Dietary genistein improves laying performance, antioxidant capacity, and ovarian steroidogenesis in late laying hens.

This study evaluated the effects of dietary genistein supplementation on laying performance, eggshell quality, antioxidant capacity, and ovarian steroidogenesis in 66-week-old Hy-Line Brown laying hens. A total of 384 hens were randomly allocated to four treatments: a basal diet (control) or diets supplemented with 80, 120, or 400 mg/kg genistein, with 6 replicates of 16 birds each. Genistein supplementation at all levels significantly increased laying rate and reduced feed conversion ratio and broken egg rate (P < 0.05). Regarding egg quality, 80 and 120 mg/kg genistein decreased egg shape index, while all treatments increased shell ratio, and 80 mg/kg enhanced blunt-end shell thickness (P < 0.05). Plasma superoxide dismutase (SOD) activity was elevated by 80 and 400 mg/kg genistein (P < 0.05). In the liver, all genistein treatments increased SOD, glutathione peroxidase (GSH-Px), and total antioxidant capacity (T-AOC), and reduced malondialdehyde (MDA) levels (P < 0.05). In the ovary, 80 mg/kg increased GSH-Px activity, while 80 and 400 mg/kg enhanced catalase (CAT) activity (P < 0.05). Moreover, 80 and 120 mg/kg genistein increased plasma progesterone (P4) concentrations (P < 0.05). Expression of steroidogenic genes was also upregulated, with increased mRNA levels of steroidogenic acute regulatory protein (StAR), cytochrome P450 side-chain cleavage enzyme (CYP11A1), and 3β-hydroxysteroid dehydrogenase (3β-HSD). Corresponding increases in protein abundance were observed for StAR, CYP11A1, and 3β-HSD at specific supplementation levels (P < 0.05). In conclusion, dietary genistein improved laying performance and selected eggshell quality traits, enhanced antioxidant capacity, and was associated with increased plasma progesterone concentrations and altered expression of ovarian steroidogenesis-related factors in late-laying hens.