IN-VITRO PRODUCTION OF BOVINE EMBRYOS FRO M OOCYTES COLLECTED BY ULTRASOUND-GUIDED OVUM PICK-UP ON LIVING COWS - PRELIMINARY-RESULTS

The in vitro production of bovine embryos from oocytes obtained by ult rasound-guided transvaginal ovum pick-up (OPU) was developed to offer an alternative for the in vivo production of embryos by superovulation . This study presents the preliminary results of the application of OP U in an experimental trial. Six heifers were punctured twice a week du ring 2 months (16 sessions). A general recovery rate (number of oocyte s per punctured follicle) of 58 % was obtained. The mean number of ooc yte/cumulus complexes (COC) recovered was 3.9 oocytes per cow and per session and varied significantly with the animal (P < 0.001). Seventy- two percent of the COC were of excellent or good quality. This percent age was not different between animals. A high rate (58 %) of transfera ble blastocysts was obtained after in vitro maturation, fertilisation and culture. An average of 20 (8 to 35) blastocysts was produced per a nimal in 2 months. The in vitro survival of those embryos after freezi ng and thawing was 65 %. Pregnancies were obtained after transfer (pre liminary data). This study indicates that OPU can be used for embryo p roduction and breeding in cattle. The main restrictive factors for the commercial application of this technique are the variable number of o ocytes-obtained and the cost of in vitro embryo production.