12 The Bulletin. 



Food-stuff. { {5^.^*^j;- fAsh. (Protein. 



I U.y Matter. | ^^.^^^.^ ^^^^^^^,_ P^^^^ Nitrogen free Ex't 



Icarbohydrates. {gjtroge^n^^^^^^ 



Nutrients. — Protein, fats, carbohydrates, nitrogen-free extract and 

 cinide fiber and mineral matter are called nutrients because of their 

 functions in animal nutrition. Nitrogen-free extract and crude fiber 

 are included together under the one name of carbohydrates, because 

 they are all compounds of carbon, hydrogen and oxygen, and the 

 digestible portion of each is considered of equal value and perform 

 the same offices in animal nutrition. Familiar examples of the 

 four classes of nutrients are presented below. "Water is omitted 

 because it is the same whether taken in food or drink, and we do not 

 feed a fodder for the sake of the water it contains. 



C Albumen (white of egg), washed lean meat, casein, or 

 Protein. . <j curd of Milk, gluten of flour, fibrin of blood, gelatin, 

 ( curd, etc. 



C Cotton-seed oil, linseed oil, olive oil, corn oil, wheat oil, 

 J oat oil; the fat of milk (butter), the fat of meat, hog 



^1 (lard), mutton (mutton suet), beef (tallow), fish oil, 



(^ etc. 



Carbohy- f Sugars (cane sugar, milk sugar, and glucose), starch, 

 drates. \ dextrin, gums, woody fiber, etc. 



Mineral / Sodium chloride (common salt), ])hosphates of lime and 

 Matter. \ soda, etc. 



Functions of Nutrients. 



Having discussed the classes of nutrients as they occur in foods, 

 the question may be asked : What offices do these nutrients perform 

 in the animal economy ^ 



Water is not a nutrient in the sense in which the term is here used, 

 though the animal body cannot be sup])orted without it. 



Tlie ash, or mineral matter, furnishes the material for the bony 

 structure of the body, and, to a far less extent, of the soft tissues. 

 Most of our foods and rations contain an abundant supply of the 

 mineral elements, so little or no notice need be taken of them in 

 feeding. 



Protein differs from all the other nutrients in containing the ele- 

 ment nitrogen, and is the producer of flesh, ligaments, muscles, ten- 

 dons, sinews, hair, hide and all portions of the animal machine 

 which have strength, except the bones. The ]irotein bodies are of 

 the utmost importance in the animal structure. They compose the 

 larger part of the animal machinery, and are the exclusive source 

 of its repair as occasioned by the continuous wear and tear of the 

 system, due to the internal and external movements of the body; 



