28 PRINCIPLES OF ANIMAL NUTRITION. 
Henneberg * found that from 26.7 to 30.0 per cent. of the organic 
matter of sheep urine was neither urea nor hippuric acid, while from 
95 to 100 per cent. of the total nitrogen was contained in these two 
substances. G. Kiihn in his extensive respiration experiments on 
oxen, as reported by Kellner,t assuming that all the nitrogen of 
the urine was in the form either of hippuric acid or urea, found that 
from 40.05 to 67.64 per cent. of the total carbon of the urine was 
present in non-nitrogenous substances. The more recent investi- 
gations of Kellner,{ as well as those of Jordan § and of the writer,|| 
have fully confirmed this fact. 
Apparently these non-nitrogenous organic substances are de- 
rived in some way largely from the coarse fodders. Their propor- 
tion in the urine is relatively large when the ration consists exclu- 
sively of coarse fodder, and the addition of such fodders to a basal 
ration causes a marked increase in their amount; while, on the 
other hand, such concentrated feeding-stuffs as have been inves- 
tigated do not produce this effect in any very marked degree. 
Furthermore, their amount seems to bear no fixed relation to the 
protein of the coarse fodder. When the amount of the latter 
ingredient is small, the total organic matter of the urine has in 
some cases exceeded the maximum amount that could have been 
derived from the protein of the food, thus demonstrating that a 
portion at least of the non-nitrogenous urinary constituents must 
have had some other source. As the proportion of protein in the 
food increases, the amount of nitrogenous products in the urine 
likewise increases, while that of the non-nitrogenous products 
appears to be more constant, so that the ratio of urinary nitrogen 
to carbon increases. The most plausible explanation of these facts 
seems to be that the substances in question are derived from some of 
the non-nitrogenous ingredients of the coarse fodders, but from what 
ones, or what is the nature of the products, we are still ignorant. 
* Neue Beitriige, etc., p. 119. 
+ Landw. Vers. Stat., 44, 348, 404, 474, 529. 
tIbid., 47, 275; 50, 245; 53, 1. 
§ New York State Expt. Station, Bull. 197, p. 27. 
|| Penna. Expt. Station, Bull. 42, p. 150. 
q A further discussion of this subject in its relations to the energy of 
the food will be found in Part II. 
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