584 IX. CAROTENOIDS AND VITAMINS A 



tive as vitamin A in the chick when the criterion of activity is growth. 

 On the other hand, Castano and co-workers^^' observed that vitamin A ex- 

 hibits a greater efficiency in the Hver storage test than does ;5-carotene. 

 Johnson et al.^^^ reported the opposite result, and Rubin and Bird^^* 

 found that /3-carotene and vitamin A were equally effective in this respect. 

 There appears to be little doubt that vitamin A is more readily absorbed 

 in the chicken than is carotene, especially when fat is absent from the 

 diet.^°^ Hogan^^^ contributed a critical review on the subject of vitamin 

 A requirements of chicks and of laying hens. 



The figures for the vitamin A requirement of turkey poults are consist- 

 ently higher than those for growing chicks. The following values (ex- 

 pressed as I.U./IOO g. food) have been recorded- growth, 440;-°* growth 

 and signs of deficiency, 300 to 500,««7 and SOO;''^^'^^^ growth and mortahty, 

 500 ;!<""' optimum growth for broad -breasted turkeys, and liver storage, 

 1700;^°" liver storage, deficiency symptoms, and mortahty, 1733, ac- 

 cording to Hinshaw and Lloyd, i*"'^ as cited by Hogan.^^^ Asmundson and 

 Jukes^""^ recommended 1000 I.U./IOO g. food as the proper level of vitamin 

 A in the ration of turkey poults, but the basis for reaching their decision was 

 not stated. Bird et al.^^^ estimated the satisfactory level for growing tur- 

 keys as 533 I.U./IOO g. food. According to Gurcay and co-workers,^"* 

 vitamin A acetate is four times as effective as ,S-carotene, and twice as ac- 

 tive as black-cod liver oil, in promoting growth in turkey poults. On the 

 other hand, vitamin A acetate was found to be twenty to thirty times as 

 effective as /3-carotene. and about twice as active as black-cod liver oil in 

 producing liver storage of vitamin A. However, Kramke et al.^^^ stated 

 that 500 I.U./IOO g. food was effective for optimum growth, whether the 

 vitamin A was given as the alcohol, as natural or synthetic esters, or in the 

 form of carotene in alfalfa or in wheat-germ oil. 



The vitamin A requirement of the North American quail or bobwhite 

 (Colinus (Ortyx) virginianus) was reported as 640 I.U./IOO g. feed, by Nest- 



886 M. Rubin and H. R. Bird, Poultry Sci., 20, 155-160, 291-297 (1941). 

 93e A. G. Hogan, Nutrition Absl. & Revs., 19, 751-791 (1950). 



8" R. Van Reen, M. W. Tavlor, and W. C. Russell, J. Nutrition, 43, 235-254 (1951). 

 998 W. C. Russell, M. W. Taylor, and R. Van Reen, Federation Proc, 8, 394 (1949). 

 989 E. H. Kramke, M. D. Llovd, and J. C. Fritz, Poultry Sci., 31, 49-53 (1952). 

 ™o H. S. Wilgus, Jr., Colorado Farm Bull, 2, 3-4 (1940). 



1001 F. D. Wharton, L. D. Matterson, H. M. Scott, and C. I. Bliss, /. Nutrition, 39, 

 543-554 (1949). 



1002 W. R. Hinshaw and W. E. Lloyd, Hilgardia, 8, 281-304 (1934). 



1003 V. S. Asmundson and T. H. Jukes, California Agr. Expt. Sta., Ext. Serv. Circ, No. 

 110, 1-78 (March, 1939), 



