
FUEL VALUES OF DIGESTED NUTRIENTS. 125 
DIGESTION EXPERIMENT NO. I. 
(See page 109, this Report.) 
Bran, corn meal and hay. 
In this experiment three different feeding stuffs were employed. The compo- 
sition of each was determined by analyses. Their fuel values were determined 
by combustion in the bomb calorimeter, and were also calculated from the chem- 
ical composition. The methods employed for calculating from chemical compo- 
sition are those explained in the Report of this Station for 1890, pages 174-181, 
and are also referred to on page 43 of this Report. The fuel values as obtained 
in the two ways were somewhat different, as appears from the following figures: 
fuel Values—Calories per Gram of Water-free Substance. 





Laboratory | As Calculated from | As Determined by 
No. Analysis. Bomb Calorimeter. 
Bran, e : - - 1301 4.430 4.585 
Corn meal, = - - 1300 4.4600 4.520 
Hay, ee er 1325 4.245 4.515 



The fuel value of the total food eaten in five days was obtained by multiplying 
the number of grams of food by the fuel value per gram as determined by the 
bomb calorimeter. 
Fuel Value of Total Food Eaten in 5 Days, as Determined by Bomb Calorimeter. 
Fuel value of bran, 2 - = - - - 2,360 Calories. 
Fuel value of corn meal, = = = - . 6,725 Calories. 
Fuel value of hay, - - - - - - - 9,345 Calories. 
Total fuel value of food eaten, - = : - 18,430 Calories. 
The feces were burned in the bomb calorimeter. Multiplying the number of 
grams by the fuel value of one gram gives the figures which follow: 
Sheep B, - - - - - - - - 7,600 Calories. 
Sheep D, - - - - - - - ~ 5,920 Calories. 
When protein is burned in the calorimeter it is completely oxidized, the carbon 
being burned to carbon dioxide and the hydrogen to water. The nitrogen is 
left uncombined. When protein is consumed in the body the oxidation is not 
complete. The nitrogen is left in urea, uric acid and other allied compounds, 
all of which contain carbon and hydrogen, together with some oxygen. In 
estimating the actual fuel value of the digested ingredients which an animal can 
utilize, allowance must be made for these unconsumed residual products, which 
are excreted by the kidneys. Urea is usually the most abundant of these 
excretory products, and it is here assumed that all of the nitrogen of the digested 
protein is excreted as urea. The fuel value of urea as determined by Stohmann 
and Berthelot is 2.53 Calories per gram.* } 
The method used in the calculations here has been as follows: Urea 
(CONz2 H,) contains 46.67 per cent. of nitrogen. Hence nitrogen multiplied by 
the factor 2.143 equals urea. ‘The protein as here estimated is the nitrogen 

* See Bulletin No. 21 of the Office of Experiment Stations, U.S. Department of Agriculture, 
on Methods and Results of Investigations of the Chemistry and Economy of Food, for a more 
detailed discussion of the subject. 
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