48 PRINCIPLES OF FEEDING FARM ANIMALS 
By means of the respiration calorimeter the amount of heat 
produced by the oxidation of the digested nutrients in the animal 
body is determined. The distribution of the losses of energy to 
the animal in the dung, urine, and marsh gas, as well as the net 
energy contained in the different feeding stuffs, is also shown by 
the results obtained in trials with this apparatus. 
The following table shows the distribution in therm units in 
the case of three common feeds, as determined by Armsby: 
Energy in Different Feeding Stuffs per 100 Pounds, in Therms 
Clover hay Corn meal - Wheat straw 
Total energy........... 172.1 170.9 171.4 
Losses in dung. .73.6 15.7 93.9 
Losses in urine. .11.5 6.5 4.3 
Losses in marsh 
CaS osyanas. 2.3 15.9 15.5 
Total losses........ 97.4 38.1 113.7 
Available energy, balance 74.7 132.8 57.7 
Available in per cent.... 43 78 34 
We note that, while clover hay and corn meal contain nearly 
the same amount of total energy, only 43 per cent of this is avail- 
able to animals in the case of clover hay, against 78 per cent in the 
case of corn meal. 
Available Energy.—These figures and others similarly obtained 
do not, however, tell the whole story. Clover hay and other rough 
feeds, are bulky and call for a large amount of work in mastication 
and moving it through the alimentary canal, and also necessitate 
the secretion of larger amounts of digestive fluids than do corn 
_meal ‘and other concentrates. The energy required for these pur- 
poses is likewise lost to the animal, so far as production or work is 
concerned, and can be provided only through that supplied in the 
feed. The balance, which is known as net available energy or net 
energy, represents that available to animals for maintaining the 
vital functions or for productive purposes. 
The results obtained in respiration experiments-with steers show 
that a larger percentage of the energy value of concentrated feeds 
is available for maintenance or for production than in the case of the 
rough feeds. In the poorest of these, as wheat straw, only small 
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