Dec. 1,1925 
The Maintenance Requirement of Dry Cows 
1067 
THE BALANCE OF MATTER 
From the data in the preceding tables the balance of matter per 
day and head has been computed as recorded in Table XII. The 
balance of matter represents the average for the 10-day period; 
the balance of water that of the 2-day calorimeter test. In deter¬ 
mining the water balance, on the 2 respiration-calorimeter days, the 
daily portions of the feeds as previously weighed were reweighed 
shortly before being introduced into the chamber, any difference 
being considered as representing a gain or loss of water. Also special 
samples were taken from the excreta voided in the calorimeter for 
the determination of dry matter. The nitrogen outgo was determ¬ 
ined by analysis of the fresh, undried excreta, and the carbon has 
been corrected for the loss on drying. The organic hydrogen oxidized 
in the body has been ignored as being of a magnitude of no material 
importance in the water balance. The factors and the general 
method involved are those customarily used, and, as in previous 
experiments, the schematic body is ^ assumed to consist of two 
variables, protein and fat, and a constant, glycogen. 
Table XII .—The gain or loss of water, protein, and fat per day and per head 
^Experiment, animal, and period Nos. 
Water 
Protein 
Fat 
221D-885-I_______ 
Grams 
-4,063.0 
—3,458.4 
Grams 
-45.0 
+28.2 
+16.2 
+36.0 
+25.2 
+33.6 
+103.8 
+19.8 
+25.8 
-29.4 
+16.8 
+6.0 
Grams 
+103.9 
+447.3 
+28.9 
+72.9 
+446.9 
+74.1 
+214.1 
-28.2 
+302.3 
+42.9 
+358.4 
+13.2 
II ..... ... 
III _______ 
-1,531. 5 
-9,284.7 
-6,586.4 
-5,597.2 
—3,616.3 
221D-886-I.—...... 
II........ 
III....... 
221E-885-I.....-. 
II ........ 
-1,882.5 
-6,219.7 
-2,393.2 
—3,721.5 
221F-887-I....... 
II______ t . 
221F-874-I....... 
II........ 
-1,502.7 
The animals, without exception, drank materially less water per 
day while in the respiration calorimeter than during the “ digestion” 
period. This indicates that they were varying from normal to some* 
extent while in the calorimeter. However, the actual influence of 
this variation may readily be taken into account*in the computation 
of the heat production, of the metabolizable energy, and of net-energy 
values. 
The data indicate a loss of protein, coincident with a gain of fat, in 
experiments 221D-885-I and 221F-887-II. In experiment 221E- 
885-11 the apparent balances were reversed; protein was gained 
while fat was lost. The net balances of dry matter in the mainte¬ 
nance periods show that in all cases more feed was given than was 
required to maintain equilibrium. 
In experimental series 22ID the third period for each cow was 
designed to duplicate the first. In the case of cow 885 it is apparent 
that the utilization of the feed, as measured by the gain or loss of 
protein and fat, was not the same. This difference may be ascribed 
in part to the refusal of feed in Period I, which view is substantiated 
by a comparison with data obtained in the corresponding periods 
with cow 886 in which the experimental conditions were identical 
except that there was no refused feed, the data from the two periods 
