The effects of non-saponified lutein from marigold flower meal (MFM) and saponified lutein from marigold flower extract (MFE) on chicken egg yolk coloration was evaluated. A total of 90 laying hens were randomly divided into 9 groups: the basal diet (0mg/kg lutein; control) was supplemented with 10, 20, 30, and 40mg/kg lutein from MFM or MFE. During the three-week feeding experiment period, birds had free access to feed and water, and feed consumption and egg production were recorded weekly. Five eggs per group were evaluated weekly for egg quality such as shell-breaking strength, shell thickness, shell ratio, albumen ratio, yolk ratio, yolk color, and Haugh units. The egg yolk color was visually examined using the Roche Yolk Color Fan. The egg yolk color was further examined for yolk color, yellow index, lightness (L*), redness (a*), yellowness (b*), ratio of redness to yellowness (a/b), chroma, and spectrum wavelength reflectance using a spectrophotometer, an objective method. Feed consumption, body weight, egg production, egg mass, and egg quality with the exception of egg yolk color were not affected significantly by the dietary treatments. Compared with the yolk color parameters of the control, those of the dietary treatment groups tended to be higher; and the 40mg/kg lutein from MFM group and the 20, 30, and 40mg/kg lutein from MFE groups were significantly increased (P<0.001). In two-way ANOVA, the visual and objective egg yolk colors, a* and a/b were improved by both the dietary lutein treatment (P<0.05) and the lutein supplementation levels (P<0.001).
It was concluded that dietary lutein enhances egg yolk color at levels of approximately 30 to 40mg/kg, and that saponified lutein from MFE appears to be more effective in egg yolk color than non-saponified lutein from MFM.