Effect of Sources of Vitamin D on Storage of the Antirachitic Factor in the Egg

THE importance of egg yolk as one of the richest food sources of vitamin D has been repeatedly stressed by Hess (1923 a and b, 1924) and others who have made use of it as a prophylactic and curative agent in studies on rickets. Because of this fact and because so few potent natural sources of vitamin D are known, practical poultrymen and nutritionists have been interested in attempts to enrich the yolk in this vitamin either by feeding the hen supplements rich in vitamin D or by increasing the amount of ultra-violet light that she receives. The amount of the antirachitic factor supplied by either one of these two methods has been shown to have a definite influence on egg production, vitamin storage, hatchability, and shell texture. By means of curative and prophylactic tests on rats, Bethke, Kennard, and Sassaman (1927) determined that eggs from White Leghorn hens given . . .