Effects of glutamine, glycine and taurine on the development of in vitro fertilized bovine zygotes in a chemically defined medium.

The effects of glutamine, glycine and taurine on the development of bovine zygotes derived from IVM/IVF were determined using a protein-free chemically defined medium. After the cumulus cells were removed at 18 hr post-insemination, the presumptive zygotes were cultured for 4 or 6 days (about 104 or 154 hr) under a gas atmosphere of 5% O2: 5% CO2: 90% N2. A modified synthetic oviduct fluid medium supplemented with 20 amino acids (1 mM glutamine, essential amino acids for basal medium Eagle and non-essential amino acids for minimum essential medium), insulin, and PVA was used as a basic medium (mSOFai). Omitting 1 mM glutamine from mSOFai did not affect the embryonic development after 4 and 6 days of culture. After 4 days of culture, no significant effects of glycine and taurine on the development of zygotes to the morula stage were observed. However, supplementation with glycine or taurine significantly (P < 0.05) affected, with no interaction, the embryonic development to blastocysts after 6 days of culture. Addition of 5 mM glycine and 2 or 10 mM taurine significantly (P < 0.05) increased the percentage of blastocysts. The mean cell number in the blastocysts was affected by the glycine level, and was increased by the addition of 10 mM glycine (P < 0.001). These results demonstrate that glycine and taurine in a chemically defined medium containing a group of essential and non-essential amino acids improve the development of bovine zygotes to the blastocyst stage under 5% O2.