DIGESTIBILITY OF SOME ANIMAL FATS. 11 
Summary of digestion experiments with brisket fat in a simple mixed diet. 
Experiment 
No. 
Subject. 
Protein. 
Fat. 
Carbohy- 
drates. 
Ash. 
338 
H. F. B 
Per cent. 
55.6 
64.6 
67.5 
58.9 
49.0 
61.4 
51.5 
Per cent. 
94.1 
94.3 
95.9 
94.3 
89.1 
89.9 
92.2 
Per cent. 
96.9 
96.8 
96.5 
97.1 
94.7 
96.9 
95.8 
Per cent. 
47 .4 
339 
D.G.G 
R.L.S 
O.E.S 
D. G.G 
R.L.S." 
0. E. S 
60.5 
340 
53.3 
341 
50.9 
347 
45.4 
348 
57.1 
349 
51.9 
i 
58.4 
92.8 
96.4 
52.4 
The data of the experiments indicate that the ration supplied 82 
grams of fat daily and that this was 92.8 per cent digested. When 
allowance is made for the small quantity of fat in the basal ration 
and for the metabolic products in the corresponding feces, the digest- 
ibility of brisket fat alone becomes 97.4 per cent. The protein and 
carbohydrate contained in the diet were 58.4 per cent and 96.4 per 
cent digested, respectively. 
It is interesting to note that the brisket fat is somewhat more com- 
pletely assimilated than the kidney fat, of which 93 per cent was 
digested, 1 on an average. Although this difference is not very great, 
it may contribute added evidence to the theory that the properties 
of fats vary with the part of the animal body from which the fats 
are taken. 
CREAM. 
Owing to the pleasant taste and its very general use in the dietary, 
the digestibility of milk fat in the form of cream rather than as a 
separated fat like butter is of particular interest. The question as to 
whether an emulsion or the separated fat is the more thoroughly 
digested has been studied by Wells, 2 who found in the case of cod- 
liver oil that very little difference existed in the digestibility of the 
two forms. In a series of experiments to determine the influence on 
metabolism of an excess of fat in the diet, Atwater 3 found that an 
average of 320 grams of fat daily in a simple mixed diet was 98 per 
cent digested. Approximately 85 per cent of the total quantity of 
fat eaten was furnished by cream and milk. 
The digestibility of butter, as determined in this office in a series of 
eight experiments, was found to be 97 per cent, 4 and in a later series 
of tests, in which the digestibility of the protein of hard palates was 
studied, butter was found to be 95 per cent digested. 5 Due very 
possibly to the belief that milk fat in all its forms is equally available 
to the body, very few similar studies of cream have been reported. 
i U. S. Dept. Agr. Bui. 310 (1915). 
2 Brit. Med. Jour., 2 (1902), No. 2181, pp. 1222-1224. 
3 Connecticut Storrs Sta. Rpt. 1901, pp. 230-233. 
■4 U. S. Dept. Agr. Bui. 310 (1915), p. 21. 
a U. S. Dept. Agr., Jour. Agr. Research, 6 (1916), No. 17, pp. 641-648. 
