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A MANUAL OF VETERINARY PHYSIOLOGY 



of the more concentrated foods used by man until all feeding 

 substances used for animal nutrition have been submitted to 

 direct experiment in the animal body within the respiration 

 calorimeter. 



The application of this apparatus to problems in animal feeding 

 is well illustrated by determining the income and output of 

 energy of the steer previously referred to, where the diet was in- 

 sufficient. In the observation recorded on the balance of matter 

 at p. 349 the- steer had lost 49-2 grammes of protein, and 259 

 grammes of fat. The respiration calorimeter shows how this 

 loss affects the balance of energy. In the following table the 

 income and outgo of the energy is shown : 



Loss of energy by steer 



Income. 



Hay - 



Linseed-meal 



Faeces - 



Urine - 



Methane - 



Hair, etc. - 



Heat produced by steer 



17.572 



Outgo. 



17,572 



An analysis of the table shows that the total calories in the 

 diet was 14,859, and of these 8,357 appeared unused in the 

 various excreta. The balance of 6,502 was all that was left to 

 support the vital activities, shown in the table as equal to 

 9,215 calories. To meet the food deficit, the body tissues had 

 to be drawn upon to furnish 2,713 calories, and these were ob- 

 tained by the oxidation of 49*2 grammes of protein and 259 

 grammes of fat, the loss shown in the balance of matter at p. 349. 



The Amount of Food Required. — The minimum amount of 

 food required by horses during idleness has been determined 

 experimentally. The amount required for work cannot be fixed 

 with precision, owing to individual variations. What is suffi- 

 cient for one is insufficient for another. Still, diet tables for 

 working horses have been constructed on the basis of the mean 

 amount found by practical experience to be necessary. 



Subsistence Diet. — This is the diet necessary for the internal 

 work of the body, the weight of the animal remaining unchanged. 



