Short communication: Follicle superstimulation before ovum pick-up for in vitro embryo production in Holstein cows

Abstract

The objective was to evaluate in vitro embryo production (IVEP) in nonlactating Holstein cows after ovarian superstimulation. Cows were randomly assigned in a crossover design to 1 of 2 groups: control (n = 35), which was not synchronized and not treated with hormones before ovum pick-up (OPU), or hormone-treated (n = 35), in which wave emergence was synchronized and animals treated with porcine (p)-FSH in the presence of norgestomet before OPU. In the hormone-treated group, all follicles ≥7 mm in diameter were aspirated for synchronization of wave emergence and cows received a norgestomet ear implant. After 36 h, treatment with p-FSH (6 doses of 40 mg each, 12 h apart, i.m.) started. Ovum pick-up from follicles >2 mm in diameter was performed 44 h after the last p-FSH (coasting). Then, IVEP was performed. The total number of cumulus-oocyte complexes recovered (16.0 vs. 20.5 ± 2.2) and number of grades I to III (viable) oocytes (10.7 vs. 12.3 ± 1.6) did not differ between hormone-treated and control groups Additionally, no differences were found in the number of blastocysts per cow per OPU (3.0 vs. 2.6 ± 0.5) or in blastocyst rates (17.1 vs. 12.2 ± 2.4%) between hormone-treated and control, respectively. Thus, in this study, ovarian follicle superstimulation with p-FSH followed by coasting in nonlactating Holstein cows that had synchronization of wave emergence and progestin supplementation did not improve oocyte quality or IVEP compared to no hormonal treatment.