Dairy By-products as Foods 255 



Skim -milk is the residue left after removing the 

 cream. It differs in composition according to the 

 composition of the original whole milk and the thor- 

 oughness of the creaming. The percentage of solids 

 which it contains is proportional in a general way to 

 the richness of the whole milk. At one time a con- 

 trary notion prevailed and the skimmed milk of the 

 butter breeds, especially the Jersey and the Guernsey 

 cows, was popularly supposed to be of inferior quality. 

 Numerous analyses have been made of this b}'- product 

 from several breeds, and the succeeding figures give 

 the proportion of solids and fat in skimmed milk from 

 the gravity process: 



Skimmed milk 

 Solids in Total 



■whole milk solids Fat 



% % % 



Holstein 12.22 9.50 .52 



Ayrshire 12.98 10.40 .85 



Jersey 15.24 10.50 .37 



These figures show most clearly that the Jersey 

 product is more valuable than that from Holstein cows, 

 volume for volume. 



Skim -milk is also affected by the manner or thor- 

 oughness with which the cream is removed. The more 

 perfectly the fat is taken out the less the percentage 

 of solids left behind and the less their unit value as 

 a source of energy. For these reasons gravity process 

 skimmed milk is often more valuable for feeding than 

 that from the separator, though under the best con- 

 ditions of skimming in both cases the difference is 

 small. 



Buttermilk, which is the residue after extracting 



