BREEDS OF BEEF CATTLE 



291 



stance called glycogen, belonging to the group of carbohydrates de- 

 scribed in the next section. Neither fat nor glycogen contains the 

 elements nitrogen or sulphur, but each is composed entirely of carbon, 

 hydrogen, and oxygen. 



Composition of the Entire Body. The average results of an- 

 alyses shown in the following table indicate the composition of the 

 bodies of different animals in different conditions: 



Percentage Composition of Live Animals. 



Components of Feeding Stuffs. Like the animal body, the vege- 

 table feeding stuffs which nourish it contain a great variety of sub- 

 stances, but these, too, like those of the animal, may be classified into 

 a few groups. Not only so, but these main groups are the same as 

 those found in the animal, viz, water, ash, protein, fats, and carbo- 

 hydrates. The proportions of these ingredients in the animal body 

 and in vegetable substances, however, are widely different. 



Protein and Fat. Protein is the predominant ingredient, aside 

 from water, in the animal body, while the latter stores up its reserve 

 material in the form of fat with but little carbohydrates (glycogen). 

 Protein is also contained in all plants and, as in the animal, forms 

 the basis of the living tissues, but the predominant ingredients as 

 regards quantity are the carbohydrates. In the form of cellulose, or 

 crude fiber, they form the cell-walls of the plant, while as starch and 

 sugar they are stored up in large amounts in the cells of seeds and 

 roots as reserve material. A few plants, like flax and cotton, store up 

 oil instead of starch and are likewise rich in protein, but as a rule the 

 common feeding stuffs contain relatively small amounts of protein 

 and fat and are rich in carbohydrates. 



The protein and fats of plants are not widely different from 

 those of animals and call for no special description here. 



Carbohydrates. The carbohydrates, as starch, sugar, etc., con- 

 stitute a distinct group, represented in the animal chiefly by the small 

 amounts of glycogen mentioned previously and by the sugar of the 

 milk. They are composed of the chemical elements, carbon, hydro- 

 gen, and oxygen, the two latter being present in exactly the same 

 relative amounts as in water, Like the fats, they contain no nitrogen 



