50 



FARMER'S CYCLOPEDIA OF LIVE STOCK 



NECESSITY FOR FOOD 



Without food the animal dies. No 

 matter whether animals work or rest, 

 whether awake or asleep, certain internal 

 work and changes are constantly going 

 on as long as life lasts. The heart beats, 

 respiration goes on, the body is kept 

 warm. To maintain these vital proc- 

 esses, food is necessary. The body re- 

 quires the tissue building material and 

 the latent energy and heat which is 

 stored in food to maintain it. 



Use of food — After foods have been 

 eaten and acted upon by the digestive 

 juices, the various nutrients which they 



DIGESTIBILITY OF FEEDING 

 STUFFS 



Most of the compounds contained in 

 feeding stuffs must undergo certain 

 chemical changes and modifications be- 

 fore they can be made use of by the ani- 

 mal body. These chemical changes are 

 brought about during the processes of 

 digestion, as was shown in the discussion 

 of the physiology of animals in Part I 

 of this work. Not all the constituents 

 of a feeding stuff, as shown by analyses, 

 are digested. A part passes through the 

 animal undigested. 



In order, therefore, to estimate the 



Fig. 32 — CRIMSON CLOVER AS GROWN IN DELAWARE 



contain are absorbed from the digestive 

 tract and carried by the blood to every 

 portion of the body. Every cell is 

 reached and supplied with the nutriment 

 necessary for its maintenance while the 

 material which the cell has already 

 used is carried away in the blood and ex- 

 creted from the body. The broken down 

 protein is excreted partially in the form 

 of urea from the kidneys through the 

 urine, while the carbon is excreted from 

 the lungs, in the form of carbonic acid 

 through the breath. 



feeding value of any material it is nec- 

 essary to know what portion of the pro- 

 tein, the carbohydates, the fats, etc, con- 

 tained in the feeding stuff is actually 

 digestible. Experiments to determine 

 this matter have been carried on now for 

 many years with different kinds of ani- 

 mals and with all the more usual feed- 

 ing stuffs. The results secured for all the 

 more usual American feeding stuffs are 

 shown in the table on another page, en- 

 titled, The average digestibility of Amer- 

 ican feeding stuffs. Attention will be 



