CAROTIN, THE PRINCIPAL YELLOW PIGMENT OF MILK FAT 369 



cow was in very poor flesh resulting from a feeding experiment in 

 which she was heavily underfed. Her ration during her underfeeding 

 was composed of alfalfa hay rich in carotin and xanthophylls and a 

 grain mixture of corn, bran and linseed meal. At the end of the 

 underfeeding experiment the ration was changed to bleached alfalfa 

 hay, the pigmentation of which was reported above, and white corn 

 and cottonseed meal. Enough of this ration was given to bring the 

 cow back to normal feeding conditions. At the end of this time the 

 experiment here reported was begun. The results are given in 

 Table 12. 



At the end of ten days the color of the milk fat had dropped to 

 9 units of yellow. When it was apparent after a week's further trial 

 that the color had reached at least a temporary minimum value for 

 this ration, the grain was changed to yellow corn entirely. This was 

 finally increased to 12 Ibs. per day. The result was very clearly in 

 accord with that of Experiment No. I, showing that yellow corn is 

 not a source of pigment for the milk fat of dairy cows. 



TABLE No. 12. EFFECT OF NON-PIGMENTED RATION AND A RATION CONTAIN- 

 ING YELLOW CORN UPON THE COLOR OF MILK FAT. AYR- 

 SHIRE Cow No. 301. 



(a) Oct. 3-21, white corn. 



(b) Oct. 24- Nov. 4, yellow corn. 



