12 BULLETIN" 751, U. S. DEPARTMENT OE AGRICULTURE. 
Summary of digestion experiments with fine wheat bran in a simple mixed diet. 
Experiment No. 
Subject. 
Digestibility of entire ration. 
Esti- 
mated 
digesti- 
bility 
of pro- 
tein of 
bran 
alone. 
Esti- 
mated 
digesti- 
bility of 
carbohy- 
drate of 
bran 
alone. 
Protein. 
Fat. 
Carbo- 
hydrate. 
Ash. 
417 
418 
419 
420 
460 
461 
462 
463 
D. G. G 
A T TT 
R. L. S 
0. E. S 
D. G. G 
A.J. H 
P. K 
P*. L. S 
Per cent. 
30.9 
17.2 
1.7 
13.7 
61.8 
52.7 
56.8 
60.8 
Per cent. 
93.7 
63.2 
86.7 
85.2 
95.6 
95.7 
93.4 
94.6 
Per cent. 
71.0 
85.1 
66.3 
74.1 
86.2 
85.5 
83.1 
87.0 
Per cent. 
52.0 
37.4 
34.6 
41.6 
71.6 
67.3 
63.5 
70.9 
Per cent. 
18.0 
C 1 ) 
C 1 ) 
0) 
56.8 
43.2 
50.1 
55. 7 
Per cent. 
38.4 
69. 2 
28.8 
37.6 
71.0 
67.5 
65.3 
74.7 
37.0 
88.5 
79.8 
54.9 
44.7 
56.6 
a Negative value, fecal protein exceeding that of bran eaten. Not included in average. 
The subjects ate on an average 32 grams of protein, 134 grams of 
fat, and 265 grams of carbohydrate daily, which taken together fur- 
nished in round numbers 2,400 calories. The diet was somewhat low 
in energy for active young men and decidedly low in protein. With 
the diet followed, a low protein consumption is almost unavoidable, 
for it wa$ hardly possible to eat more of the bran bread than was 
consumed (approximately 420 grams daily), and in order that the 
bran might supply the major portion of the protein intake it was not 
desirable to increase the amount of potato taken with the bread. 
The average coefficients of digestibility of the diet as a whole were 
found to be for protein 37 per cent, for fat 88.5 per cent, and for 
carbohydrate 79.8 per cent. Excluding experiments Nos. 417, 418, 
419, and 420. in which the digestibility of protein was very low, the 
average coefficient of digestibility for protein becomes 58 per cent. 
Excluding experiment No. 417 and leaving out the negative values it 
becomes 51.4 per cent for the protein of bran alone. 
As regards the laxative properties of the diet, records kept by the 
subjects show a variation from " condition entirely normal " to 
"bowels very loose." In three of the experiments, Nos. 418, 419, 
and 420, the amount of bran protein excreted in the feces exceeded 
that supplied by the bran eaten. In these cases, and also in experi- 
ment No. 417, where the digestibility was very low as compared with 
other tests, it might be assumed that an increase of peristalsis has 
effected a greatly decreased absorption, or that for some cause there 
has been an increase in the elimination of metabolic nitrogen through 
the intestines. 
