The Utilization of Carotenoids by the Hen and Chick

THUDICHUM (1869) observed that the pigment in egg yolk was unsaponifiable and was exclusively soluble in fat solvents and gave it the name lutein. Schunk (1903) isolated the egg yolk pigment and showed by spectroscopic study that it was xanthophyll. Kuhn et al. (1931) reported, in contrast to Schunk (1903), that the pigment of the egg yolk was not a single carotenoid, but that the egg yolk contained zeaxanthin in addition to the lutein. Palmer and Kempster (1919) later demonstrated that the carotenoids which are present in egg yolks depended on the carotenoids fed. Mann (1946), and Brown (1938) have subsequently demonstrated that, in general, hens deposit in the egg yolk at least part of any carotenoids consumed. Most of the early work on avian carotenoid metabolism has been done with “total carotenoids” or “total xanthophylls,” or with crude carotenoid extracts and concentrates. However, some work has been done with…