Effects of dietary genistein supplementation on egg production and genistein, daidzein and lipid peroxidation levels in egg yolk in japanese quail

In the present study, we investigated the effects of genistein supplementation on the egg production, egg quality, malondialdehyde (MDA), vitamins A, E, and genistein and daidzein concentrations of egg yolk in quail. One hundred and fifty female Japanese quail (5 wk-old) were assigned randomly to 1 of 3 diets containing 0, 400, and 800 mg genistein per kilogram. The experimental period lasted 90 d with a 17L: 7D light: dark photo schedule. Egg yolk MDA, vitamins, genistein and daidzein concentrations were measured by high performance liquid chromatography using UV detector for MDA and fluorescence detector for soyisoflavones. Dietary genistein supplementation increased feed intake (P < 0.0001), egg production (P < 0.0001), egg weight (P < 0.0001), Haugh unit (P < 0.0001), shell thickness (P < 0.0001), shell weight (P < 0.0001) and improved feed efficiency (P < 0.0007) in quail. Egg yolk genistein content was increased (P < 0.0001), whereas egg yolk MDA concentration decreased (P < 0.0001) as supplemental genistein level increased. However, genistein supplementation did not affect egg yolk daidzein (P < 0.99), vitamin A (P < 0.80) and vitamin E levels (P < 0.14). There was an inverse relationship between egg yolk genistein and MDA concentrations (r = 0.651, P < 0.0001). Results of the present study indicate that supplementing with dietary genistein improved egg production and egg quality, egg yolk genistein content and decreased egg yolk MDA concentrations in quail.