582 IX. CAROTENOIDS AND VITAMINS A 



liver. Preformed vitamin A was found to be six times as effective as caro- 

 tene in promoting storage of vitamin A in the liver. 



{d) Rabbit. Although Pirie and Wood^^^ demonstrated that the labbit 

 requires vitamin A, no quantitative data are available. In the case of 

 animals on vitamin A-free diets, impairment of growth, corneal lesions, and 

 reduction of the ascorbic acid content of the aqueous humor were noted. 

 Rabbits fed on a \dtamin A-free diet were maintained in a satisfactory 

 state of health when they were supplemented with carotene in an amount 

 of 50 /ig./kg. of body weight/day. ^'^^ The remedial dose was considerably 

 more than 70 ixg. 



(e) Dog. On the basis of the rate of depletion of the vitamin A supply 

 in the liver, Crimm and Short^''^ cited the daily requirement of the dog as 22 

 to 47 I.U. of vitamin A/kg. of body weight. Frohring^'^'' cited a figure of 

 100 I.U./kg./day, based upon liver storage of vitamin A. On the other 

 hand, Morgan^'^^ recorded a value of somewhat over 800 I.U./kg./day when 

 "optimum health" was the criterion, while Michaud and Elvehjem^'^^ esti- 

 mated the requirement as 20 ng,. (66 I.U.) per kg. body weight as vitamin 

 A, or 40 to 60 ng. (66 to 100 I.U.) per kg. weight using /3-carotene as the 

 source of the vitamin A. The deficiency symptoms in the dog included 

 loss of appetite, eye infections, a peculiar, divergent strabismus, atoxia, 

 nervous running around the cage in circles, as well as the usual skin symp- 

 toms and corneal lesions. 



(/) Chickens, Turkeys, and Other Fowl. The estimates of the require- 

 ment of fowl for vitamin A have been made under two categories, i.e., that 

 of the young growing bird and that of the adult birds, including the laying 

 hen. With and Wanscher^^" found that chicks required 100 to 200 I.U./kg. 

 body weight daily for growth, and 210 I.U./kg. weight for adequate liver 

 storage. When growth is used as the main criterion, and the estimates are 

 based upon I.U./IOO g. feed, there is a wide range in the estimates for 

 chicks, varying from a low figure of 87 I.U./IOO g. food^^^ to a high value 

 of 355.^^^ Other estimates based upon growth fall between these extreme 



"4 A. Pirie and C. Wood, Biochem. J., 40, 557-560 (1946). 



9" P. H. Phillips and G. J. Bohstedt, /. Nutrition, 15, 309-319 (1938). 



"« P. D. Crimm and D. M. Short, Am. J. Physiol, 118, 477-482 (1937). 



"7 W. O. Frohring, Vet. Med., S2, 76-82 (1937). 



"8 A. F. Morgan, North. Am. Veterinarian, 21, 476-486 (1940). 



"9 L. Michaud and C. A. Elvehjem, Nutrition Abst. & Revs., 13, 323-331 (1944). 



9«> T. K. With and O. Wanscher, Vitamine u. Horynme, 4, 341-366 (1943). 



9" G. E. Bearse and M. W. Miller, Poultrij Set., 16, 34-38 (1937). 



982 E. L. Johnson, C. W. Carrick, and S. M. Hauge, Poultry Sci., 27, 308-314 (1948). 



