Transvaginal Ultrasound-Guided Ovum Pick Up (OPU) in Berkshire Breed during Natural Estrous Cycle

Transvaginal ultrasound-guided ovum pick up (OPU) has been widely utilized as a noninvasive and reliable technique that enables repeated retrieval of oocytes from live animals. To our knowledge, however, there are few reports of attempts to improve the follicle aspiration system for OPU in pigs. In this study, we examined the effects of different aspiration vacuum pressures and the phases of estrous cycle on oocyte recovery, the morphology of cumulus oocyte complexes (COCs), and blastocyst formation in Berkshire pigs. Firstly, three different vacuum pressures were used (60, 90 and 120 mmHg) and retrieved oocytes were classified based on their morphology of cumulus cells. There were no differences in the oocyte recovery rate among the aspiration vacuum pressures (5.3, 7.1 and 5.8 oocytes/head, respectively), however, the proportion of grade A oocytes (oocytes with several compact cumulus layers) in 90 mmHg (27.2%) was significantly higher (p