184 The Feeding of Animals 



formation of animal fats from starch and sugar. Pro- 

 tein is used to construct muscular tissue, in fact, all 

 the nitrogenous parts, and it is perhaps a source of 

 fat. Carbohydrates can only be used constructively 

 for the formation of fat, and the same is true of food 

 fats or oils. Mineral matter is needed for the forma- 

 tion of bone and has important functions in digestion. 



5. The matter of the digested food, including water 

 and oxygen, is exactly equal to that stored in the body 

 or in milk, or both, plus that in waste products, — feces, 

 water, carbonic acid and urine solids. Such a balance 

 may not be maintained for any particular day, but will 

 ultimately be found to exist. 



6. Under given conditions of species, sex, climate 

 and use, a definite amount of digested organic matter 

 is necessary to maintain a particular animal without 

 gain or loss of body substance. This means simply 

 that tissue wastes must be replaced, and the fuel sup- 

 ply must be kept up. 



If the animal receives no food, or less than the 

 amount needed for maintenance purposes, tissue waste 

 and the production of energ}^ do not cease, but go 

 on wholly or in part at the expense of the body sub- 

 stance, and, as it is commonly expressed, the animal 

 "grows thin." 



7. Food supplied above a needed maintenance quan- 

 tity may be utilized for the production of new sub- 

 stances or work or may be eliminated in part and increase 

 the waste. Within limits, both things generallj' occur. 

 In the proper sense of the term, no production ever 

 occurs without an excess of food above the mainte- 



