1062 
Journal of Agricultural Research 
Vol. XXXI, No. 11 
In Table VII the coefficients of apparent digestibility, computed 
as explained above, have been collected. The averages are arith¬ 
metic, not weighted, means. 
Table VII. — Coefficients of apparent digestibility (feed minus feces) 
Experiment, 
animal, and period 
Nos. 
Dry 
matter 
Organic 
matter 
Pro¬ 
tein 
Non- 
pro¬ 
tein • 
Crude 
fiber 
Nirto- 
gen 
free- 
extract 
Ether 
extract 
Total 
nitro¬ 
gen 
Carbon 
Organic 
matter 
as 
energy 
Per 
Per 
Per 
Per 
Per 
Per 
Per 
Per 
Per 
Per 
cent 
cent 
cent 
cent 
cent 
cent 
cent 
cent 
cent 
cent 
221D-885-I_ 
70 
72 
75 
73 
48 
80 
80 
75 
70 
71 
. 
70 
72 
72 
72 
49 
81 
82 
73 
69 
6 ft 
Ill.- 
74 
75 
77 
77 
50 
84 
82 
78 
73 
7a 
Average_ 
71 
73 
75 
74 
49 
82 
81 
75 
71 
71 
221D-886-I_ 
72 
74 
78 
75 
48 
82 
80 
78 
71 
71 
II_ 
70 
72 
75 
67 
48 
80 
79 
74 
70 
70. 
III.- 
72 
73 
74 
75 
47 
82 
80 
75 
71 
71 
Average... 
71 
73 
76 
72 
48 
81 
80 
76 
71 
71 
221E-885-I__ 
73 
74 
80 
68 
49 
82 
83 
79 
72 
72 
II_ 
73 
74 
76 
82 
45 
82 
84 
78 
72 
72 
Average_ 
73 
74 
78 
75 
47 
82 
84 
79 
72 
72 
221F-874r-I. 
68 
70 
71 
73 
46 
78 
79 
73 
67 
67 
II_ 
70 
72 
74 
74 
47 
79 
80 
75 
69 
69 
Average.. 
69 
71 
73 
74 
47 
79 
80 
74 
68 
68 
221F-887-I.—- 
68 
69 
73 
46 
46 
77 
79 
69 
65 
67 
II_ 
74 
75 
78 
67 
48 
84 
84 
77 
73 
74 
Average. .. 
71 
72 
76 
57 
47 
81 
82 
73 
69 
71 
° Nonprotein, NX4.7. 
THE LOSS OF NITROGEN AND CARBON ON DRYING SAMPLES 
OF EXCRETA PRIOR TO GRINDING 
The loss of nitrogen and carbon in drying during the preparation 
of the samples for analysis has been a recognized source of error 
throughout the entire series of investigations with the respiration 
calorimeter. In the experiments with steers the feces and the urine 
were handled separately, and the loss on drying the feces was found 
to be small, and was disregarded; while the energy was corrected for 
the urinary loss on the basis of Rubner's figure of 5.45 Cal. per 
gram of nitrogen lost on drying. The data for the first experiment 
with cows, 221 A, were also handled in this way, as the feces and 
urine were collected separately. 
In all experiments with these cows subsequent to 221A it was 
necessary to collect the feces and urine as a mixture, and it was soon 
recognized that the physical state of this mixture, particularly its 
moisture content, might be important in relation to fermentation 
during preparation for analysis. The decomposition of these mixed 
samples during drying was greater than that of either the dung or 
the urine alone, and especially significant was it that more carbon 
was lost than could be accounted for as originating in the nitrog¬ 
enous compounds of the urine in the mixture. There is a possi¬ 
bility, however, that the loss of nitrogen observed may be somewhat 
less than the true loss, since fixation of nitrogen has been shown ta 
occur in drying feces (8 ). 
