Lycopene incorporation into egg yolk and effects on laying hen immune function

Carotenoids are partially responsible for the colors of plants and when consumed by humans and animals are deposited into tissues (e.g., skin and egg yolk in laying hens) and may have health benefits. Because carotenoids are more available when consumed from egg yolk sources than vegetables, this research examined the ability of the laying hen to deposit dietary lycopene, a carotenoid that imparts red color in tomatoes, into the egg yolk and to investigate effects on immune function. All birds were housed in commercial cages, had ad libitum access to water, and were fed 100 g/bird per day. Experiment 1 consisted of 4 dietary concentrations of lycopene (0, 65, 257, and 650 mg of lycopene/kg of diet). High-performance liquid chromatography analysis confirmed that dietary lycopene was incorporated into egg yolks. Experiment 2 was a completely randomized design, with 3 concentrations of lycopene (0, 420, and 840 mg of lycopene/kg of diet) and 6 concentrations of alpha-tocopherol (0, 84, 164, 200, 284, and 364 mg of alpha-tocopherol/kg of diet). Egg yolk lycopene (P < 0.05) and vitamin E (P < 0.05) were increased with increasing dietary concentrations, whereas lutein and zeaxanthin concentrations remained constant. Immune responses (inflammatory, cutaneous basophil hypersensitivity, 1 degrees and 2 degrees antibody response) were induced but were not affected by dietary lycopene or vitamin E. These data indicate that lycopene can be incorporated into egg yolks, and at these dietary concentrations, alpha-tocopherol and lycopene may not affect the immune system of the laying hen.