226 



Feeds and Feeding. 



III. Cow's Milk and its By-products. 

 Digestible nutrients and fertilizing constituents. 



* Casein and albumen. f Milk sugar. J Fat. 



349. Concerning milk. Milk is the only substance which we 

 know to be designed by nature for the sole purpose of supplying 

 nourishment for animal life. For this reason it must always pos- 

 sess a peculiar interest to the student of animal nutrition. It 

 seems reasonable to suppose, from its single purpose, that milk 

 not only contains all the nutrients necessary to sustain the life of 

 young animals but that these are arranged in proper proportion. 



350. Fat and serum. The milk of the cow may be divided into 

 fat and milk serum. The percentage of fat in the milk of the 

 same cow may vary greatly both in the entire milk produced at 

 different periods and in different portions drawn at the same 

 milking. The first milk drawn is poor in fat, while that last 

 drawn is very rich, as is shown by the following table prepared 

 by Babcock of the Wisconsin Station: 1 



Percentage composition of first and last milk from the cow and of the 

 serum Wisconsin Station. 



Bui. 18. 



