MAMMALIAN CAROTENOIDS 



high concentration of carotene ; in fact, '* carotene " was first obtained 

 crystalline from corpora lutea. ^ ' ' Ovaries contain as much as five 

 times more carotene than do testes, ^ ^ ^ this again may reflect dietary 

 habits. 



The liver carotene levels vary with the seasonal intake of carotenoids 

 as do the plasma and milk levels. ^ ^ ^ 



According to Studnitz, Neumann and Loevenich ^ ^ ^ and Bielig and 

 Busch 1 ^ * cattle retinas not only contain (3-carotene but also astaxanthin 

 and a pigment which has not been characterized satisfactorily but which 

 might be lactertofulvin {see p. 226) ; Brunner, Baroni and Kleiman, 

 however, could only detect (3-carotene, ^ ^ ^ probably in colloidal 

 solution. 1 ^ ® The iris contains p-carotene only. ^ ^ * 



The carotene in cattle muscle is not bound to protein and its con- 

 centration in muscle is 25 [ig. per 100 g. of tissue, which is a lesser 

 concentration than that in the blood plasma. ^ ^ ^ That carotene may 

 possibly be an excretory product in cattle is suggested by the fact that 

 it can be extracted from the yellow patches of olfactory tissue in the 

 upper region of the nasal cavity, ^ ^ * and from ear wax. ® 



Other Mammals 



Other mammalian species which preferentially accumulate carotene 

 in their tissues, although to a very much lesser extent than cattle, are 

 the horse, 1 » 5' 1 » « sheep, ^ »'- 1 » ^ Indian buffalo, ^^^ deer, i^* 

 antelope, ^ ^ ^ carabao, i » o. 1 2 o guinea pig, ^ " ^ and hedgehog. ^ 1 



(a) Horses 



Palmer 1^^ noted the preferential accumulation of carotenes in 

 horse plasma and Zechmeister and Tuzson^"* confirmed this in the 

 depot fat. In 1935 Zechmeister and Tuzson^o^ f^^^ ^ horse a large 

 amount of green fodder (carotenes and xanthophylls) and collected 

 both the jugular and portal blood at slaughter ; both samples contained 

 only carotene. Palmer and Eckles' considered that the accumulation 

 of carotenes was due to destruction of the xanthophylls as they traversed 

 the gut wall ; this may be true (for it appears to be so in rats (see p. 248) 

 but selective absorption probably plays a part because Zechmeister and 

 Tuzson^^® found the total carotenoids of horse dung to contain a 

 higher proportion of xanthophylls than did those of the fodder. The 

 carotene values of mares' plasma' follow the usual seasonal varia- 

 tions. 2 8 



(b) Guinea Pigs 



Guinea pigs' milk contains small amounts of carotenoids. ' ® * 

 Mitolo^o' claims that the carotene content of the liver of scorbutic 



245 



