18 BULLETIN 507,, U. S. DEPARTMENT OE AGRICULTURE. 
Data of digestion experiments icith Boston mackerel in a simple mixed diet — Continued. 
Weight. Water. J^jj" j Fat. 
Carbo- 
hydrates. 
Ash. 
Experiment No. 447, subject 0. E. S.: 
Boston mackerel (in form of fish loaf) 
Grams. 
1. 348. 
476.0 
171.0 
1 ; 594. 
16.5. 
Grams. 
834.4 
Grams. 
291.0 
Grams. 
180.1 
22^9 
8.0 
Grams. 
Grams. 
42 5 
Potato 
Crackers 
Fruit 
3-59. 4 
11.8 
1, 348. 5 
11.9 
13.8 
fi.4 
99.5 
121.1 
226.3 
165.0 
4.7 
1.4 
4 8 
Sugar 
Total food consumed 
3, 7-54. 
70.0 
2, 554. 1 
323.1 
28.6 
294.5 
211.5 
12.2 
199.3 
611.9 
21.6 
590.3 
53.4 
7 6 
45 8 
91.1 
94.2 
96.5 
8-5 8 
Average food consumed per subject per day 
1, 172. 5 
781.5 
108.0 
72.7 
192.9 
17.4 
Summary of digestion experiments — Digestibility of nutrients of entire diet. 
Experi- 
ment Xo. 
Subject. 
Protein. 
Fat. 
Carbohy- 
drates. 
Ash. 
444 
44o 
447 
D. G. G.. 
R. L. S.. 
O.E.S.. 
Per cent. 
94.7 
92.4 
91.1 
Average. 
92. 
Per cent. 
95.9 
96.2 
94.2 
Per cent. 
95.1 
96.6 
96.5 
Per cent. 
90.1 
85.8 
95.4 
>. 1 
As the tables show, the experimental diet supplied, on an average, 
108 grams protein, 73 grams fat, and 193 grams carbohydrates per day. 
The coefficients of digestibility of the entire diet were: Protein, 92.7 
per cent; fat, 95.4 per cent; and carbohydrates, 96.1 percent. 
The amount of fat supplied by other foods than fish was only 17.7 
per cent of the total fat of the diet. Making due allowance for this 
small amount of fat other than fish fat made no significant change, the 
corrected value being 95.2 per cent as compared with 95.4 per cent. 
This is comparable with the values obtained for other fats of similar 
physical characteristics and indicates that, like them, fish fat is well 
assimilated. 
SUMMARY. 
The fats studied in this investigation were well digested, the coeffi- 
cients of digestibility, with allowance for metabolic products and any 
undigested fat supplied by the basal ration, being, for chicken fat, 
96.7 per cent; for goose fat, 95.2 per cent; for brisket fat, 97.4 per 
cent; for butter fat in the form of cream, 96.9 percent; for the fat in 
egg yolk, 93.8 per cent; and for the fat in fish flesh, 95.2 per cent. 
On an average, 95 grams of chicken fat, 95 grams of goose fat, 80 
grams of brisket fat, 78 grams of butter fat in the form of cream, 83 
grams of egg-yolk fat, and 60 grams of fish fat were eaten per subject 
per day. In the case of goose fat, the feces were noticeably soft and 
occasionally a more decided laxative effect was noted, indicating that 
the limit of tolerance for this fat was not far above the 95 grams 
