COMPOSITION OP FEEDING STUFFS. 213 



remains behind when the body is burned. The bones of animals 

 contain large quantities of mineral matter, while the muscles and 

 other parts of the body contain only small amounts; it must not 

 be concluded, however, that the ash materials are of minor impor- 

 tance for this reason; both young and full-grown animals require 

 a constant supply of ash materials in their food; if the food should 

 not contain a certain minimum amount of ash materials, and of 

 various compounds contained therein which are essential to life, 

 the animal will very soon turn sick, and if the deficiency is not 

 made up will die, no matter how much of other food components 

 may be supplied. As both ash and water are either present in 

 sufficient quantities in feeding stuffs, or can be easily supplied, the 

 feeder does not ordinarily need to give much thought to these 

 components in the selection of foods for his stock except in the 

 case of young animals fed corn (which is lacking in ash ma- 

 terials), and in feeding milch cows and steers which require an ad- 

 dition of salt in order to do well. 



Protein is the name of a large group of very complex substances 

 that have certain characteristics in common, the more important 

 of which is that they all contain the element nitrogen. The most 

 important protein substances found in the animal body are: lean 

 meat, fibrin, all kinds of tendons, ligaments, nerves, skin, brain, in 

 fact the entire working machinery of the animal body. The casein 

 of milk and the white of the egg are, furthermore, protein sub- 

 stances. It is evident from the enumeration made that protein is 

 to the animal body what the word implies, the most important, 

 the first. 



Fat is a familiar component of the animal body; it is dis- 

 tributed throughout the body in ordinary cases, but is found de- 

 posited on certain organs, or under the skin, in thick layers, in the 

 case of very fat animals. 



The animal cannot, as is well known, live on air; it must manu- 

 facture its body substances and products from the food it eats, 

 hence the next subject for consideration should be: 



Composition of Feeding Stuffs. 



The feeding stuffs used for the nutrition of our farm animals 

 are, generally speaking, composed of similar compounds as those 



