Culture of equine embryos in media containing egg yolk, mare's milk and saline: Preliminary results

A medium containing egg yolk, mare's milk and/or modified PBS was used to culture Day-8 to 8.5 equine blastocysts. Twenty-one variants of the medium containing different concentrations of the 3 components were prepared. Embryos were recovered nonsurgically and placed into the media at 37 degrees C for 24 h. A total of 45 embryos was cultured; of these 7 died in culture and 13 showed inadequate development at the onset, while 25 continued to grow in the media. It was established that embryos grew best in media containing 20 to 60% yolk, 20 to 60% mare's milk and/or 20 to 60% PBS. It was found experimentally that egg yolk was the main component of the media, while mare's milk and PBS were interchangeable. Two mares became pregnant after transfer of 1 cultured blastocyst per mare. One of the mares lost the fetus at 9 mo, while the other carried the fetus to term and foaled normally.