MAMMALIAN CAROTENOIDS 



Feeding carotene to hedgehogs maintained on a carotenoid-free diet 

 increases the blood and Hver levels of both carotene and vitamin A, 

 but in spite of this only 3 per cent, of the dose can be accounted for. 

 It has not yet been decided whether this is due to inefficient conversion 

 of carotene into vitamin A or to inefficient absorption of the carotene. 



(g) Asses 



According to Manunta^^ the corpus luteum of an ass contained 

 only [3-carotene. 



(h) Dogs 



There is one report of carotenaemia in a dog ^ ^ ^ although only traces 

 of carotene, if any, are present in dog blood - ^ ^ and liver ^ ^ ^ and 

 bitches' milk does not normally contain carotene. ^ ^ ^ 



(/) Elephants 



Goodwin ^ ^ ^^ has found small amounts of a single carotenoid in the 

 fat of an elephant ; surprisingly this was not |3-carotene but was more 

 strongly adsorbed on alumina than this pigment, and had absorption 

 maxima at 445 and 425 mpi in light petroleum. It closely resembles the 

 unidentified carotenoid detected in human fat (see p. 231). It will be 

 interesting to see if this observation is confirmed when further experi- 

 mental material becomes available. No carotenoids were present in the 

 Hver lipids of the elephant. 



Mammals which Accumulate no Carotenoids 



Although they have attracted little attention, mammals which do not 

 accumulate carotenoids in their body tissue are much more common 

 than are those of the other groups. A survey of a large number of 

 mammalian livers by Jensen and With ^ ^ ' indicated that the majority 

 contain, either only traces or no carotenoids. 



The failure to accumulate carotenes is now considered to be due to 

 the efficient conversion of absorbed carotene into vitamin A in the gut 

 wall {see Chapter XI). The fate of ingested xanthophylls in this group 

 is not so clear (see p. 248). 



Amongst the most important animals in this group are 

 goats, 1. 1 7 3, 2 1 4. 2 1 6 swine, 217-220 j-ats, 221-224 rabbits, i' ^ 2 » hares, ^ 2 e 

 and guinea-pigs. 2 2 7 Sheep have been dealt with under "carotene 

 accumulators " but can really be considered borderline cases, for 

 even under the most favourable nutritional conditions their plasma 

 contains only traces of carotenoids and massive doses of carotene does 

 not appreciably increase this amount ^ (see p. 246). Foxes might 

 be placed in the same category as sheep, for they have very low plasma 

 levels and store no carotenoids in the liver. ^ ^ ® 



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