CAROTIN THE PRINCIPAL NATURAL YELLOW 

 PIGMENT OF MILK FAT.* PART III. ;, 



The Figments of the Body Fat, Corpus Luteum and Skin Secretions 



of the Cow. 



LEROY S. PALMER AND C. H. ECKLES 



Recent investigations in regard to yellow animal pigments have 

 shown that some of them are closely related chemically or identical 

 with yellow pigments of plant origin. Willstatter and Escher * have 

 found that the pigment of egg yolk is isomeric with a crystalline xan- 

 thophyll of green plants, and Escher 2 has found the pigment of the 

 corpus luteum to be identical with the widely distributed hydro- 

 carbon pigment, the carotin of fruits, flowers and green plants. 



In a study of the commonly observed yellow lipochrome of but- 

 ter fat we have found 3 that it is composed principally of a pigment 

 identical with carotin, with one or more minor constituents which 

 are evidently identical with the xanthophyll pigments. We have fur- 

 thermore shown by an unbroken chain of evidence that these pigments 

 are present in the milk fat as a result of feeding a ration containing 

 an abundant amount of these pigments. The presence of these pig- 

 ments in milk fat is therefore not due to any synthetic powers which 

 the animal possesses, but merely to the fact that the organism ab- 

 sorbs the pigments along with the products of food digestion and 

 subsequently secretes them dissolved in the milk fat. We were ac- 

 cordingly able to vary the amount of pigment in the milk fat by sim- 

 ply choosing the proper feeds, i. e., either deficient in carotin and 

 xanthophylls or very rich in these pigments. The above relations 

 between the carotin and xanthophylls of milk fat and the carotin 

 and xanthophylls of feeds were found to hold good for all breeds 

 of dairy cows. 



1. Zeit. f. Physiol. Chem. 76, pp. 214-225 (1912). 



2. Zeit. f.Physiol. Chem. 83, p. 198 (1913. 



3. Research Bulletin No. 10 Missouri Agr. Exp. Sta; Jour. Biol. Chem. 

 17, p. 191 (1914). 



*See Foreword, Part I, for statement of co-operation with Dairy Division, 

 U. S. Department of Agriculture. 



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