Abstract DURING recent years numerous studies have been made on the value of soybean meal as a supplement to relatively small quantities of animal protein in diets for laying chickens. Cottonseed meal, another vegetable protein concentrate produced in considerable quantities, has received little attention along this line, at least partly because of the substances in it that cause olive-colored yolks and pink yolks and whites in stored eggs. The appearance of olive-colored yolks in eggs laid by chickens receiving cottonseed meal was apparently first reported by Lamon and Lee (1917), and the responsible substance was first identified as gossypol by Schaible and co-workers (1934). The studies of Swensen and co-workers (1942) indicate the possibility of using iron salts to “tie-up” gossypol and thus eliminate it as a cause of olive-colored yolks. The recent report of Schaible and Bandemer (1946) shows that the substance responsible for pink yolks and whites is localized . . .