22 
BULLETIN 1281, U. S. DEPARTMENT OF AGRICULTURE 
actual water balance from the calorimeter period. The dry matter 
representing irregularity in the excreta and production of milk is 
the difference between the daily average for the experimental period 
and the amount produced during the calorimeter period. 
The daily balances for the different periods and animals show a 
great variation, ranging from + 7.2 kilograms to —19.1 kilograms 
change in live weight. This clearly demonstrates the unreliability 
of live weight as a measure in exact experiments, and the necessity, 
in work in which live weights must be used, of basing conclusions on 
an average of several successive daily weights. A single weighing 
may happen to be correct, but, on the other hand, according to the 
above figures, it may be decidedly wrong, especially when intended 
to measure the gain or loss of body tissue. 
HEAT PRODUCTION 
To correct the heat emission for the change in live weight, in 
computing the heat production at a constant weight, the following 
factors for specific heat have been used: Water equals 1, dry matter 
equals 0.4, body protein and fat equals 0.3 and 0.66, respectively, 
the last two being estimated values as used by Armsby and Fries. 
The heat correction for the body gain or loss in live weight as thus 
computed is found in Table 18, which also gives the daily heat 
production. 
The corrections for change in live weight are considerable, ranging 
as they do from +132.1 to -419.7 Calories. 
COMPUTED HEAT PRODUCTION 
For various reasons it is desirable to compute the heat production 
of an animal (indirect calorimetry) from the results of the gas and 
dry-matter analyses. Making this computation for a milking cow, 
under varying conditions, is a new problem and one which requires 
discussion. 
Table 18. — Correction for change in live weight, and daily heat -production 
Period 
Body loss (-) or gain (+) 
Irregular 
excretion 
of dry 
matter 
Tempera- 
ture dif- 
ference 
Correc- 
tion 
Daily heat 
Cow No. 
Water 
Protein 
Fat 
Emission 
(corrected) 
Produc- 
tion (cor- 
rected) 
631 
615 
579 
1 II 
I III 
f I 
1 H 
I HI 
I .: 
Orams 
-18,894.2 
+5, 585. 7 
-10,536.2 
-13,851.8 
-3, 250. 5 
-17,546.5 
-20, 772. 9 
-17,086.4 
Grains 
-24.0 
-36.0 
+115.8 
+20.4 
-7.2 
-42.6 
+57.0 
+10.8 
Grams 
+37.7 
+407. 2 
+337. 2 
+40.6 
-12.6 
-42.9 
+6.3 
+65. 8 
Orams 
f - i 66. 
\+ 2 578. 6 
/ -52. 3 
1+1,332.5 
+614. 1 
/ -3.5 
\ +874. 3 
/ -44. 5 
\ +941.0 
/ -31.7 
\ +617.8 
/ +8.0 
\ +740. 
/ +26. 5 
I +641.6 
°C. 
} 20. 53 
| 20. 79 
21.02 
| 20. 68 
\ 20. 59 
\ 20. 68 
[ 20. 52 
[ 20. 99 
Calories 
-383.3 
+132. 1 
-210.9 
-278. 6 
-59.8 
-358. 8 
-419.7 
-352. 
Calories 
11,847.2 
12, 201. 8 
13, 430. 1 
11,714.1 
12, 197. 1 
12,391.0 
13, 655. 3 
13, 248. 2 
Calories 
11,463.9 
12,333.9 
13,219.2 
11,435.5 
12,137.3 
12, 032. 2 
13, 235. 6 
12, 896. 2 
Milk. 
2 Excreta. 
A milking cow may be maintaining her body tissue; 
or gain both body protein and fat, or she may lose one 
other. These different conditions of body loss or 
appropriately differing consideration. 
she may lose 
and gain the 
gain require 
