360 MISSOURI AGRICULTURAL EXP. STA., RESEARCH BULLETIN NO. IO 



ment in crystalline form. The pigment was isolated in the usual 

 way from forty grams of very high colored colostrum fat from a 

 Jersey cow. Great care was taken during the isolation to avoid 

 aldehyde resin pigments. This was successful. The ether solution 

 of the unsaponifiable substances was evaporated at 35 C. and the 

 residue dissolved at once in carbon bisulphide. This solution, which 

 had a blood red color, was concentrated to 2 c. cm. volume at a low 

 temperature and an excess of cold absolute alcohol added. There 

 was no immediate crystallization, but after standing several days 

 there were deposited a number of yellow crystals. These were at 

 first thought to be crystals of the pigment, for similar crystals were 

 obtained in the same manner from the corpus luteum pigment. The 

 crystals were perfectly formed double pyramidal forms, but proved 

 to be crystals of sulphur which evidently arose from the carbon bisul- 

 phide used. A further attempt at crystallization of the pigment was 

 abandoned. It undoubtedly would prove successful if sufficient pure 

 material could be obtained. 



THE RELATION BETWEEN THE COLOR OF THE MILK FAT 

 AND THE FOOD OF THE COW. 



General observation for no doubt hundreds of years, at least, 

 ever since butter has become of importance in the diet of man, has 

 shown that green feeds of all kinds, especially fresh green grass 

 greatly increase the color of butter fat. Other feeds, such as car- 

 rots, beets and yellow corn have been said to have the same effect. 

 It has never been the subject of a scientific investigation however, 

 to show just what relation exists between the food of the cow and 

 the color of the milk fat. With a chemical relation established be- 

 tween the milk fat pigments and carotin and xanthophylls, the rela- 

 tion of the color of the milk fat to the food seems to be readily 

 explained on the ground that the foods that have been observed to 

 cause the highest colored butter, namely, green foods, carrots, etc. 

 are those which are especially rich in carotin and xanthophylls, par- 

 ticularly carotin, as in the case of the carrots. Indeed we can go 

 still further and definitely state that these pigments must be abund- 

 antly present in the food before the milk fat will show a high color, 

 as will be demonstrated by the experiments which are about to be 

 reported. 



Character of the Yellow Pigments of the Common Cattle Feeds. 

 The chemical study of the yellow pigment of milk fat, shows that 

 its principal constituent belongs to the hydrocarbon or carotin group 

 of pigments, although it also contains xanthophylls as a very minor 

 secondary constituent. It accordingly became necessary to study the 



