1088 
Journal of Agricultural Research 
Vol. XXXI, No 11 
from the heat production of the corresponding period. The average 
of the several determinations is considered to represent the mainte¬ 
nance requirement of the animal during the series of experimental 
periods. 
(5) The toal net energy of each ration is computed by adding to 
the gain, as obtained in (1), the average net energy required for 
maintenance, as obtained in (4). 
(6) The net-energy value per kilogram of dry matter of feed is 
computed by dividing the total net energy of the feed by the dry 
matter (kilogram) of the feed. 
(7) The percentage utilization of the metabolizable energy is com¬ 
puted by dividing the total net energy of the feed by its total metab¬ 
olizable energy, and multiplying the result by 100. 
INCREMENTS OF HEAT PRODUCTION PER KILOGRAM OF DRY 
MATTER OF FEED 
The feeds used in the experiments under consideration consisted 
in some cases of coarse fodder alone, and in others of a mixture of 
roughage and concentrates (Table II). The increments of heat pro¬ 
duction per kilogram of roughage alone, or of a uniform mixture of 
hay and grain, are computed directly, as outlined above, by com¬ 
paring the periods in which different quantities of the same feed, or 
of the same mixture of feeds, were consumed. 
In the experiments following No. 207 the rations consisted of a 
uniform mixture of feeds, in the different periods. The increments 
of heat production, therefore, are computed per kilogram of the mix¬ 
ture, these values being directly usable for the computation of the 
maintenance requirement of the animal. 
In the earlier experiments, however, up to and including No. 207, 
the hay and grain were not fed in the same proportion in the different 
periods. In these the heat increments per kilogram of the grain have 
been computed by making use of the hay periods in the comparisons. 
The heat increment values of the feeds, as obtained by the use of 
the heat production corrected to 12 hours standing and 12 hours 
lying, according to the new method, and the averages of each series, 
are set forth in Table III. 
