Dec. 1,1925 
The Maintenance Requirement of Dry Cows 
1061 
The results obtained by the analysis of the dung and urine mixture 
as shown in Table V are used to obtain the balance of matter, and 
are the basis of all computations except those relating to the apparent 
digestibility. Here again the loss of nitrogen and carbon during 
drying is evident, this loss apparently being due to fermentation. 
THE APPARENT DIGESTIBILITY OF THE RATION 
In order that the method by which the writers have arrived at an 
approximation of the apparent digestibility of the various constituents 
of the ration may be clear, the- computation for experiment 22 ID- 
885-1 has been included in detail m Table VI. The method is 
based primarily on the assumption that the percentage composition 
of the dry matter of the dung is approximately constant for a given 
ration, an hypothesis which seems to be justified by an examination 
of data previously published from the institute. In connection with 
the second part ox the computation (the fresh weight of the dung 
alone) it has been necessary to assume the percentage dry matter of 
the dung alone to be a constant on a given ration. There is a measure 
of uncertainty in this assumption. However, since this factor 
affects only the urine, no great error results from this procedure. 
Table VI. — Example of computation of apparent digestibility (221D-885-I) 
FEEDS AND EXCRETA; FRESH AND DRY BASIS 
Average daily feeds and excreta; fresh weights; 10-day period | Dry matter 
Alfalfa hay - - __ _ -_ _ - -_ 
Kg. per 
day 
1.779 
Per cent 
89.26 
Grams 
per day 
1,588 
2,302 
30 
Mixed grain_____ __ _ 
2.668 
86.28 
Salt-- -. _ - -_ _ -- 
.030 
98.77 
Refused feed._ __ __ __ 
.252 
88.25 
223 
Dung and urine. _ _ _ ____ __ 
9.415 
14.29 
1,346 
3 
Apron scrapings_____ _ ___ _ _ 
.020 
14.29 
Computed dung alone____ ___ _ 
4.574 
1,095 
254 
Computed urine alone _ _ _ _ __ 
4.862 
Spilled urine_ _ __ ____ __ 
.007 
Total urine.. _ ___ ___ 
4.869 
254 
Totals: 
Dung and urine mixture _ __ __ ___ 
9.443 
Dung alone_ _ _ ___ _ __ 
4.574 
Urine alone___ _____ 
4.869 
CONSTITUENTS OF FEEDS AND EXCRETA 
Dry 
matter 
Organic 
matter 
Pro¬ 
tein ° 
Non- 
pro¬ 
tein b 
Crude 
fiber 
Nitro¬ 
gen-free 
extract 
Ether 
extract 
Total 
nitro¬ 
gen 
Carbon 
Energy 
Salt . 
Grams 
29.6 
Grams 
Grams 
Grams 
Grams 
Grams 
Grams 
Grams 
Grams 
Cals. 
Alfalfa hay... 
1,588.0 
1,463.3 
176.2 
37.5 
601.1 
616.2 
32.2 
36.2 
731.7 
7,208.6 
Mixed grain_ 
2,302.0 
2,194.0 
302.2 
49.3 
207.7 
1,522.1 
112.8 
62.1 
1,064.6 
10,648.0 
Refused feed_ 
222.6 
208.3 
32.7 
6.2 
24.1 
136.4 
8.9 
6.6 
101.5 
1 , 012 .7 
Total eaten_ 
3,697.0 
1,095.0 
3,449.0 
445.7 
80.6 
784.7 
2 , 001 .9 
136.1 
91.7 
1,694.8 
16,843.9 
c 4,949.0 
Dung.. 
964.9 
112.0 
21.4 
410.8 
393.6 
27.2 
22.5 
500.5 
Total digested..._ 
2,602.0 
2,484.1 
333.7 
59.2 
373.9 
1,608.3 
108.9 
69.2 
1,194.3 
11,894.9 
Per cent digested. 
70 
72 
75 
73 
48 
80 
80 
75 
70 
71 
a True protein; A. O. A. C. method. 
b Nonprotein, NX4.7. 
« Corrected for loss on drying (see Table VIII for method and factors used): 
Computation of dung in mixture: 
Dry matter of dung and urine mixture : X :: per cent crude fiber in dung alone: per cent crude fiber 
in dung and urine mixture. 
1,349X30.46 , _ 
• ~ 3 7 5 2 — =1,095.0 grams. 
Computation of fresh weight of dung: 
Dry matter of dung alone (computed) : X :: per cent of dry matter of dung alone : 100 
1 -^^ xl 0 °=4,5 7 4 grams. 
