54° PRINCIPLES OF ANIMAL NUTRITION. 
at 4.1 Cals. per gram. As we have seen, however (Chapter X), 
this figure is probably too high for herbivora, although exact figures 
for the horse are not yet fully available. Approximately, however, 
we may estimate the metabolizable energy of the several digested 
nutrients as follows (p. 332): 
Proteins, cia savas eee 3.228 Cals per gram 
Crude fiber. .......... eee eee Beo23.0 ee oy ae 
Nitrogen-free extract.......... 4.185 “ “ << 
Ether extract............00055 8.572 “" « « 
Zuntz * estimates the metabolizable energy of the total nutri- 
ents (including fat X 2.4) at 3.96 Cals. per gram. This figure is 
probably somewhat high, especially for rations containing much 
crude fiber or ether extract, but may serve the purpose of approxi- 
mate calculations. 
EXPERIMENTS ON SINGLE FEEDING-sSTUFFS.—Comparatively few 
of the experiments admit of a direct computation of the utiliza- 
tion for a single feeding-stuff, since in most cases the amounts of 
two or more feeding-stuffs were varied simultaneously. As an 
example of the former class we may take Periods I and II of the 
experiments of 1892-93. In Period I the ration consisted of 7.5 kgs. 
of hay and 4 kgs. of oats per day, while in Period II the oats were 
increased to 5.5 kgs. The quantities of nutrients digested and the 
metabolizable energy of the difference between the two rations 
(computed by the use of the factors just given) were— 
. Crude Nitrogen- Ether Total 
Protein, = fi : 
Girma,” | Gar | xtract, | “meh | Nements 
Period IT....... 1022.4 849.6 4152.8 175.8 6446.6 
PE NM kine ua es 847.8 . 819.9 3598 .4 137.1 5595.3 
Difference .... 174.6 29.7 554.4 38.7 851.3 
: Cals. Cals. Cals. Cals, Cals, 
Equiv. energy... 564 105 2320 332 3321 
In Period I (20 days) the daily work consisted of 300 revolutions 
of the dynamometer. With this amount of work the live weight 
of the horse underwent very little change, but there was a material 
* Landw. Jahrb., 27, Supp. ITI, 418. 
