THE RESPIRATION CALORIMETER. 



1049 



The net results in these two periods, then, may he summarized as 



f()Ih)\vs: 



Balance of nutrienU. 



I'roteifis dig-csted 



Total (irifiiuir matter ilij: 



I'rotein hist bv body 



Put lo.st by body 



Period A. 



Grams. 



146. 8 



1,831.1 



49.2 



259. 



Period B. 



Grams. 



173.2 



2, 539. 7 



7.2 



80.6 



In otlier words, the increase of TOS.C) u-rams in the oroanic matter 

 digested in Period B took the place of 42.0 gi-ams of body protein and 

 ITS. 4 grams of bod}- fat oxidized on the lighter ration; that is, these 

 latter lignres represent the contribution which the added ha}^ made to 

 the maintenance of the body. 



Still another method of comparison is afforded when we turn from 

 considering the food as a supply of matter and regard it as the source 

 of energy to the vital machinery. 



The potential energ}" of feed and of visible excreta is measured by 

 their heats of combustion, which are readily determined ])y means 

 of the bomb calorimeter. The production of heat by the animal is 

 determined directly by the respiration calorimeter. Adding to these 

 data the heat of coml)ustion of the methane excreted, which is readil}" 

 computed from its amount, we have all the data for the construction 

 of a balance of energy similar to the balance of matter. In the two 

 cases selected as examples this was: 



Balance of energy. 



Period A. 



Income. Outgo 



Period B. 



Income. Outgo 



Energy of hay 



Energy of lin.seud meal 



Energy of feces 



Energy of urine 



Energy of methane 



Energy of hair, etc 



Energy of heat produced by steer. 

 Loss of energy by steer 



Calories.a 



13, 035 



1,824 



Calories.a 



Calories.a 



Calories.a 



2,713 



8,574 



965 



1,253 



88 



10, 296 



Total. 



17,572 



17,572 



21, 176 



"The calorie here used is the large calorie (kilogram-calorie), usually written with a capital C. 



In Period A, out of a total of 14,859 calories of energy in the food 

 8,3.57 calories reappeared as unused potential energy in the various 

 excreta. The remainder, 6,502 calories, was used to support the vital 

 activities of the bod}-, and these required in addition 2,713 calories of 

 energy, which was supplied by the oxidation of body tissue. The 49.2 

 grams of protein lost ])y the body would suppl}" for this purpose 280 

 calories and the 259 grams of fat 2,4'61 calories, or a total of 2,741 

 calories, which is practically the same as the amount computed from 

 the energy balance. 



