Improving Cryopreservation Efficiency and Pregnancy Rate through Superovulation with Follicle-Stimulating Hormone in Korean Hanwoo Cows via Ovum Pick Up

SIMPLE SUMMARY: Ovum pick up (OPU) methods play a significant role in oocyte collection worldwide and are the most efficient means of enhancing genetic advancement through maternal lines in cattle. The primary objective of this study was to establish an effective system for producing transferable embryos from high-quality cows using the OPU method. Oocytes were collected from Hanwoo cows, with one group administered follicle-stimulating hormone (FSH) and the untreated group serving as a control. The FSH group exhibited a higher proportion of grade A and B oocytes than those of the other grades, with most of the cumulus–oocyte complexes (COCs) at the germinal vesicle (GV) 2 stage. Additionally, the FSH group exhibited a significantly greater rate of blastocyst formation compared to the control group. The FSH group, after vitrification and in vitro culture, demonstrated superior re-expansion rates compared to the control group, showcasing the efficiency of FSH treatment in terms of embryo production, freezing, and preservation. ABSTRACT: The aim of this study was to devise an efficient technique for generating embryos from high-quality bovine females. Oocytes were collected from 20 control and 15 Hanwoo (Bos taurus coreanae) females treated with the FSH. A combination of decreasing FSH doses (36, 36, 24, and 24 mg, 12 h apart), progesterone, estrogen, and prostaglandins were administered to synchronize and mildly stimulate the animals. The FSH-treated group (1125 oocytes) and control group (1022 oocytes) exhibited a higher proportion of grade A and B oocytes (88.2%) than the other grades (p < 0.05), with most at the germinal vesicle 2 stage (64.0%). Moreover, the FSH-treated group achieved a notably higher blastocyst rate (44.7%) compared to the control group (31.1%) (p < 0.05). After undergoing vitrification and in vitro culture (IVC) warming, embryos in the FSH group exhibited higher re-expansion rates (grade 1: 86.9%; grades 2 and 3: 57.9%) compared to those in the control (p < 0.05). This highlights the positive impact of FSH treatment on in vitro embryo production (IVEP) and the OPU rate.