Effects of daidzein on egg production and gonadotropin related gene expression in the ovary and follicles of laying hens

Summary Daidzein, as a dietary supplement, may promote laying performance and follicle development involving increased expression of gonadotropin receptor genes closely related to follicle development in laying hens after the peak laying period. Effects of daidzein on expression of mRNA of gonadotropin receptors in the ovary and follicles of laying hens were evaluated. A total of 768 56-week-old Hy-line Brown hens were randomly assigned to 4 groups with 8 replicates of 24 birds each. After 3 weeks of adaptation, the birds were given basal diets supplemented with 0, 10, 50 and 100 mg of daizein/kg for 12 weeks. Results showed that the laying performance reached the optimum at the doses of 50 mg/kg and the relative abundance of ER, FSHR, LHR and P450arom mRNA showed the same trend of variability. With the increase of daidzein dose, the expression quantity increased first, showed the highest level at doses of 50 mg/kg and then decreased. The expression of FSHR in granular layers and expression of ER in theca cell layers showed a significant increase with the increase of dose, while no statistically significant changes were seen in the expression of LHR and P450arom in SYF. These results indicated that dietary supplementation of daidzein at doses of 50 mg/kg showed the optimal effect on laying performance and gonadotropin related gene expression and this dose is considered to be the no observed adverse effect level (NOAEL) in the diet for laying hens.