On the Supposed Effect of Iodocasein Upon Egg Production

THREE recent papers in this journal by Turner et al. (1945, 1945a. 1946) and a review by Reineke (1946) report experiments which led these writers to conclude that iodinated casein, a substance having the properties of thyroxine, has a marked stimulatory effect upon the production of eggs by domestic fowls. In most of the experiments this effect was believed to be exerted chiefly during the months of late spring and early summer, when production normally declines, but in one test (Turner et al., 1946, Lot IV) the treated birds laid better throughout the year. Since any such effect would have considerable economic value, it seemed desirable to repeat the experiments. THE EXPERIMENT Birds.—Single Comb White Leghorn pullets of the C and K strains resistant to lymphomatosis (Hutt and Cole, 1947) were utilized. The total number enrolled at the start of these trials was 401, these being divided in four . . .