Carotenoids and tocols in feed and egg yolk from barn, cage, and organic systems at different hen age

The hen egg is an easily available source of fat-soluble antioxidants such as carotenoids and tocols. Their amount and composition are influenced by several factors. Aim of the present research was to study the carotenoid and tocol compositions in egg yolk from Hy-line Brown hens reared in different housing systems (cage, barn, organic) throughout the whole hen laying cycle in relation to hen diets. Carotenoid and tocol profile in egg yolk and feed samples were analysed at 27, 30, 35, 43, 53, and 68 weeks of hen age by HPLC. Carotenoid and tocol contents in the feeds of cage and barn systems were similar but a decrease of carotenoid content in the feed of all housing systems occurred during the storage in silos. Both factors, housing system and hen age, had a significant influence on carotenoid and tocol contents in egg yolk, but the rearing system effect was generally predominant, because of the different feed characteristics in the organic production and of the intrinsic rearing conditions. All the carotenoids detected in feed were also found in eggs; organic feed and yolk were characterised by lower lutein and higher zeaxanthin and -criptoxanthin contents. As a result of lower deposition efficiency, barn yolks showed a carotenoid content (32.3±6.22 mg/kg) lower than cage and organic systems (39.0±10.77 and 39.4±5.11 mg/kg, respectively). While all tocol homologues were identified in feed, in egg yolk only α-, β-, γ-, δ-tocopherol and α-tocotrienol were found. Barn yolks showed a total tocol content (98.6±16.6 mg/kg) lower than cage and organic systems (133.9±20.74 and 135.8±11.3 mg/kg, respectively). A lower deposition efficiency of -tocopherol was observed in the eggs from the barn system.