Transvaginal Ultrasound-guided Ovum Pick-up (OPU) in Cattle

The technique of ultrasound-guided transvaginal follicular aspiration for ovum pick-up (OPU), is a non-invasive procedure for recovering oocytes from antral follicles in live animals. It was developed in the human [1,2] to assist human infertility. When people realized its application prospect, considerable researches have been aimed at applying this technology in the bovine. In 1987, an ultrasonic-guided aspiration of bovine follicular oocytes was first proposed in Denmark [3] and in 1988; a real OPU was first established in cattle by a Dutch team [4]. Together with in vitro fertilization of oocytes, OPU has been taken as a most flexible and repeatable technique to produce embryos from any given live donor. Unlike MOET, OPU does not interfere with the normal reproduction and production cycles of the donor. Any female starting from 6 months of age to the third month of pregnancy and even soon after calving (2-3 weeks) could be a suitable donor. It has been shown to be a feasible and practical alternative to the conventional multiple ovulation and embryo transfer (MOET) program [5,6], and it is being more and more used for commercial applications in the world [7,8].