Heterodimeric Fc fused porcine FSH improved the reproductive performance of gilts

Exogenous hormones are routinely administered to gilts to enhance reproductive performance by stimulating follicular development and ovulation. While equine chorionic gonadotropin (eCG) is the most widely used hormone for this purpose, its production-which involves blood collection from pregnant mares-lacks standardization and raises animal welfare concerns. This study aimed to develop a heterodimeric Fc-fused recombinant porcine follicle-stimulating hormone (rpFSH) as a sustainable alternative to eCG. The alpha and beta subunits of porcine FSH were fused to engineered Fc fragments and expressed in CHO-S cells. Site-specific mutations were introduced into the Fc domains to promote efficient heterodimeric assembly. A total of 120 Landrace × Yorkshire gilts were synchronized with altrenogest (ALT) for 18 days and randomly allocated to two groups: a control group receiving 1000 IU eCG followed by 100 μg GnRH 80 h later, and an rpFSH group receiving 1000 IU rpFSH (equivalent to 317 μg) plus 200 IU hCG, followed by GnRH on the same schedule. Transabdominal ultrasonography indicated that rpFSH-treated gilts developed significantly more 6.0-7.0 mm follicles (p < 0.05) but fewer follicles >7 mm in diameter compared to eCG-treated gilts. Hormonal analysis revealed 35 % higher FSH concentrations in the rpFSH group (p < 0.05), whereas estradiol and progesterone levels did not differ significantly between groups. The interval from GnRH administration to ovulation was longer in rpFSH-treated gilts (41.3 h vs. 36.7 h, p < 0.05). Reproductive outcomes were comparable between treatments, with pregnancy rates of 93.33 % in both groups. No significant differences were observed in farrowing rates (88.33 % vs. 91.67 %) or litter size (11.77 ± 1.56 vs. 12.35 ± 1.43 piglets). These findings demonstrate that the novel heterodimeric rpFSH, engineered via integrated hydrophobic and electrostatic steering strategies, provides a functionally equivalent and ethically superior alternative to eCG in gilt reproductive management.