CHAPTER XXI. 



MAINTENANCE RATION AND FATTENING. 



Maintenance Ration. The amount of food required to main- 

 tain an animal is called the maintenance ration* A maintenance 

 ration must provide enough energy to keep up the body heat, and 

 to supply the digestive and vital processes, and enough proteids 

 to replace the body waste, and provide for natural growth of 

 hair, horn, etc. The amount of body heat required will depend 

 upon the surrounding temperature. At about 33 C. none will 

 be required; the amount necessary at lower temperatures will 

 depend upon the size and shape of the animal, its protective 

 coverings, the quantity and temperature of the drinking water, 

 etc. 



Value of Food for Maintenance. The quantity of body sub- 

 stance protected by given amount of food may be estimated as 

 follows : 



Determine the income and outgo of carbon and nitrogen of the 

 starving animal. Feed the nutrient to be tested, and again deter- 

 mine income and outgo of the carbon and nitrogen. The 

 amount of body fat and flesh protected by the known amount of 

 nutrients fed is thus ascertained. 



For example, the following is an experiment of Rubner: 2 



The meat fed increased the elimination of nitrogen and de- 

 creased the destruction of fat. 



The meat equivalent to 17.47 grams of nitrogen ( = 113.4 



1 Armsby, Bulletin No. 42, Pennsylvania Station. 



2 Zeitsch f. Biol., 1886, p. 04. 



