226 



NUTRITION OF FARM ANIMALS 



Figure 33 shows a form of this apparatus used by Zuntz for 



work experiments upon horses. 



Another method for measuring kinetic energy consists in 



converting it into electrical energy by causing the subject to 



work against the resistance 

 of a magnetic field. The 

 amount of current thus gen- 

 erated can be measured in 

 electrical units, or, as has 

 been done by Atwater, Bene- 



Idict and others, the electrical 

 energy may be converted into 

 heat and measured in calories. 



The body's income of energy. 

 Gross energy 



314. Only chemical energy 

 can be utilized. As was 

 stated in the introductory 

 paragraphs of this chapter, 

 the animal body resembles an 

 internal combustion motor in 

 being a mechanism for the 

 conversion of the chemical 

 energy of certain compounds 

 contained in the feed into 

 kinetic energy. In consider- 

 ing the balance between in- 

 come and outgo of energy, it 

 is essential to recognize a 

 further point of resemblance, 

 viz., that neither the animal 

 nor the motor can utilize 

 other than chemical energy. 

 There is no evidence that the 

 animal body can use in any 

 way any of the other forms 

 of energy, such as heat, elec- 

 tricity or solar radiation 



