240 AGRICULTURE 



Just as a fire needs fuel to keep it going, the animal needs food 

 to keep it alive. Every beat of the heart, every movement of the 

 body, wears out tissue, and the old particles must be replaced by 

 new. This change goes on gradually but so constantly that all 

 particles in the body except, it is believed, the enamel of the 

 teeth are replaced by new particles. This new tissue is formed 

 by nourishment which comes from the food. Protein is a flesh 

 former or tissue builder. It forms muscles, nerve tissue, brains, 

 bone, skin, hair, wool, nails, hoofs, and the solid white substance 

 of the blood. The ash forms ash, giving firmness to bones and 

 teeth. 



Second: Food supplies heat. In summer or winter the tem- 

 perature of the body must be kept at about 98. Body heat is kept 

 up chiefly by carbohydrates. Fats serve the same purpose, one 

 pound of fat being equal in feeding value to two and two fifths 

 pounds of carbohydrates. More of this class of food is required to 

 keep the body at the proper temperature in winter than in summer, 

 in cold countries than in warm ones. In winter people eat more 

 meat, hogs and horses more corn, because these are car bo na'- 

 ceous, or heat-supplying foods. When animals are kept in warm 

 stables in winter, it requires less food to keep up body heat. 



Third: Food supplies force or energy. This also is supplied 

 largely by fats and carbohydrates. Every furrow the horse plows, 

 every pound it pulls, every step an animal takes in exercise or in 

 search of food, requires energy. Horses at hard work require 

 more food than those at light work and much more than those that 

 are idle. Even on larger rations, horses are apt to lose flesh during 

 the hard-working spring season. 



Fourth: Food supplies material for growth and fattening. Fat 

 and carbohydrates, often called fat formers, form fat but do not 

 build up tissue. Young growing animals and animals producing 



