METABOLISM OF CAROTENOIDS AND VITAMINS A 565 



Table 7 



The Concentration of Carotenoids and of Vitamin A 



IN THE Yolks of Eggs, as Influenced by Diet" 



« J. Ganguly, J. W. Mehl, and H. J. Deuel, Jr., /. Nutrition, 50, 59-72 (1953), p. 66. 

 ' Including range of values in parentheses. 



" Proved, by mixed chromatograms and extinction curves, in n-hexane and carbon 

 disulfide, to be /3-carotene. 



Cruickshank and Moore^^'^ reported that the vitamin A content of eggs 

 was doubled by the incorporation of 10% of cod-Uver oil into the diet, and 

 that it was increased five times by the administration of a vitamin A con- 

 centrate. The augmentatory effect of supplementary vitamin A in the 

 diet on the amount of vitamin A in the egg was also recorded by Sherwood 

 and Fraps,^!^ as well as by Bethke et aU^^ The hens also laid 15% more 

 gggg 918 ]s^gff and co-workers^i^ reported that dietary vitamin A is trans- 

 ferred to the eggs more efficiently when given as vitamin A ester than when 

 administered as either vitamin A alcohol or carotene. 



When massive doses of vitamin A are given to chicks, a depression in 

 carotenoid deposition occurs.-"' This is reminiscent of the effect of similar 

 high doses of vitamin A on the milk and blood carotenoids of cows. In the 

 case of chicks, the carotenols rather than the carotenes are the carotenoid 

 pigments chiefly affected. When large dosages of vitamin A are incor- 

 porated in the diet of hens, a marked increase in the vitamin A content 

 in the yolks occurs concomitantly with a decrease in carotenoids. ^"^ The 

 results of these experiments are summarized in Table 8. 



The vitamin A content of the eggs was doubled when the hens received 

 food containing 100,000 I.U. of vitamin A per pound, and was somewhat 

 further increased when the level of supplementary vitamin A in the food 

 Avas 200,000 I.U. per pound. The maximum level of vitamin A noted in 



9" E. M. Cruickshank and T. Moore, Biochem. J., 31, 179-187 (1937). 

 918 R. M. Sherwood and G. C. Fraps, Texas Agr. Expt. Sta. Bull, No. 493, 5-22 (1934). 

 "9 R. M. Bethke, D. C. Kennard, and H. L. Sassaman, J\ Biol Chem., 72, 695-706 

 (1927). 



