394 
Joumal oj Agricultural Research 
Vol. XXX, No. 5 
A comparison of the observed and 
computed heat production in experi¬ 
ments with steers, conducted in the 
years prior to and including 1909, has 
been reported by Armsby (6). Since 
the year 1909 a number of experiments 
have been made on steers, and on cows 
as well, and upon these the present 
paper is based. 
OBSERVED AND COMPUTED HEAT 
PRODUCTION 
Before entering upon a discussion of 
the direct and indirect methods of 
determining the heat production by 
animals let us compare the results 
obtained by the two methods. Tables 
I and II present the results of experi¬ 
ments with steers and cows, the steer 
experiments comprising 35 periods and 
the cow experiments 36. Each period 
was of 48 hours’ duration (except in 
experiment 221a and 221d, 886-1, 
where the periods were 24 hours) . 3 
All results have been computed to a 
24-hour basis. 
The results of the steer experiments 
show that in 21 cases out of the 35 the 
computed heat production is higher 
than the observed; in 10 cases the 
computed heat is lower than the 
observed, and in 4 cases the difference 
between the two is so small as to be 
negligible. 
Considering the differences in the 
individual trials, and arranging them 
in groups according to magnitude, the 
results are as follows: In 21 cases, or 
60.0 per cent of the total number, the 
difference exceeds 1 per cent, of which 
13 are plus (that is, show the computed 
heat production the larger); in 14 
cases, or 40.0 per cent of the total 
number, the difference exceeds 2 per 
cent, of which 10 are plus; in 6 cases, 
or 17.1 per cent of the total number, 
the difference exceeds 3 per cent, of 
which 5 are plus; in 2 cases, or 5.7 per 
cent of the total number, the difference 
exceeds 4 per cent, of which both are 
plus; and in 2 cases, or 5.7 per cent of 
the total number, the difference exceeds 
5 per cent, of which both are plus. 
Table I .—Observed and computed heat production of steers 
Experiment No. 
Animal 
Period 
No. 
Gain by 
animal 
Heat production in 
24 hours 
Difference 
Computed 
Observed 
Calories 
Calories 
Calories 
Calories 
Per cent 
I _ 
-845. 7 
9, 262.9 
9,460.6 
-197. 7 
-2.1 
210_ 
Steer D... 
II_ 
-1,141. 5 
8,026.1 
8,186.0 
-159.9 
-1.9 
III_ 
-2,153. 8 
6, 942. 0 
7,110.4 
-168.4 
-2.4 
I _ 
-883. 2 
12,139.1 
11, 546.9 
+592. 2 
+5.1 
II_ 
-496. 9 
9, 813. 8 
9, 596. 5 
+217. 3 
+2.3 
211 
_do_ 
III_ 
+7, 663. 8 
13, 815. 6 
13, 937. 2 
-121.6 
-0.9 
IV _ 
-2, 462.1 
9', 227.4 
9', 196. 5 
+30.9 
+0.3 
.V .. 
-4,968. 6 
8,010. 9 
7, 952. 9 
+58.0 
+0.7 
I _ 
+327. 9 
11,642.1 
11,710.8 
-68.7 
-0.6 
II_ 
-1, 565.5 
8, 229. 9 
8,197. 0 
+32.9 
+0.4 
211 _ 
Steer G _ 
III_ 
+6,133. 6 
12,807. 3 
13, 290. 2 
-482. 9 
-3.6 
IV_ 
-2. 981. 5 
8,942. 6 
8; 936. 5 
+6.1 
+0.1 
' 
V_ 
-4,154.1 
6, 894. 8 
6,882. 5 
+12.3 
+0.2 
I _ 
+2, 241. 2 
11,130. 7 
11,022.9 
+107. 8 
+1.0 
. ; 
II._ 
+2, 529. 3 
10, 690.4 
10,903.4 
-213. 0 
-1.9 
df AA> , TJ 
III _ 
+840. 4 
9, 712. 9 
9, 723.1 
-10.2 
0. 1 
212 _ 
oLGBF xx- 
IV _ 
+859. 9 
9, 805. 8 
9. 701. 6 
+104.2. 
+1.1 
V _ 
-739. 6 
7, 296. 0 
7,304. 9 
-8.9 
-0.1 
VI . 
-409. 8 
6,950. 4 
6, 773.1 
+177. 3 
+2.6 
fl_ 
+5, 111. 5 
15,931. 6 
15, 541. 2 
+390.4 
+2. 5 
II _ 
-1,046.5 
9,836.3 
9, 547. 2 
+289.1 
+3.0 
III . 
+596. 7 
11,420. 2 
10,865. 8 
+554.4 
+5.1 
216 __ 
Steer J _ : 
<IV _ 
-2,672. 9 
8,186. 4 
8,020.4 
+166. 0 
+2.1 
V. . 
+2, 299. 7 
12,820. 9 
12,827. 5 
-6.6 
0.1 
VI _ 
+907.3 
11,062.8 
10,838. 2 
+224. 6 
+2.1 
.VII . 
-1,708.8 
8, 501. 5 
8,398.4 
+103.1 
+1. 2 
fl_ 
+927. 2 
11, 240. 9 
10,896. 8 
+344.1 
+3.2 
II _ 
+8,493.1 
16,934. 8 
16,671. 7 
+263.1 
+1.6 
217 . --- 
im _ 
+6,463. 3 
21,416.0 
21,204. 9 
+211.1 
+1.0 
IV_ 
-559. 6 
14,716.0 
14,224.4 
+491. 6 
+3.5 
ri _ 
-626.0 
11,881. 5 
12,123. 6 
-242.1 
-2.0 
ii _ 
-2,270.5 
10,108.7 
10,288.1 
-179.4 
-1.7 
220 __ 
Steer K _ _ _ 
\ui _ 
+464.5 
10,809. 7 
10,754. 2 
+55.5 
+0.5 
IV_ 
+4, 644. 5 
13,524. 3 
13,844. 0 
-319. 7 
-2.3 
lv.. 
-2,951. 5 
10,136. 3 
10,055. 8 
+80.5 
+0.8 
Totals and aver- 
ages, 35 periods.. 
379,868. 6 
377,535. 2 
+2,333. 4 
+0.6 
3 Period 886-1, experiment 221d, was to have covered 48 hours, but owing to the failure of the electri 
curront the experiment was discontinued during the second 24 hours. c 
