THE FEEDIXG AND MANAGEMENT OF CATTLE. 447 



Before passing to the next division of the subject, let us review 

 briefly how animals grow and live. All animals live directly or indi- 

 rectly on foods furnished by plants. The plant grows through the 

 union of chemical compounds taken from the air and soil and brought 

 tip into its structure, through that mysterious principle called life, by 

 the energy of the sun. The sun pouring its rays day after day in sum- 

 mer time, furnishes the energy which welds the simpler compounds into 

 the more complex ones of the plant organism. In summer time our 

 animals crop the grasses of the fields, and in the fall man gathers plants 

 and their seeds into barns and storehouses that in winter time he may 

 pass them over to his farm animals for sustenance and growth. The 

 compounds in the plant substance are separated in the laboratory of 

 the stomach and digestive tract and carried about the body, where 

 they are built up into the body tissues or stored up as fat, or they may 

 be burned up at once if needed to give out energy and warmth. Dr. 

 Armsby has happily used the figure of a coiled spring to illustrate this 

 wonderful phenomenon. The energy of the sun in summer time winds 

 up the spring in the plant, and when the animal consumes the plant 

 the spring is unwound and exhibits just as much energy in the unwind- 

 ing as was used in winding it up. 



In studying these plant compounds we have divided those which 

 need especial attention into three groups, under the heads protein, car- 

 l>ohydrates, and fat. As already shown, the protein compounds are 

 that portion of the food material which may go to build up the mus- 

 cular portion of the animal body. Among the list of food articles used 

 by man rich in protein are the lean part of meat, the white of egg, the 

 cheese of inilk, and the gluten of wheat; of stock foods rich in pro- 

 tein we have cotton-seed meal, oil meal, pease, wheat bran, clover, and 

 alfalfa hay. The first great use of protein is in building up the muscu- 

 lar portion of the body, but we should not forget that it also gives off 

 heat and energy in being broken down to simpler compounds, and may 

 also be converted into fat and stored up in the tissues of the body for 

 future use. 



Since the carbohydrates contain no nitrogen they can not go to build 

 up the muscular portion of the body, but nevertheless they are of 

 great importance and form the largest part of foods used by our farm 

 animals. The first great use of carbohydrates is to furnish fuel for 

 warming the body and enabling it to perform work. Of human foods 

 rich in carbohydrates we have sugar and starch, both almost chemi- 

 cally pure, while the grain of wheat and corn are both very rich in car- 

 bohydrates. In animal foods corn, oat straw and cornstalks are all 

 rich iu carbohydrates. As the protein compounds may be called the 

 muscle-formers, so the carbohydrates may be called the fuel or energy 

 givers of the body. The fats in foods serve the same purpose as the 

 carbohydrates, but are more potent, giving ofl' more he.it in burning. 

 A pound of fat is generally regarded as 2.2 times ;w valuable as a pound 

 Of sugar or starch in food. 



