diseases of the digestive organs.

THE FEEDING AND MANAGEMENT OF CATTLE. 447Before passing to the next division of the subject, let us reviewbriefly how animals grow and live. All animals live directly or indirectlyon foods furnished by plants. The plant grows through theunion of chemical compounds taken from the air and soil and broughtup into its structure, through that mysterious principle called life, bythe energy of the sun. The sun pouring its rays day after day in summertime, furnishes the energy which welds the simpler compounds intothe more complex ones of the plant organism. In summer time ouranimals crop the grasses of the fields, and in the fall man gathers plantsand their seeds into barns and storehouses that in winter time he maypass them over to his farm animals for sustenance and growth. Thecompounds in the plant substance are separated in the laboratory ofthe stomach and digestive tract and carried about the body, wherethey are built up into the body tissues or stored up as fat, or they maybe burned up at once if needed to give out energy and warmth. Dr.Armsby has happily used the figureof a coiled spring to illustrate thiswonderful phenomenon. The energy of the sun in summer time windsup the spring in the plant, and when the animal consumes the plantthe spring is unwound and exhibits just as much energy in the unwindingas was used in winding it up.In studying these plant compounds we have divided those whichneed especial attention into three groups, under the heads protein, carbohydrates,and fat. As already shown, the protein compounds arethat portion of the food material which may go to build up the muscularportion of the animal body. Among the list of food articles usedby man rich in protein are the lean part of meat, the white of egg, thecheese of milk, and the gluten of wheat; of stock foods rich in proteinwe have cotton-seed meal, oil meal, pease, wheat bran, clover, andalfalfa hay. The firstgreat use of protein is in building up the muscularportion of the body, but we should not forget that it also gives offheat and energy in being broken down to simpler compounds, and mayalso be converted into fat and stored up in the tissues of the body forfuture use.Since the carbohydrates contain no nitrogen they can not go to buildup the muscular portion of the body, but nevertheless they are ofgreat importance and form the largest part of foods used by our farmanimals. The firstgreat use of carbohydrates is to furnish fuel forwarming the body and enabling it to perform work. Of human foodsrich in carbohydrates we have sugar and starch, both almost chemicallypure, while the grain of wheat and corn are both very rich in carbohydrates.In animal foods corn, oat straw and cornstalks are allrich in carbohydrates. As the protein compounds may be called themuscle-formers, so the carbohydrates may be called the fuel or energygivers of the body. The fats in foods serve the same purpose as thecarbohydrates, but are more potent, giving off more heat in burning.A pound of fat is generally regarded as 2.2 times as valuable as a poundof sugar or starch in food.