12 
BULLETIN 649, U. S. DEPARTMENT OE AGRICULTURE. 
Considering the diet as a whole, 95 grams of protein, 68 grams of 
fat, and 150 grams of carbohydrates were eaten per day, of which 
92.5 per cent of the protein, 95 per cent of the fat, and 97.5 per cent 
of the carbohydrates were digested. The fuel value of the diet was 
1,592 calories. The estimated digestibility of grayfish protein and 
fat as obtained by making allowance for the unutilized protein and 
fat resulting from the accessory foods of the diet are 92.8 per cent 
and 94.3 per cent, respectively. 
The four different subjects who assisted in the eight experiments 
conducted to determine the digestibility of grayfish ate on an average 
440 grams of grayfish daily as compared with 471 grams of butter- 
fish, 448 grams of mackerel, and 355 grams of salmon, which would 
indicate that this fish was eaten with as much relish as the other 
fish studied. 
SALMON. 
Since difficulty was experienced in securing fresh salmon for the 
purpose of this investigation, a good grade of canned salmon (Chinook 
salmon, Oncorhynchus tsch-awytscha) was used instead in the experi- 
ments here reported. The canned salmon was purchased without 
regard to any commercial brand frofn a wholesale grocer, and was 
taken to represent this type of fish in general use. 
The results obtained in three-day test periods with salmon are 
given in the table which follows: 
Data of digestion experiments with salmon in a simple mixed diet. 
Weight 
of food. 
Constituents of foods. 
Experiment, subject, and diet 
Water. 
Protein. 
Fat. 
Carbohy- 
drates. 
Ash. 
Experiment No. 561, subject H. R.. G.: 
Grams. 
1, 004. 
411.0 
297.0 
514.0 
23.0 
Grams. 
621.8 
310.3 
20.5 
434.8 
Grams. 
249.8 
10.3 
24.0 
2.1 
Grams. 
108.8 
0.4 
39.8 
2.6 
Grams. 
Grams. 
23.6 
Potato 
85.9 
210.3 
73.0 
23.0 
4.1 
2.4 
Fruit 
1.5 
2,249.0 
46.0 
1,387.4 
286.2 
23.3 
262.9 
151.6 
4.7 
146.9 
392.2 
13.5 
378. 7 
31.6 
4.5 
27.1 

Per cent utilized 
91.9 
96.9 
96.6 
85.8 
Experiment No. 562, subject A. J. H.: 
854. 
528.9 
212. 5 
92.5 
20.1 
Crackers 
104.0 
103.0 
24.0 
7.2 
87.2 
8.4 
0.4 
14.0 
0.5 
73.6 
14.6 
24.0 
0.8 
Fruit 
0.3 
1, 0S5. 
42.0 
623,3 
221.3 
IS. 3 
203.0 
107.0 
12.1 
94.9 
112.2 
6.7 
105. 5 
21.2 
4.9 
16.3 
Per cent utilized 
91.7 
SS. 7 
94.0 
76.9 
