207 OOCYTE RECOVERY RATES AND IN VITRO BLASTOCYST PRODUCTION IN CATTLE TREATED WITH A SINGLE INJECTION OF FOLLTROPIN-V DILUTED IN A SLOW-RELEASE FORMULATION

Abstract

We have previously shown that superstimulation of beef donors with a single intramuscular (IM) injection of Folltropin-V (Bioniche Animal Health, Belleville, Ontario, Canada) diluted in a proprietary slow-release formulation (SRF; Bioniche Animal Health) results in in vivo embryo production comparable with the traditional twice-daily IM administration over 4 days (Tribulo et al. 2010 Reprod. Fertil. Dev. 22, 367). Two experiments were designed to evaluate oocyte recovery and in vitro blastocyst production of oocyte donors superstimulated with Folltropin-V, administered in twice-daily injections or diluted in SRF and given by a single injection. In Experiment 1, crossbred beef cows (n = 11) and heifers (n = 5) were randomly allocated to 3 treatment groups in a crossover design (i.e. all animals were treated 3 times, and all treatments were represented in the 3 replicates). All donors had all follicles >8 mm in diameter ablated by ultrasound-guided follicle aspiration on Day 0, received 500 μg of cloprostenol (prostaglandin F_2α, Ciclase, Syntex, Argentina), and were treated as follows: Group 1 (multiple FSH): 160 mg of Folltropin-V divided into 4 IM injections administered twice daily (i.e. Days 1 and 2); Group 2 (single FSH): 160 mg of Folltropin-V diluted in 4 mL of 25% SRF and given by a single IM injection in the neck on Day 1; Group 3 (control): no FSH treatment. On Day 4, oocytes were aspirated from all follicles >3 mm in diameter by ultrasound-guided follicular aspiration, classified, matured in TCM-199 supplemented with 0.4% BSA, fertilized in Fert medium, and in vitro cultured in SOF supplemented with 0.4% BSA under oil at 37°C, 5% CO₂, 5% O₂, 90% N₂, and saturated humidity for 7 days. Data were analyzed by ANOVA. The mean (±SEM) numbers of follicles aspirated and oocytes recovered were higher (P < 0.05) in Groups 1 (multiple FSH, 13.6 ± 1.9 and 8.5 ± 1.0) and 2 (single FSH, 14.7 ± 1.7 and 9.4 ± 1.3) than in Group 3 (control, 8.7 ± 0.9 and 5.8 ± 1.0). The mean number of blastocysts after 7 days in culture was numerically higher (P = 0.2) in Groups 1 (2.1 ± 0.7) and 2 (2.6 ± 0.6) than in Group 3 (1.1 ± 0.4). In Experiment 2, lactating Holstein cows (n = 10) received 2.5 mg of estradiol benzoate and 50 mg of progesterone IM on Day 0. On Day 4, all cows received prostaglandin F_2α and were randomly allocated to 2 treatment groups, to receive 200 mg of Folltropin-V divided into 4 twice-daily IM injections or 200 mg of Folltropin-V diluted in 25% SRF and given as a single IM injection. On Day 7, oocytes were collected and treated like those in Experiment 1. The mean (±SEM) numbers of follicles aspirated (21.2 ± 3.5 and 14.4 ± 2.9), oocytes recovered (10.2 ± 1.2 and 13.8 ± 2.9), and blastocysts produced (4.6 ± 0.7 and 6.0 ± 2.0) did not differ for Groups 1 and 2, respectively (P = 0.3). In conclusion, superstimulatory treatment increased the number of cumulus–oocyte complexes available for IVF compared with no treatment, and ovarian superstimulatory treatment may be simplified by the use of a single IM dose of a sustained-release product, compared with multiple doses of a conventional product, without a reduction in the recovery or quality of cumulus–oocyte complexes.