Effect of Different Sources of Vitamin D on the Laying Bird

Abstract

NUMEROUS investigators have reported on the influence of vitamin D in the nutrition of laying birds. These reports, without exception, show that ultraviolet light or vitamin D from fish oils exert a marked beneficial effect on egg production and hatchability. More recently it has been shown that the vitamin D of irradiated ergosterol is not so effective for the control of rickets in chicks as the rat unit equivalent from cod liver oil. These latter investigations show that it requires from 20 to 200 times as many rat units from irradiated ergosterol than from cod liver oil to give the same degree of protection. Branion and Smith (1932) and Titus and Nestler (1933) have also offered evidence that irradiated ergosterol is not so efficient as cod liver oil in promoting egg production and hatchability. The literature also contains reports that excessive doses of vitamin D from irradiated ergosterol may prove . . .