng/ml of platelet derived growth factor (PDGF) and in Experiment 2 b, 0, 1 and 5 ng/ml of PDGF were tested. In Experiment 2 a blastocyst formation was higher (P<0.05) when PDGF was added to the co-culture and also was higher (P<0.05) for morulae plus blastocysts in Experiment 2 b when PDGF treatments were combined and compared to no PDGF. The results with the simple KSOM medium are sufficiently promising to indicate that growth factors, amino acids and other specific requirements of the embryo may be examined in future studies with KSOM as a base. Additionally, KSOM appears to be superior to Menezo B2 medium often used commercially for co-culturing bovine embryos with BRLC.