Ovum Pick-Up (OPU) in Cattle: An Update

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, especially in cows and mares. It was originally developed for assisted reproduction in the human species to assist infertility and was used for the first time in cattle in the Netherlands at the end of the decade of the 1980s. OPU does not interfere with the normal reproduction and production cycles of the donor and can be used in adult cows in various physiological states, in old animals with reproductive disorders of non-genetic origin and calves and heifers from 6 months of age. The repeated recovery of oocytes through OPU allows us to obtain the highest possible offspring of animals with high genetic value and speed up processes of animal selection and genetic improvement, while it is an extraordinary source of oocytes for cloning and transgenesis. It has been shown to be a feasible and practical alternative to the MOET (Multiple Ovulation and Embryo Transfer) program and it is being more and more used for commercial applications in the world. However, we must bear in mind that the implementation of an OPU program always requires the support of a specialized laboratory for embryo production. 140The aim of this chapter is to describe the most important aspects of the OPU procedure used in cattle considering its historical development, the actual situation of OPU worldwide, the OPU equipment and procedure, technical and biological factors influencing OPU results, other uses of OPU, potential risks and most common sequelae, a brief review about OPU in buffaloes, and finally some considerations about the future of OPU/IVEP (in vitro embryo production).