Sept. 1,1925 
Net-Energy Values of Feeding Stuffs 
475 
The new method calls for a determination of the maintenance 
requirement (m) of net energy. This is obtained by subtracting the 
computed heat increment, due to the consumption of the feed, from 
the heat production of each period, in accordance with the principles 
outlined by Armsby (8, p. 282). The average of the several deter¬ 
minations is considered to represent the maintenance requirement of 
net energy. To this net energy for maintenance is added the gain 
of energy by the animal in eacn period, as obtained by subtracting 
the total heat production from the total metabolizable energy (Table 
II), and the result represents the total net energy of the ration, from 
which the net-energy value of the feed is computed. The specific 
directions for the computations, and the results obtained with the 
timothy hay and grain mixture No. 1, previously considered, are as 
follows: 
COMPUTATION OF THE HEAT-INCREMENT VALUE OF THE FEED 
The computation of the heat increment per kilogram of feed is 
exactly as in the current method. To avoid repetition, reference is 
made to the foregoing description of the current method, and to 
Tables III and IV, which illustrate this computation and give the 
heat-increment values. If there is more than one value for a feed, 
the average is used. This is a departure from the current method, 
in which, the value obtained by comparison of only the two extreme 
rations was used. The reasons for this departure will be given later. 
There is only one heat-increment value for the hay—namely, 897 
Calories per kilogram of dry matter; and there are three values for 
the grain mixture—namely, 1,215 Calories, 1,394 Calories, and 1,319 
Calories per kilogram of dry matter. The average of these is 1,309 
Calories. 
COMPUTATION OF THE NET ENERGY REQUIRED FOR MAINTENANCE 
Multiply the average heat-increment value per kilogram of the 
feed by the kilograms of dry matter of each ration. The result is 
the total heat increment due to the feed. In case of a mixed ration 
of hay and grain, not fed in the same proportion in the different 
periods, multiply the kilograms of hay and of grain separately by 
their respective average heat-increment values, and add the results, 
to get the total heat increment due to the ration. Subtract the total 
heat increment from the heat production. The remainder is the net 
energy required for maintenance. Average the values thus obtained 
for the maintenance requirement of net energy. 
Table V. —Computation of maintenance requirement 
Period No. 
Dry matter eaten 
Average heat incre¬ 
ment per kilogram 
of dry matter 
Total 
heat 
increment 
of 
ration 
Total 
heat 
produc¬ 
tion 
! Net 
| energy 
for 
1 mainte¬ 
nance 
! _ . 
Timothy 
hay 
Grain 
mixture 
Hay 
Grain 
1..... . 
Kgms. 
2.9349 
2.9487 
2.9742 
4.8920 
Kgms. 
1.9962 
4.7590 
Cals. 
897 
897 
897 
897 
Cals. 
“1,309 
« 1,309 
Cals. 
5,246 
8,875 
2,668 
4,338 
Cals. 
10,171 
14,035 
' 7,780 
Q KOI 
Cals. 
4,925 
5,160 
) 5,113 
2.... 
3..... 
4... 
Average.. 
5,066 
“ Average of all values. 
