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

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 ≥7mm in diameter were aspirated for synchronization of wave emergence and cows received a norgestomet ear implant. After 36h, treatment with p-FSH (6 doses of 40mg each, 12h apart, i.m.) started. Ovum pick-up from follicles >2mm in diameter was performed 44h 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.