228 Effects of follicular superstimulation on ovum pickup–in vitro-produced outcome in German Fleckvieh heifers

Follicular wave synchronization and follicular superstimulation by FSH are both routinely used nowadays to maximize results in ovum pickup–in vitro-produced (OPU-IVP) programs. Studies conducted so far analysed either dairy or beef cattle, and results were sometimes inconsistent. Herein we investigated the effect of follicular superstimulation preceded by follicular wave synchronization on OPU-IVP outcomes in German Fleckvieh, a dual-purpose breed with high milk and beef performance. Twelve German Fleckvieh heifers (mean age ± s.d.: 484 ± 62 days) were enrolled and underwent routine OPU-IVP twice 7 weeks apart in a crossover design (control cycle and superstimulated cycle). Starting on a random day of the cycle, all heifers received 0.5 mg of cloprostenol (Day 0) and 10 µg of buserelin (Day 2), respectively, for follicular wave synchronization. Then, six heifers were randomly chosen for follicular superstimulation before the first OPU, while the others were superstimulated before the second OPU. Follicular superstimulation was done using four injections of each 75 IU of FSHp and 75 IU of LHp (1.5 mL IM, Pluset, Calier) 12 h apart, on Days 4 and 5, and a coasting period of 40 h was allowed before OPU. Statistical analysis was performed using SPSS software and the nonparametric Mann–Whitney test was employed to test for the effect of treatment (control vs follicular superstimulation) on recovery rate, number of oocytes, oocyte quality (grade 1–4), cleavage rate, blastocyst rate and blastocyst quality. Results are presented as mean ± s.e.m. A similar oocyte recovery rate was achieved in both groups (58.9% control, 59.1% superstimulated; P = 0.98) resulting in 13.2 oocytes/control cycle and 14.8 oocytes/stimulated cycle (P = 0.71), respectively. There was a tendency (P = 0.07) for more excellent quality oocytes in the superstimulated versus control group (7.9 ± 2.4 vs 2.9 ± 0.6), but no difference regarding their cleavage (83.6 ± 3.8% vs 84.6 ± 4.2%; P = 0.80) or blastocyst (40.3 ± 4.5% vs 42.9 ± 6.8%; P = 0.93) rates. The total number of transferable embryos was numerically but not significantly higher (4.8 ± 1.1 vs 4.1 ± 0.9; P = 0.67) in the superstimulated group compared with the control. In conclusion, our results demonstrate no positive effect of follicular superstimulation in addition to follicular wave synchronization on OPU-IVP outcomes in the dual-purpose breed German Fleckvieh. Although the number of animals enrolled in this study was relatively small, these results suggest limited beneficial effects of superstimulation before OPU-IVP in German Fleckvieh heifers.