Choline Requirement and Synthesis in Laying Hens

INTRODUCTION SINCE its discovery in hog bile by Strecker (1862), the nutritional importance of choline has been increasingly recognized. It is considered by many nutritionists as a member of the B-complex group of vitamins and is a component of the widely distributed lecithin phospholipids found in egg yolk, liver, yeast, heart, brain and kidney (Best et al., 1932a, b, 1939; and Ewing, 1963). Choline also functions in methylation and demethylation reactions which are important in biological systems (Gillis and Norris, 1949; and Leach et al., 1966). It plays a vital role in growth promotion and as an antiperotic factor in chicks (Jukes, 1940a, b), and is involved in lipid mobilization in liver tissue of various animals (Atrom, 1958, 1960; Olson et al., 1958; Yoshida and Harper, 1960; Daghir and Balloun, 1961; Eric et al., 1965; and Rikans et al., 1965). To date, no quantitative requirement for dietary choline has been…