376 



FUNDAMENTALS OF AGRICULTURE. 



country do not, however, belong to any special breed of 

 cattle, but are of mixed breeding, and known as native 

 cows or scrubs. 



Milk. Milk is a complete food intended by nature 

 for the nourishment of the young calf. Man has taken 

 advantage of the faculty of milk secretion by cows, 

 and through careful feeding, breeding and selection he 

 has gradually developed this faculty, so that cows now 

 yield far more milk than is needed for their offspring. 

 Some cows have produced ten to fifteen times their 

 own weight of milk during a year, or over 20,000 

 pounds of milk in all, but most cows give less than one- 

 fourth this quantity annually. 



Composition of Milk. Milk is composed of the fol- 

 lowing substances : water, fat, casein and albumen, milk 

 sugar, and ash. The composition of the milk varies 

 considerably with the breed of the cow and other fac- 

 tors. One hundred pounds of American milk contains, 

 on the average, the following quantities of different 

 components : 



Water 87.4 pounds 



Butter fat 3.7 ] 



Casein and albumen .... 3.2 



Milk sugar 5.0 " 



Ash 0.7 " 



Total solids 12.6 pounds 



FAT GLOBULES IN MILK, AS SEEN WITH THE AID OF A MICROSCOPE: 

 THE GLOBULES IN THE CIRCLE ARE THE MORE HIGHLY MAGNIFIED. 



