CHAPTER III 



THE CHEMICAL ELEMENTS INVOLVED IN 

 ANIMAL NUTRITION 



It is fundamentally necessary, to an intelligent under- 

 standing of the principles and economy of cattle-feeding, 

 to know the kinds and soiu-ces of the materials out of 

 which vegetable and animal tissues are constructed. We 

 are primarily concerned with chemical elements. 



6. Chemical elements involved in animal growth. — 

 Approximately eighty substances are now believed to be 

 chemical elements, i. e., substances that have not been 

 resolved into two or more simpler ones, and of which, so 

 far as is now known, all forms of matter are composed. 

 About one-fifth of these fundamental substances are 

 involved in plant growth, those that occupy a prominent 

 place in animal nutrition being even less in number. 

 These fifteen elements are the following, some of which 

 are of minor importance: carbon, oxygen, hydrogen, 

 nitrogen, sulfur, phosphorus, chlorine, iodine, silicon, 

 fluorine, potassium, sodium, calcium, magnesium, iron, 

 and manganese. 



At ordinary temperatures, four of these, oxygen, 

 hydrogen, nitrogen, and chlorine are gases and the remain- 

 ing ones are solids. Carbon, oxygen, hydrogen, and 

 nitrogen are constant and important ingredients of the 

 atmosphere and they exist in the soil in gases as well as 

 in the various combinations. The other eleven, though 

 sometimes present in the air in minute quantities, are 



(12) 



