Transvaginal ultrasound-guided oocyte aspiration for production of embryos in vitro

There is still much to be studied and learned in the use of assisted reproductive technologies to maximize reproductive potential in genetically valuable animals (BEAL et al., 1992). Now that repeatable oocyte retrieval methods are being fine-tuned, it is likely these procedures will become routinely used to obtain oocytes for further gamete and embryo research and also by seedstock producers for in vitro embryo production from farm animals in the commercial sector. The use of transvaginal ultrasound-guided oocyte aspiration and IVF procedure does offer an alternative to cattle producers who have genetically valuable cows that for some reason are unable to produce viable embryos through standard embryo collection procedures. This technology can be used on oocytes harvested from older ovulating or nonovulating cows, females with physical injuries (e.g., fractured leg) and problem cows having an abnormal cervix. Good success has been reported using IVF procedures on oocytes obtained from supplemental follicles of cows with cystic ovarian disease. With IVF the potential exists for more embryos to be produced in a shorter period of time, since the procedure can be repeated on the same cow 3 to 4 times or more a month. At this station, we are harvesting oocytes from early postpartum (<40 days) beef and dairy cattle, before the female begins cyclic activity. The approach allows the opportunity to produce one or more extra calves from the cow before she is mated for a natural pregnancy. Currently, transvaginal ultrasound-guided oocyte aspiration is now being used to harvest valuable oocytes from minor farm animal breeds, from domestic females representing rare bloodlines, clinically infertile females and reproductively senescent cows. Research continues to find applications for this technology, including harvesting oocytes from young prepubertal heifers and early postpartum beef cows for in vitro embryo production. The use of ultrasound-guided oocyte aspiration should not be overlooked to obtain oocytes for in vitro embryo production and to aid in germplasm preservation of endangered exotic species.