228 



PRODUCTIVE FEEDING OF FARM ANIMALS 



While it does not lie within the scope of this book to discuss the 

 various factors that have a bearing on this production, it seems de- 

 sirable to state briefly the main influences that affect the value of 

 a cow in the herd in order that we may see more clearly what part 

 the feeding plays in the successful management of a dairy (Fig. 43). 



FIG. 43. Dairy cows of good breeding and well kept and cared for make excellent returns 

 "at the pail." 



Composition of Milk. Cows' milk is composed of the follow- 

 ing constituents: Water, butter fat, proteins (casein and albumen), 

 milk-sugar, and ash. The amounts of these components present in 

 milk of different origin, or even in milk from the same cow at 

 different times, vary widely. The limits of variation for normal 

 milk from American cows are about as follows : 2 



Composition of Cows' Milk, with Variations, in Per Cent 



2 Farrington-Woll, " Testing Milk and its Products," 22nd edition, p. 

 18; see also Wisconsin Research Bulletin 26, p. 62. 



