REQUIREMENTS OF ANIMALS 581 



Table 10 



The Effect of the Vitamin A Intake on the 



Average Survival Time of Male and 



Female Rats" 



" H. E. Paul and M. F. Paul, /. Nutrition, 31, 67-78 (1946). 



It is thus obvious that the optimum requirement of the rat for vitamin 

 A has been reported at values varying between 10 and 100 I.U. per kg. 

 per day, depending upon what criterion is used for the assessment. The 

 usual criteria, such as good growth and prevention of deficiency symptoms, 

 can be satisfied when daily intakes between 20 and 100 I.U. per 100 kg. 

 body weight are used as the basis. 



(6) Mouse. According to McCarthy and Cerecedo,^^^'^'- the vitamin A 

 requirement of the mouse is somewhat less than one I.U. per animal pei 

 day. The weanling mouse is able to withstand long periods of vitamin A 

 depletion because of the large, initial embryonic stores present at wean- 

 j,^g 973 j^ -^.g^g recorded that more stringent conditions are required to 

 produce deficiency in the mouse than in the rat.^''* When the young from 

 mothers on a vitamin A-deficient diet were continued on the same diet, 

 death occurred in some cases before the development of any extensive 

 changes in the epithelium, or of structural changes in the eye; however, 

 some injury did occur to the eyes, as evidenced by the production of a thick, 

 clear, colorless exudate. The reproductive fmiction in the male mouse is 

 especially sensitive to a deficiency in vitamin A; however, one I.U. is 

 quite adequate for the normal sex function in the male."^ 



(c) Guinea Pig. Little is knowni about the requirements of the guinea 

 pig for vitamin A, although Mannering^^" recorded the fact that this species 

 requires a frequent intake of the vitamin in the diet. According to Bentley 

 and Morgan,*^^ at least 2 mg. of carotene (3330 I.U.) per kg. body weight 

 are required before an appreciable amount of vitamin A is stored in the 



"' P. McCarthy and L. R. Cerecedo, Federation Proc, 9, 364 (1950). 



''2 P. T. McCarthy and L. R. Cerecedo, J. Nidrilion, 49, 357-367 (1953). 



"5 P. T. McCarthy and L. R. Cerecedo, J. Nutrition, 46, 361-376 (1952). 



