Effect of increasing doses of marigold (Tagetes erecta) flower extract on eggs carotenoids content, colour and oxidative stability

Two hundred and forty hens were assigned to six dietary treatments and fed a maize-wheat-soyabean diet supplemented per kg with 0, 150, 350, 550, 750 and 950 mg of marigold flower extract (MFE) containing lutein and zeaxanthin in the amount of 21.26 and 9.65 mg · kg^–1, respectively. There was observed no MFE addition effect on hens body weight and feed conversion ratio. The higher hen-day egg production was stated for group fed diet supplemented with 550 and 950 mg of MFE per kg of diet, whereas egg weight was increased in groups fed 550 and 750 mg MFE per kg of diet. The treatment effects on the albumen parameters, and yolk and shell percentages were not statistically significant. Dietary MFE addition increased the yolk colour score (DSM Yolk Colour Fan), and redness and yellowness of the yolks but decreased their lightness. Supplementation of MFE increased the lutein and zeaxanthin concentration in the egg yolks in a dose-dependent manner, from 12.34 and 5.92 mg · kg^–1 dry matter (control) to 36.33 and 25.59 mg · kg^–1 dry matter (group fed diet with 950 mg MFE per kg), respectively. No treatment effect on the concentrations of retinol and α-tocopherol in the yolk was observed. Dietary MFE significantly increased the oxidative stability of eggs lipids stored at 18 °C for 28 days. It can be concluded that 1. hen diet supplementation with MFE provides the yolk pigmentation required by consumers, and 2. MFE (in the amount of 550 mg · kg^–1 diet) is a suitable alternative to commercial synthetic xanthophylls.