280 PRODUCTIVE FEEDING OF FARM ANiMALS 
‘studies have been of fundamental importance and through them we 
“are able to determine approximately the net energy that must be 
supplied in the feed for the production of different kinds of work 
at varying speed, on the level, or ascending certain grades, etc. 
Zuntz found that nearly one-third (31.3 per cent) of the total energy 
of feed can be converted by the horse into useful work. This is at 
least three times greater economy than that obtained in a modern 
steam engine. The energy required to masticate and digest feed 
by horses was also determined by Zuntz in an elaborate series of 
experiments; this energy was found to vary greatly with feeding 
stuffs of different character. In the case of hay, oats, and corn, for 
instance, the matter stands as follows: 
Hay Oats Corn 
Pound total digestible matter in one pound .......... 391 615 «785 
Labor expended in chewing and digestion (in terms of 
MUETIENTB!)!* wv rersess vanced awa gg avsieele ce niameres sind eae .209 219 .082 
In per ‘cent 220% comin vceng aes wns ONee oe trace tad ss 53 35 10 
In the case of coarse feeds a considerable proportion of. the 
potential energy is consumed in the processes of mastication and 
digestion, and hence lost for productive purposes, while with cereals, 
grain feeds, and roots these processes require a smaller proportion 
of the energy, and more remains for production. With some kinds 
of straw a negative nutritive value was obtained, showing that while 
a certain amount of heat was liberated in the digestion of the straw 
which was ordinarily of benefit to the animal, there would be no 
excess of energy available for production; in fact, a larger portion 
of nutrients than found in the straw would be required to supply the 
energy called for by the increased internal muscular work. 
Energy Requirements of the Horse.—Through the result of 
investigations along this line that have been conducted especially 
by German scientists we are able to calculate the energy require- 
ments of horses for a certain piece of work. Armsby gives the 
following example :? 
We will suppose that a horse weighing 1100 pounds is required to haul 
a load of one ton 20 miles a day on the level road. at a rate of 2.88 miles 
per hour, the draft averaging 100 pounds. The useful work will be in this 
ase 
5280 (feet per mile) X 20 X 100 equals 10,566,000 foot-pounds, or 3,421 
Calories. 
Since 31.3 per cent of the energy Jiberated in the body is utilized in draft, 
it will require, to perform 3421 Calories of work, 3421 divided by .313, which 
equals 10,929,000 Calories of energy in the body. It has-been found that it 
calls for an expenditure of energy equivalent to 264 Calories for a 1100-pound 
? Cyclopedia American Agriculture, vol. iii, p. 88. 
