Practical use of OPU/IVP in modern cattle breeding

The presented results are obtained from OPU/IVP sessions at the RPN embryo transfer station during a 3.5 yr period. All together 5864 blastocystes wer e produced after 3437 OPU sessions. The efficiency of embryo production was influenced by many factors. There were big individual differences between donors regarding the number of aspirated oocytes and produced blastocystes. From cows were produced more embryos (1.97 per session) compared to heifer s (1.36 embryos/session). The change from TCM to SOF cultivation medium red uced the number of transferrable embryos from 1.75 to 1.6 but also the perc entage of the birth of heavy offspring from 15 % to under 1 %. The results indicate that OPU/IVP procedures can effectively replace conven tional embryo transfer. The best results can be achieved with a combination of one flushing and some following OPU/IVP sessions if the donor is alread y pregnant.