12 BULLETIN 613, U. S. DEPARTMENT OF AGRICULTURE. 
Summary of digestion experiments with horse fat in a simple mixed diet. 
Subject. 
Digestibility of entire ration. 
Esti- 
mated 
Experiment No. 
Protein. 
Fat. 
Carbohy- 
drate. 
Ash. 
digesti- 
bility of 
horse fat 
alone. 
747 
P.K 
Per cent. 
67.8 
58.5 
55.0 
Per cent. 
95.0 
93.3 
92.4 
Per cent. 
97.6 
95.8 
95.4 
Per cent. 
74.5 
59.2 
58.5 
Per cent. 
95.2 
748 
M.L. M 
93.7 
749.. . 
J. C. M 
92.7 
60.4 
93.6 
96.3 
64.1 03 
The fat-rich blancmange containing horse fat formed the predomi- 
nating part of a simple mixed diet and was eaten without comment, 
indicating that this blancmange was as acceptable as that served in 
other experiments of a similar nature. All the subjects stated, in the 
reports which they submitted regarding their physical condition dur- 
ing the experimental period, that they continued in normal health. 
On an average the subjects ate 28 grams of protein, 65 grams of 
fat, and 462 grams of carbohydrate daily, which supplied 2,545 calo- 
ries of energy. The coefficients of digestibility of the diet as a whole 
were for protein 60.4 per cent, for fat, 93.6 per cent, and for the 
carbohydrate 96.3 per cent. If correction for the metabolic products 
and undigested basal ration fat is applied to the figure 93.6 per cent, 
the digestibility of the total fat of the diet, it is found that the coeffi- 
cient of digestibility of horse fat alone is 93.9 per cent. This figure, 
93.9 per cent, is for dietetic purposes the same as 93 per cent re- 
ported 1 in an earlier paper for the digestibility of beef -kidney fat. 
It is higher than the digestibility reported from similar experiments 
with mutton-kidney fat 1 (88 per cent) , and somewhat lower than the 
digestibility of lard 1 (97 per cent), butter 1 (97 per cent), and beef- 
brisket fat 2 (97.4 per cent). 
On the basis of these experiments it appears that rendered horse 
fat obtained from healthy animals when eaten as a part of a simple 
mixed diet in amounts not exceeding 65 grams daily produces no 
physiological disturbances and was well utilized by the human body. 
OLEO OIL. 
Beef tallow, like other edible fats, consists essentially of olein, 
palmitin, and stearin. In order to utilize most efficiently the enor- 
mous quantities of beef tallow that result from the slaughter of cattle 
in this country yearly, it has been found satisfactory to separate 
the beef tallow into soft (oleo oil) and hard (oleo stearin) fats. The 
1 U. S. Dept. Agr. Bui. 310 (1915), p. 21. 
2 U. S. Dept. Agr. Bui. 507 (1917), p. 18. 
