CHAPTER IV 

 THE COMPOUNDS OF ANIMAL NUTRITION 



The animal body consists primarily of elements, but 

 we ordinarily regard it as made up of compounds. These 

 are groups of elements united in such fixed and con- 

 stant proportions that they have as uniform properties, 

 under given conditions, as the elements themselves. In 

 discussing the composition and uses of cattle foods and 

 the structure, composition, and functions of the animal 

 as an organism, we refer chiefly to the compounds of 

 carbon rather than to carbon itself. In the language of 

 practice, we speak of proteins, carbohydrates, and fats. 

 Commerce recognizes these compounds also. These com- 

 pounds are the som-ce of the energy that is manifested by 

 animal life, and, with the ash, of nearly all the materials 

 out of which animal tissues are built. 



32. The classes of CQmpotuids. — ^The known com- 

 pounds that belong to life in all its forms are almost 

 innumerable. These sustain a variety of relations to 

 human needs, some serving as food, some as medicine, and 

 some in the arts. Comparatively few of these must be 

 considered in discussing the science and art of cattle- 

 feeding. Moreover, the compounds which play a leading 

 part in animal nutrition are designated, especially for 

 practical purposes, in classes rather than singly, which 

 tends to more or less looseness of expression and definition. 

 For instance, the popular understanding of the term pro- 

 tein doubtless is that it is a single compound. 



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