140 FIRST PRINCIPLES OF AGRICULTURE. 



The composition of horny matter is quite uniform, and 

 is similar to albumen in content of nitrogen, though con- 

 taining more sulphur. 



Inorganic Matter or Ash. The ash constitutes a 

 very small part of the total weight of animals. It ranges 

 from one and eight-tenths per cent to three per cent in 

 swine, and from four and five-tenths per cent to five 

 per cent in cattle. The ash constituents are greatest in 

 lean animals, and least in fat animals. Of the different 

 parts of animals, the dried bones contain the largest 

 portions, reaching fifty per cent in the bones of young 

 animals, and as high as eighty-five per cent in mature 

 animals. Bone-ash consists almost entirely of phosphate 

 of lime. Other very important constituents of the ash 

 are potash, soda, and chlorine. 



Animal Pood. The animal body, consisting of the 

 two classes of substances, the nitrogenous and non-nitro- 

 genous, demands the same classes from the food. These 

 latter correspond in kind to those described as contained 

 in the animal body, with the addition of carbohydrates ; 

 viz., 1. Albuminoids ; 2. Fats ; 3. Carbohydrates ; 4. Min- 

 eral Salts. 



Albuminoids. The albuminoids of a feed include 

 vegetable albumen and fibrin, as well as other substances 

 which resemble in composition the albuminoids of the 

 animal body. The term " protein " is frequently used 

 to designate this class of substances when contained in 

 food. 



The various albuminoids vary somewhat in their com- 

 position. They are distinguished by their high and quite 

 uniform content of nitrogen ; and, though differences exist 



