286 PRINCIPLES OF ANIMAL NUTRITION. 
In other words, to get at the actual metabolizable energy of the 
ration in this experiment we must add to the observed potential 
energy of the urine the amount of 46.2 Cals. by which it would have 
been increased had all the protein of the food been metabolized, or, 
what is the same thing, must subtract this amount from the ob- 
served difference between food and excreta. ‘This leaves 16,322.1 
Cals. as the metabolizable energy of 7263 grams of dry matter or 
6750 grams of organic matter in meadow hay, and the metabolizable 
energy per gram of organic matter is therefore 2.418 Cals. 
Computed in the above manner, the several experiments of this 
category gave per day and head the following results: 
q Metabolizable 
| 3 Energy of ierege 
| 2 
iB 3% 
Ani- ‘ 3 a] per 
mal: as =E Urine | meth- ce 
@| Food. | Feces. | (Cor- |°2" | Total;,| 07; 
‘g | Cals. -/ Cals. | rected). or" | Cals.” | Fame 
a Cals. haat oot A Rasta 
‘ to ang oT ter, 
6 Cals. 
32177 .3|11750.3|1991:2 |2113.7|16322- 112.418 
A | Meadow hay I 
I ey ‘A 36975 .1/15524 1/1925 .7*/3137 . 2116388 . 112.097. 
Vv n fe Bins 34211 .5/15312.2/1559 | 3*/2268 .5|15071 5/2093 
VI “ nee 33855 .4|13765 . 2/1737 .9*|2480 .6|15871 .7|2.228 
XX if “ M.: 37167 .3113880 .7/3224.6 12646.1/17415.9'2.230- 
L sh “IL. 32252 .2/14669 .0/1686.9 |2092.3/13804.0)/2.026 
Rica, RTS O AAT aicas epiare [iecornid gute! [e Bavancotee favs Ont are Sarcioe sl wena {2.182 
B | Meadow hay and oat straw. -17107|33794 .4|14576 .1)1440.3 |2331.2/15446.8/2.173 
WI |Clover ° « . .|7328/34603 . 2|15505 . 1/1549 . 6*/2670 114878 .412 031 
IV : ps @ os), ,17074)33405 .1/15250.6/1481 . 5*/2491 .3)14181 . 7/2004 
* Energy of urine computed from its carbon content. 
It should be noted that the figures for the energy of the feces in 
these and in all the succeeding experiments include that of the met- 
abolie products contained in them. While the latter are not derived 
directly from the food they are a part of the expenditure made by 
the body in the digestion of the food, and there is. therefore, the same 
reason for including their energy as for including that of the organic 
matter of the urine. 
Both contain a certain amount of potential energy, derived 
ultimately from the food, which has escaped being metabolized in 
