Abstract

Objectives: To elucidate the role of SMAD8 in geese egg production, we analyzed the expression patterns of SMAD8 in geese during the egg-laying and non-laying periods.
Materials and Methods: LDN-193189, a specific SMAD8 inhibitor, was injected into the geese prior to the onset of egg-laying. Subsequently, the ovaries, oviducts, and serum of the geese at various reproductive stages were collected for subsequent detection and analysis.
Results: The results indicated that the development of ovaries and oviducts in geese during the egg-laying period was superior to that during the non-laying period. In addition, SMAD8 expression in ovaries and oviducts of egg-laying geese was significantly higher than that in non-laying geese (p < 0.05). Injection of the SMAD8 inhibitor LDN-193189 at a dose of 0.15 mg/kg body weight per day significantly inhibited SMAD8 expression. Concomitantly, the expression levels of follicle-stimulating hormone receptor (FSHR) and luteinizing hormone receptor (LHR) expression in the ovaries and oviducts were significantly increased (p < 0.05). Furthermore, the average egg production of geese was significantly increased by 4.1 eggs (p < 0.05), while the hatchability of breeder eggs remained unchanged (p > 0.05). Collectively, this study demonstrates that SMAD8 is differentially expressed at different reproductive stages in geese. Exogenous SMAD8 inhibitors can regulate in vivo SMAD8 expression, thereby modulating the expression of ovulation-related hormone receptors and ultimately improving the goose egg production.
Conclusions: These findings suggest that SMAD8 may serve as a key intracellular regulator connecting reproductive organ development, hormone receptor abundance, and egg-laying performance in Wanxi White Goose (WWG) and indicate that targeted modulation of SMAD8 activity could provide a novel strategy for boosting egg production in low-yield goose breeds without compromising hatchability.

Key words: Wanxi White Goose (WWG); folliculogenesis; ovary and oviduct; breeder egg hatchability