UNITED STATES DEPARTMENT OF AGRICULTURE 
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BULLETIN No. 310 
Contribution from the States Relations Service 
A. C. TRUE, Director 
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Washington, D. C. 
PROFESSIONAL PAPER 
November 9, 1915 
DIGESTIBILITY OF SOME ANIMAL FATS. 
By C. F. Langworthy, Chief, and A. D. Holmes, Scientific Assistant, Office of Home 
Economics. 
CONTENTS. 
Page. 
Introduction 1 
Nature of the diet 2 
Experimental methods 4 
Page 
Digestion experiments— Lard, beef fat, mut- 
ton fat, butter 5 
General discussion 20 
INTRODUCTION. 
Notwithstanding the fact that fats are ordinarily one of the prin- 
cipal sources of energy in the diet and are two and one-fourth times 
as effective for this purpose as either protein or carbohydrates, their 
use in the diet has received less attention by investigators, and is 
consequently less perfectly understood than that of other nutrients. 
It has generally been taken for granted that when eaten in favorable 
combinations fats are thoroughly assimilated and that the different 
kinds do not vary enough in this respect to affect materially the 
amount of energy which the body derives from them. The recorded 
experimental data, however, are not conclusive on this point. Ex- 
perimental data are also very limited on another point which is a 
matter of particular interest at the present time, when the increased 
demand for culinary and table fats tends to bring into the market 
kinds which have hitherto been used little if at all, namely, the rela- 
tion of melting point to thoroughness of digestion, particularly with 
respect to fats of high melting point. 
It is true that many digestion experiments have been carried on 
with food materials such as milk, cheese, meat, etc., which contain 
much fat, but relatively few dealing directly with culinary and table 
fats have been reported and only a small proportion of these have been 
made under comparable conditions, and while it is also true that the 
melting point of fats has been very generally and accurately deter- 
Note.— This bulletin records studies of the digestibility and melting point of lard, beef fat, mutton fat, 
and butter, and is primarily of interest to students and investigators of food problems, 
8829°— Bull. 310—15 1 
