What Do You Lose When You Lose Your Language

In vitro and in vivo developmental competence of fresh and cryopreserved in vitro produced (IVP) bovine embryos was evaluated up to birth. Three experiments were done. The objective in the first experiment was to develop an optimal vitrification procedure for IVP bovine embryos by determining effects of exposure time (2, 5, 10, 20 min) and temperature (4, 22, 27 degrees C) in cryoprotective agents prior to vitrification on their post-thaw viability. The best combination was used in Experiments 2 and 3. In the second experiment, the importance of post-thaw morphologic selection on pregnancy rates was determined by transferring either selected or unselected single embryos. In the third experiment, pregnancy initiation, maintenance and calving results of vitrified embryos were compared with fresh and conventionally frozen embryos. Fetal losses, birth weights, gestation lengths and frequency of dystocia in the third experiment were monitored. The interaction of exposure time and temperature on both post-thaw re-expansion and hatching rates was significant (P 0.05). However, pregnancy rate of conventionally frozen embryos was lower than that of fresh or vitrified embryos (P 0.05). Twin-born calves were lighter than single-born calves (P < 0.05). Overall, the data demonstrate that the transfer of vitrified IVP bovine embryos can result in healthy, apparently normal calves similar to those derived from transfer of fresh and conventionally frozen IVP bovine embryos.