BUILDING MATERIAL 127 



the production of the lean meat or muscle tissue, and, to 

 a lesser extent, bone tissue of the body. Bones, as is well 

 known, are made up largely of mineral matter. Feeds 

 that contain a considerable quantity of protein are called 

 nitrogenous feeds because nitrogen is the distinguishing 

 element of protein. It must be remembered, however, 

 that nitrogenous feeds in general also contain more or 

 less of the other nutrients. 



For a thorough understanding of the term protein, a 

 further exemplification of the above definition is neces- 

 sary. Total nitrogen compounds (N x 6.25) are called 

 crude protein. This includes all the nitrogen compounds 

 of feeds. Sometimes they are simply called protein for the 

 sake of brevity. True protein, or what is correctly meant 

 when the word protein is used alone, includes only those 

 nitrogenous compounds that can be used for the con- 

 struction of the lean meat or muscle tissue of the body 

 and otherwise to supply the general protein metabolism. 

 Subtracting the true protein, or protein from the crude 

 protein, there is left what is called non-protein. This is 

 also a nitrogenous substance, but cannot be used by the 

 animal body to supply protein metabolism or the purposes 

 for which true protein is used. Protein is present to a 

 greater or less extent in almost all feeds, but is found 

 most abundantly in nitrogenous feeds. 



Carbohydrate. — Carbohydrate nutrients are those used 

 by the animal body for the production of energy; second 

 (during cold seasons or in cold climates), for the produc- 

 tion of heat, and third, for the production of fat. This 

 substance is found in most feeds, but occurs in largest 

 quantities in those classified as carbonaceous. Starches 

 and sugar are popularly used examples of carbohydrate 

 as discussed in stock feeding. 



