Avian Renal Riboflavinuria: 7. Riboflavin-Binding Protein Transport and Half-Life

Abstract

THE transfer of riboflavin from blood to the yolk and albumen of the egg is dependent upon the presence of a riboflavin-binding protein (RBP) in the blood of the laying hen (Winter et al., 1967). Production of functional RBP is controlled by a single gene (Maw, 1954). The quantity of protein produced is a function of gene density. The level of RBP in heterozygous birds (Rdrd) is one-half that found in normal (RdRd) birds (Farrell et al., 1970a). RBP occurs in the blood of the RdRd and Rdrd hens only during the period of laying but can be induced in immature and mature males and females by injection of estradiol (Farrell et al., 1970b; Clagett et al., 1970). It has been postulated that the rdrd genotype transfers little or no riboflavin to the egg because, in the absence of RBP, the vitamin absorbed from the diet is eliminated by the…