Use of ketone bodies as energy substrates at different developmental stages and under different oxygen tensions by in vitro-produced bovine embryos

Abstract

In vitro-produced bovine embryos can develop into hatched blastocysts in the presence of acetoacetate and b-hydroxybutyrate, which may be derived from lipid breakdown. The effects of these ketone bodies, added during different periods of early bovine embryo development and under different atmospheric conditions, were examined. In vitro produced bovine zygotes were cultured in modified-Synthetic Oviduct Fluid medium. Suplementation with 3.6 mM acetoacetate or b-hydroxybutyrate for 3 periods of culture gave blastocyst and expanded blastocyst rates comparable to controls with lactate/pyruvate. However, lactate/pyruvate produced higher blastocyst formation and expansion rates than ketone bodies when different proportions (10:1 and 1:10) of 3.6 mM acetoacetate/b-hydroxybutyrate and 3.6 mM lactate/pyruvate were used with either 20 percent O2 or 5 percent O2. However, no differences in development were attributable to redox status. When ketone bodies were added together in culture, lower blastocyst formation rates were obtained than using the same molecules as single substrates. It is concluded that bovine embryos can utilize ketone bodies at any period of early development and can develop withstanding different redox status.