COMPARISON OF RESPONSE OF TURKEY POULTS AND OF CHICKS TO DIFFERENT FORMS OF VITAMIN D1

The vitamin D requirement of turkey poults has been reported as 60 to 70 International Units per 100 gm. of feed by Baird and Greene('35), 200 A.O.A.C. Units per 100 gm. by Jukes and Sanford ('39) and 80 A.O.A.C. Units per 100 gm. by Hammond ('41) and by Carver and Rhian ('42). Baird and Greene ('35) used a fortified cod liver oil in determining the requirement not only of poults, but also of chicks and young pheasants. Their results with chicks would indicate the potency of this oil in A.O.A.C. Units to be the same as its potency in Interna tional Units. Jukes and Sanford ( '39) used U.S.P. Reference Cod Liver Oil and also a fish oil blend, and reported that a given number of A.O.A.C. Units of the latter was 1.4 times as effective for poults as the same number of A.O.A.C. Units of the former. This would indicate a difference in the ability of chicks and poults to use different forms of vitamin D similar to the difference long known to exist between chicks and rats. Such a difference would of course help to explain differences in requirements determined in different laboratories. Hammond ('41) found no difference between U.S.P. Reference Cod Liver Oil and a fortified cod liver oil. Carver and Rhian ('42) used a fortified cod liver oil in confirming the requirement reported by Ham mond ( '41). In both these investigations Activated Animal Provitamin D was also fed, but at levels which proved too high to permit accurate assessment of its potency. More recently Boucher ( '44) reported that a given number of A.O.A.C. Units of vitamin D of irradiated 7-dehydro-cholesterol or irradiated animal provitamin had much greater potency for turkey poults than did the same number of A.O.A.C. units of vitamin D of U.S.P. Reference Cod Liver Oil or a fortified sardine oil. The latter contained no vitamin D from any irradiation product and differe