THE RATIONAL FEEDING OF DAIRY STOCK 133 



crops it ranges from 2 to 4 per cent. The ash is 

 composed of lime, potash, phosphates, and other 

 mineral substances. All of the coarse fodders, grains, 

 and mill products contain a sufficient amount of 

 mineral matter for purposes of nutrition, including 

 phosphates for bone formation and for the production 

 of milk. 



126. The Organic Matter. — That portion of the 

 dry matter which is burned and converted into vola- 

 tile products is called the organic matter. It is 

 obtained by subtracting the per cent of ash from 

 100, which represents the total amount of dry 

 substance. 



127. Proteids. — These compounds, which are found 

 in variable amounts in all food stuffs, are similar in 

 general composition to the milk proteids described 

 in section 82. The proteids as a class are character- 

 ized by containing the element nitrogen in addition 

 to carbon, hydrogen, and oxygen, which are present 

 in all the other nutrients of food stuffs. It is the 

 proteids which serve the special purpose of supplying 

 the materials for repairing the body waste. Proteids 

 are the principal materials out of which the muscles 

 are formed, and they also enter largely into the 

 composition of all the tissues of the body. All the 

 vital fluids of the body, as the blood, contain large 

 amounts of this class of compounds. The proteids 

 of the body can be formed only from the proteids of 

 the food; hence the importance of the requisite 

 supply of this nutrient in the food. An excessive 



