JOMAL OF AGRlfllLTHRAL BESEABOB 
Vol. IX Washington, D. C., June; i8, 1917 No. 12 
A STUDY OF METHODS OF ESTIMATION OF METABOLIC 
NITROGEN 
By E. B. Forbhs, C. E. Mangbls, and L. E. Morgan, 
Ohio Agricultural Experiment Station 
INTRODUCTION 
The so-called metabolic nitrogen of the feces is that portion which has 
an origin other than as an undigested food residue. It consists of resi¬ 
dues from the bile and digestive juices, of epithelium and mucus from 
the digestive tract, and of such products of bacterial activity as have 
been derived from digested or from digestible nitrogen. 
Our reason for wishing to estimate this fraction of the nitrogen of the 
feces is that it is a factor which must be considered in the determination 
of the digestibility of protein—a matter of great importance in relation 
to practical animal and human nutrition. 
The plan of this experiment was to feed a basal ration of corn alone to 
each of five pigs during the first period, and to add to this corn ration in 
subsequent periods nitrogenous supplements to be used in the compari¬ 
son of methods. In the selection of these supplements it was our object 
to choose foods the protein of which would probably be entirely digestible. 
Those used were milk, blood albumen, and commercial dried egg 
albumen. 
In the comparison of methods of metabolic-nitrogen estimation it was 
our object to determine which procedure would yield results representing 
these assumedly entirely digestible protein foods as being entirely 
•digestible—that is, assuming the proteins of milk, for instance, to be 
entirely digestible, we made an effort to determine which method of 
estimation of metabolic nitrogen would assign to the protein of milk a. 
digestion coefficient nearest to 100 per cent. 
An experimental study involving so much assumption can not yield 
results of the highest value, but it was our hope that it might assist in 
the establishment of a useful conventional procedure. 
Journal of Agriculture Research, 
Washington, D. C. 
Vol. IX, No. 1a 
June 18, 1917 
