Establishment of a Step-down FSH Superovulation Protocol in Microminipigs for Zygote Collection.

BACKGROUND/AIM: Domestic pigs have become increasingly important models in translational research; however, their large size presents logistical and ethical challenges. Microminipigs offer a practical alternative for long-term studies. This study aimed to develop an effective superovulation protocol using a step-down follicle-stimulating hormone (FSH) regimen to improve zygote collection in microminipigs.

MATERIALS AND

METHODS

In experiment 1, four female microminipigs with regular estrous cycles were used in both the control and treatment conditions in a crossover design. Treatment group was received prostaglandin F2α (PGF2α), followed by step-down FSH, and human chorionic gonadotropin (hCG). Follicle number, area, and diameter were monitored by ultrasonography from day -6 to day +1 of estrus. In experiment 2, three female microminipigs were used. Zygotes were retrieved at day 1 by oviduct flushing.

RESULTS

On day 0, the number of follicles was higher in the treatment group (93.0±7.74) compared to the control (46.8±5.01). Significant differences were observed on days -1 and 0, while by day+1, the number of follicles decreased in both groups. Follicle area was significantly larger in the treatment than in the control group (0.81±0.03 cm2 vs. 0.63±0.04 cm2) on day -2, with no significant differences detected on days 0 and +1. Follicle diameter was also significantly greater in the treatment group compared to the control (3.4±0.1 mm vs. 2.7±0.1 mm) on day -2, while no significant differences were found on days -1, 0, and +1. In experiment 2, an average of 14.7 zygotes per animal were recovered. The cleavage and blastocyst formation rates were 62.8% and 59.4%, respectively.

CONCLUSION

The step-down FSH protocol effectively enhanced ovarian response and embryo yield in microminipigs, marking a foundational step toward the efficient reproductive engineering for this animal model that may contribute to the advancement of translational research.