
DIGESTIBILITY OF FISH AND POULTRY. P27 
food other than salmon was therefore 11.6, which, subtracted 
from the protein of the total feces, gave 6.1 grams as due to 
the salmon alone. The total protein supplied by the salmon 
was 243.3 grams, and the amount digested (243.3—6.1) was 
237-2 grams. This quantity, divided by 243.3 grams and 
multiplied by 100 gave 97.49 per cent. as the coefficient of 
availability of the protein of salmon alone. ‘The computations 
for fat were, when practicable, made in the same way. 
It will be noted, however, that in several of the experiments 
the coefficient for fat was not computed. In such cases it was 
found that the figure obtained, in the manner outlined above, 
for feces from food other than poultry or fish was larger than 
the amount actually obtained by analysis for the total feces. 
The explanation of this discrepancy is to be found in the 
relatively small amounts of fat found in the feces as compared 
with the amounts supplied in the food. Under such condi- 
tions, a relatively small error in the assumed coefficient may 
make a considerable difference in the calculated result. In 
such cases, it has been assumed that the fat of the fish or 
poultry would have the saine coefficient of availability as the 
total diet. 
Since the poultry and fish contained no carbohydrates, it 
was assumed that the entire carbohydrates of the feces came 
from the remainder of the diet. 
No coefficients of availability of the ash of the poultry and 
fish were computed, as the coefficients of availability of the ash 
of the other materials are not known with sufficient accuracy. 
Coefficients of availability of energy.—'The computations for 
the availability of the energy differ from the corresponding 
computations for the nutrients, in that the former show, not 
the actual availability of the energy to the body, but merely 
the quantity of energy in the food absorbed from the alimen- 
tary canal. It is known that a portion of the protein absorbed 
is not completely oxidized in the body, since it is excreted in 
forms like urea, uric acid, etc., which are capable of further 
oxidation outside the body. Account must therefore be taken 
of the energy lost to the body in these incompletely oxidized 
forms. 
