THE FOOD AS A SOURCE OF ENERGY. 299 
Periods 4 and 7, the amounts of digestible organic matter in the 
two rations were: 
BOTOG W Aitde aiectaostdcaa Geta barren 7106 grams 
PO@riOd 4, cae sina aieeas else eates 4845 “ 
Difference.................. 2261 “ 
The table shows, however, that in Period 7 the animal received 44 
grams more of total organic matter in the basal ration than in 
Period 4. In the latter period the digestibility of the organic 
matter was found to be 75.7 per cent. Consequently, of the 
excess of 2261 grams of digestible organic matter in Period 7 
44x 0.757 =33 grams may be regarded as derived from the basal 
ration and 2261—33=2228 grams from the meadow hay added. 
The corresponding corrected amounts of energy as given in the 
same table are— 
Total Cots. |, Gin Bigeted 
Cals. 
Energy of added hay (corrected). . a 15728 .6 
“* corresponding feces........... 5471.0 
“_ digested matter.............. 10257 .6 4.604 
Metabolizable energy................... 8504.8 3.817 
The table on the next page contains the results of these com- 
putations expressed per gram of digested organic matter. Kell- 
ner * has made the same comparison in a slightly different man- 
ner. His results for the gross energy of the digested matter are 
given subsequently (p. 310). Those for metabolizable energy do 
not differ materially from those here given. 
CONCENTRATED FEEDING-sTUFFS.—The results of experiments 
upon concentrated feeding-stuffs may of course be computed in the 
same manner as those upon coarse fodders just considered. In the 
case of materials like starch, oil, and gluten, however, which differ 
widely from ordinary feeding-stuffs and which produce material 
and readily traceable effects upon the digestibility of the basal 
ration. relatively little value attaches to computations of the appar- 
ent metabolizable energy, and only the average results with these 
materials have been included in the summary on page 301 for the 
* Loc. cit,, 58, 414 and 447. 
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