Effects of dietary supplementation with AOP on hormone indices of laying breeder hens. (A) Serum E2. (B) serum FSH. (C–F) The mRNA expression of hormone-related genes (ESR-β, FSHR, GnRH, and INH) in ovary. Different lowercase letters in the figure indicate statistically significant differences (p < 0.05, n = 6). Abbreviations: CON, control group, basal diet; AOP1, basal diet supplemented with 1 g/kg AOP; AOP3, basal diet supplemented with 3 g/kg AOP; E2, 17β-estradiol; FSH, follicle-stimulating hormone; ESR-β, estrogen receptor beta; FSHR, follicle-stimulating hormone receptor; GnRH, gonadotropin-releasing hormone; INH, inhibit 1.