
86 STORRS AGRICULTURAL EXPERIMENT STATION. 
with the amount supplied, as in the case of the fuel placed in the stove; but 
this comparison is not apt. The amount of oxidation in the organism is influ- 
enced solely by the amount required for performing labor or producing heat, 
and not at all by the amount of nutrients which may be present. ‘This has been 
shown by von Mering and Zuntz.* They introduced solutions of nutrients in 
considerable quantity directly into the blood of animals and found that the con- 
sumption of oxygen was not at allincreased. The extra nutrients were stored up 
by the animal as reserve material. Therefore the increased oxygen consumption 
immediately after eating can only be produced by the labor of digestion. 
‘‘In feeding with a normal mixture of oats and hay the increased oxygen con- 
sumption is 10.7 per cent., and when hay only is fed, the amount being just 
sufficient to maintain the animal and permit a very little work to be done, it is 
1g.8 per cent. in excess of the amount of oxygen consumed when fasting. In 
this case also it may be seen that the bulky hay requires more energy for its 
digestion than the more concentrated food.” 
‘‘It is evident that the unequal ‘ease of digestion’ materially changes the 
nutritive value of feeding stuffs from the values which are derived simply from 
their chemical composition. The nutrients which are assimilated from coarse 
fodder yield the organism about 20 per cent. less available energy than the same 
amount assimilated from grain, since the coarse fodder requires so much more 
energy for its digestion. 
‘‘ Respiration experiments furnish accurate information concerning the quan- 
tity of nutrients which is required for the performance of various kinds of work. 
They show more clearly than any previous method how much of the energy of 
the assimilated nutrients is available for the organism after the labor of diges- 
tion is accomplished. ‘They give no information, however, as to what combina- 
tion of nutrients is best suited for the production of the greatest possible amount 
of muscular energy. 
‘* The general practice of feeding work animals a ration rich in protein is in 
harmony with Pfliiger’s observations. The dog which he fed for months on 
meat only was able to perform severe muscular labor. Often, however, even 
dogs could not digest a sufficient amount of protein. Ona diet of protein the 
digestive juices which are adapted for the assimilation of fat and carbohydrates 
are not utilized. When it is desired to feed an anima a ration which will give 
the maximum amount of work, a combination of nutrients must be selected 
which will utilize all the energy available for digestion. Care must be taken 
also not to feed too much coarse fodder, since it has been seen that such food 
materially increases the labor of digestion. On the other hand, coarse fodder 
- must not be omitted altogether. Grandeau and Leclerc} have shown that dis- 
turbances of the digestive organs are produced when horses are fed entirely on 
grain. At all events, grain should form the greater part of the ration of horses 
which perform severe work.”’ 
FOOD REQUIREMENTS OF THE ANIMAI, ORGANISM. 
The animal uses its food for various purposes, the chief of 
which are: (1) To build up the tissues and fluids of the 
body, which may be regarded as a machine, and to keep it in 
* Pfliiger’s Arch, Physiol., 32, p. 173. 
+ Etudes expérimentales sur l’alimentation du cheval de trait, 1883, 1887, and 1889. 


