PHYSICAL PROPERTIES OF MILK 



83 



butter and the rendered fat have a depth of color which is never 

 equaled at any subsequent stage of the lactation period. This 

 characteristic of colostrum milk is common to all breeds of 

 cows, and the high color of the fat continues in cows of all 

 breeds for a short time after parturition and then gradually falls 

 off. The next table gives the color of the milk-fat of several 

 cows shortly after parturition and again a week or two later. 

 The color readings are the Lovibond tintometer readings of a one- 

 inch layer of melted, rendered fat. 





Color of the Fat of Colostrum Milk 











Days 





Color 





Cow No. 



Breed 



Roughage 

 Fed 



after 

 Parturi- 





















tion 



Yellow 



Red 



Light 



301 



Ayrshire 



Alfalfa i 



4 



78.0 



3.5 



1.0 



301 



Ayrshire 



Alfalfa 



26 



71.0 



1.5 



0.5 



300 



Ayrshire 



Alfalfa 



4 



71.0 



3.5 



1.0 



300 



Ayrshire 



Alfalfa 



20 



68.0 



2.8 



1.0 



2 



Jersey 



Alfalfa 



13 



68.0 



2.6 



0.5 



2 



Jersey 



Alfalfa 



22 



57.0 



2.5 



0.5 



2 



Jersey 



Alfalfa 



2 



54.0 



4.3 



1.0 



2 2 



Jersey 



Alfalfa 



20 



50.0 



2.5 



1.0 



20 



Jersey 



Alfalfa 



2 



47.0 



4.8 



1.0 



20 



Jersey 



Alfalfa 



25 



47.0 



.2.0 



0.5 



206 



Hoi stein 



Alfalfa 



1 



50.0 



4.7 



0.3 



206 



Holstein 



Alfalfa 



5 



54.0 



2.0 



0.2 



In summing up the results of their work the authors draw the 

 following conclusions : 



1. The fat of cow's milk owes its natural yellow color to the 

 pigments carotin and xanthophylls, principally carotin, the well- 

 known, wide-spread, yellow vegetable pigments found accom- 

 panying chlorophyll in all green plants. 



1 The alfalfa hay was rich in carotin and xanthophylls. 



2 Second sample taken after next parturition. 



