Effect of medium change on the development of in vitro matured and fertilized bovine oocytes cultured in medium containing amino acids

Bovine in vitro matured and fertilized oocytes were cultured for 153 hr in groups of 3 or 30 in 30 mu l of modified synthetic oviduct fluid medium sup plemented with amino acids. The concentration of ammonium in culture medium at 153 hr of culture was significantly decreased by medium change at 72 hr of culture. However, regardless of embryo density, medium change had no be neficial or detrimental effect on the development of bovine embryos. Increa se in the development to blastocysts and production of ammonium were observ ed when embryos were cultured in groups of 30, These results indicated that the ammonium concentration detected in this culture system has a negligibl e effect on the development of bovine embryos to blastocysts.