Carrot leaves improve color and xanthophyll content of egg yolk in laying hens but are not as effective as commercially available marigold fortificant

Abstract

Yellow and orange egg yolks are good sources of xanthophyll carotenoids, consumption of which is associated with health benefits, such as cancer prevention, eye health, and bone health. Industrial feed fortificants used to improve egg yolk color and carotenoid concentration typically are derived from marigold flowers. Green leafy vegetables are also concentrated sources of the xanthophylls lutein and zeaxanthin (L+Z), but they have not been rigorously evaluated in laying hen feeds as a yolk colorant. The addition of food manufacturing byproducts, including carrot leaves, to animal feed is a promoted method of improving animal nutrition. The ability of dehydrated carrot leaves to improve egg yolk color and L+Z concentration was evaluated by feeding laying hens (n = 40) white maize-based feeds fortified with 2 different dehydrated carrot leaves, marigold as a positive control, or no fortificant as a negative control for 28 D. After a 7-D washout period, the hens were separated into 4 groups, and eggs were collected every other day. Yolks were analyzed by using a portable colorimeter to define the color space and by ultra-performance liquid chromatography to determine the carotenoid profile. Carotenoid concentration rapidly declined from day 0 to 8, confirming adequate washout conditions. The white maize negative control (WM) day 28 lutein concentration (3.59 ± 0.51nmol/g) was significantly less than orange-carrot leaf-treated (OCL) (5.34 ± 0.36nmol/g) and red-carrot leaf-treated hens (RCL) (5.92 ± 1.00nmol/g) in addition to the marigold-treated hens (MG). However, MG was significantly higher than both leaf-treated groups. From day 8 (3.93 ± 0.74nmol/g) to 28 (9.32 ± 1.66nmol/g), MG had the largest increase in lutein and was the only treatment to surpass day 0 initial concentrations (8.50 ± 1.64nmol/g). A similar trend was observed for zeaxanthin and was reflected in the color space.