Studies on Egg Quality : I : Introductory Note on Variations in Yolk Color

Abstract

That yolks vary in color has been known for a long time but the causes of these variations have received little consideration. Recently however they have assumed commercial importance, since during the last few years a premium has been paid in the New York market for eggs with pale yolks, their color being judged by their shadow when candled. This premium has frequently reached eight cents per dozen, and at least once reached twelve, a consideration of $1800 on a car of 500 cases. The new U. S. Egg Grades, (U. S. Dept. Agric., 1925) specify as one of the qualifications for the highest class of U. S. Specials, that the “yolk may be dimly visible,” while it is only for the fourth class, or U. S. Trades, that the “yolk may be plainly visible, dark in color.” An investigation of the factors influencing yolk color therefore is of decided . . .