THE FEED REQUIREMENTS OF FARM ANIMALS 135 



Requirements for Fattening. — Fattening consists of a 

 storage of animal fat in X\\v cells of the various tissues of the 

 body, especially in the tissues of the abdominal cavity and in 

 the connective tissues just under the skin and between the 

 muscles. 



In the practical feeding of animals intended for meat 

 production it is difficult and unnecessary to draw any sharp 

 line between growth and fattening, especially in view of 

 the increasing tendency to fatten and market cattle and 

 hogs before they are mature. It is sufficient to say that 

 if the ration contains a surplus of nutrients above the re- 

 quirements of the animal for maintenance and growth, the 

 surplus up to a certain hmit may be used for the production 

 of fat. 



We have learned that the principal sources of body fat 

 are the carbohydrates and fat of the feed, although any 

 surplus of protein in the ration may serve also for the pro- 

 duction of fat. Consequently, in feeding fattening animals, 

 the amount of protein in the ration is of major importance, 

 while the amount of carbohydrates and fat or of energy is 

 of minor importance, as long as enough of them is supplied. 

 Inasmuch as the most rapid fattening is usually the cheapest 

 fattening, a practical method of formulating the rations of 

 fattening animals is to fulfill the protein requirement and 

 then give them all the carbohydrates and fat they will 

 consume. 



The idea of the amount of protein required for fattening 

 has undergone considerable modification within the last 

 few years. The idea of the older investigators in animal 

 nutrition regarding the production of body fat was that the 

 protein of the feed was its sole source. Consequently, the 



