248 SUPERSTIMULATION STRATEGIES FOR OVUM PICKUP IN HOLSTEIN DONORS

Abstract

In vitro embryo production (IVP) is an important tool to enhance genetic gain in cattle. However, oocyte quality is a limiting factor for the success of IVP programs in high-producing donors. A series of studies using protocols for follicular wave synchronization and superstimulation before ovum pickup were performed to improve the efficiency of ovum pickup and in vitro production in dairy cattle. The first study evaluated superstimulation with FSH (Folltropin-V®) before ovum pickup in lactating (n = 15) and non-lactating (n = 15) Holstein donors in a crossover design. Cows underwent synchronization of follicle wave emergence (FWE) and at the expected time of FWE, the FSH group received a total dosage of 200 mg of FSH in 4 decreasing doses 12 h apart; controls received no FSH, and ovum pickup was conducted 72 h after the expected FWE in all cows. The FSH-treated cows had a higher (P < 0.01) percentage of medium-sized follicles (6 to 10 mm) at the time of ovum pickup (55.1%) than control cows (20.8%) as well as lower cumulus‐oocyte complexes (COC) recovery rates (60.0 v. 69.8%, respectively; P = 0.002). However, FSH-treated cows had a higher blastocyst production rate (34.5 v. 19.8%; P < 0.01) and more transferable embryos per ovum pickup session (3.0 ± 0.5 v. 1.8 ± 0.4; P = 0.02). Subsequent trials evaluated plasma FSH profiles in 23 heifers and in vitro production following ovum pickup in 90 non-lactating Holstein donors superstimulated with a single IM injection of FSH in 0.5% hyaluronan (HA; MAP-5®, 50 mg). Controls received no treatment, while the F200 group received 200 mg of FSH in 4 decreasing doses 12 h apart. The F200HA and F300HA groups received 200 or 300 mg of FSH in 5 or 7.5 mL, respectively, of 0.5% HA by a single IM injection. Circulating FSH area under curve (AUC) in FSH-treated animals was greater than in the control group (P = 0.02). Although the AUC for F200 group did not differ from HA groups (P = 0.56), the total period of time plasma FSH levels were elevated was greater than in the HA groups (P < 0.01). In the IVP trial, FSH-treated cows had a greater proportion of medium-sized (6–10 mm) follicles than controls (P < 0.001). Also, numbers of follicles (P = 0.01) retrieved (control: 13.1 ± 1.0; F200: 16.5 ± 1.2; F200HA: 19.5 ± 2.1; F300HA: 15.4 ± 1.4; P = 0.01) and blastocysts produced per ovum pickup session (control: 2.4 ± 0.5; F200: 3.7 ± 0.7; F200HA: 4.7 ± 0.7; F300HA: 3.1 ± 0.6; P = 0.06) were greater in cows receiving FSH, regardless of treatment. Cows in the F200HA group had a greater recovery rate (P = 0.009), number of COC cultured (P = 0.04), and blastocysts per ovum pickup session (P = 0.06) than cows in the F300HA group. In conclusion, superstimulation of Holstein donors before ovum pickup increased the efficiency of in vitro production. Additionally, a single IM dose of FSH in 0.5% HA resulted in similar plasma FSH profiles to twice-daily FSH treatment. Non-lactating donors treated with FSH produced more embryos per ovum pickup session regardless of FSH treatment. Lastly, all in vitro-produced endpoints were greater following a single dose of 200 mg of FSH in 0.5% HA than 300 mg of FSH in 0.5% HA.