MISSOURI AGRICULTURAL EXP. STA. RESEARCH BULLETIN NO. 12 



plays in the formation of the milk fat. The same holds true for the 

 body fat. 



The readily demonstrated fact that the withdrawal of carotin 

 from the food results in a marked decrease in the color of the milk 

 fat being secreted or in the body fat being formed, shows that the 

 albumin which carries the carotin in the blood serum does play a 

 definite part in the formation of both milk fat l and body fat and no 

 doubt also in the formation of the corpus luteum. 



The whole phenomenon offers many difficult and interesting prob- 

 lems for future study. Many of these when solved will undoubtedly 

 throw light upon the chemistry of the mechanism of milk secretion. 



SUMMARY. 



1. The well-known lipochrome of the blood serum of the cow is, 

 like the lipochrome of the milk fat, body fat, etc., of the same animal, 

 composed principally of carotin, the widespread hydrocarbon pigment 

 of plants. Associated in small quantity with the carotin of the serum, 

 probably dissolved in the fat of the blood, are one or more xanthophyll 

 pigments, which are always found in more or less variable quantities 

 associated with the carotin of plants. 



2. The carotin and xanthophylls of the blood serum are derived 

 from the food and furnish the normal source for these pigments in 

 the milk fat and body fat, etc. A variation in the quantity of these 

 pigments in the food results in a corresponding variation in the amount 

 found in the blood serum and milk fat. Body fat formed during this 

 time will be also affected. 



3. The carotin is carried by the blood serum in combination with 

 an albumin. The combination is a very firm one. Lecithin and cho- 

 lesterol are probably a part of the combination. We propose the name 

 caroto-albumin for this new chromo-protein of the blood. 



4. The caroto-albumin of the blood serum of the cow is probably 

 of importance in the formation of the milk fat, body fat and corpus 

 luteum of the cow. It is doubtful if this new pigmented protein is 

 of importance in the oxygen respiration of the body. 



5. The lactalbumin of cows' milk may, among other factors, 

 be related to the color of the milk fat. There appears to be a special 

 relation here in connection with the high color and the high albumin 

 content of colostrum milk. 



1. The presence of both cholesterol and lecithin in the caroto-albumin may 

 explain the origin of these lipoids, as well as carotin in butter fat. 



