32 
BULLETIX 1281, U. S. DEPARTMENT OF AGRICULTURE 
As in the steer experiments so also with the cows a large percentage 
difference in heat emission per minute of standing and lying was 
observed. But since Armsby himself felt that the earlier correction, 
relating the total difference in heat emission to potential energy of 
body substance, was unsatisfactory, and since at present the causes 
for the difference in heat emission between the standing and lying 
postures are not fully understood, it has been thought advisable not 
to apply a correction for standing and lying in this experiment at this 
time. Subsequent experiments, not yet studied, may add sufficient 
light to clear up this problem. 
The heat emission per minute of standing and lying has been 
computed from the heat as measured by the calorimeter, assuming 
the latent heat of water vapor to be in the same ratio as the heat 
of radiation and conduction for standing and lying. The heat pro- 
duction, as computed from heat emission by making a correction for 
the potential energy of gain or loss of body substance, is recorded 
in Table 25. 
Table 25. — Heat 'production standing and lying 
Heat production 
per minute 
Standing Lying 
Calorics Calories 
10.146 
6.942 
10. 935 
7. 16S 
11.441 
7.920 
9.224 
7.035 
9.523 
6.551 
9.465 
6.522 
10.255 
6.S16 
10. 412 
7.0S5 
1 The upper figure in this column should be read as minutes lying; the lower figure as minutes standing. 
SUMMARY 
The net energy of the feed for body increase and for milk production 
as determined for one cow was: For body increase, 1.212 Therms of 
net energy per kilogram of dry matter of feed; for milk production,. 
1.560 Therms not energy per kilogram of. dry matter of feed — a 
difference of 22.32 per cent. 
The percentage utilization of the metabolizable energy available 
for milk production ranged from 60.13 to 75.76 per cent according to 
the usual method, and 73.08 to 91.51 per cent according to the 
improved method of computing the metabolizable energy. 
The difference in the net energy values of feeds for body increase 
and milk production indicates that milk production takes place, 
normally and principally, not by the transformation of body tissue 
but by a more direct and a less expensive process. 
The computed heat production of milking cows is, on the average, 
between 2 and 3 per cent higher than the observed heat productioa 
