COMMERCIAL FEEDING-STUFFS 



269 



Skim-milk and buttermilk are not greatly unlike in 

 richness in solid matter or in general composition. In 

 case the skim-milk is sweet, buttermilk differs from it 

 because in the latter the sugar has changed partially or 

 wholly to lactic acid. Whey is considerably poorer in 

 solids than the other dairy by-products and also differs 

 from them in the proportions of the several constituents. 



Skim-milk is the residue left after removing the 

 cream. It differs in composition according to the com- 

 position of the original whole milk and the thoroughness 

 of the creaming. The percentage of solids which it con- 

 tains is proportional in a general way to the richness of 

 the whole milk. At one time a contrary notion prevailed 

 and the skimmed milk of the butter breeds, especially 

 the Jersey and the Guernsey cows, was popularly sup- 

 posed to be of inferior quality. Numerous analyses have 

 been made of this by-product from several breeds, and 

 the succeeding figures give the proportion of solids and 

 fat in skimmed milk from the gravity process: 



TABLE LVII 



These figures show most clearly that the Jersey prod- 

 uct is more valuable than that from Holstein cows, 

 volume for volume. 



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



