400 VETERINARY PHYSIOLOGY 



Mode of Life. An animal kept warm and at rest requires 

 much less energy than one doing muscular work and exposed 

 to cold. 



The variations in the amount of material used in different 

 conditions is well illustrated by the experiments of Zuntz on 

 the excretion of carbon dioxide in the dog. 



C0 2 excreted per 

 minute in c.cms. 



Resting lying . . 124-7 



standing 170 '2 



Forward movement (unloaded) . . 525 '0 



(drawing weight) . 798 '9 



Muscular Work. The influence of the activity of the muscle 

 upon the metabolism has been considered on p. 67 el seq. 



In the horse the question has been very carefully studied 

 by Zuntz and Lehmann, especially as regards the intake of 

 oxygen and output of carbon dioxide. The gaseous exchange 

 was estimated either by putting a mask over the nose and 

 mouth or by performing tracheotomy, while various forms of 

 exercise without change of position were rendered possible by 

 placing the horse on a platform which could be moved at any 

 speed required, and which could be placed in the horizontal 

 or in a sloping position. 



3. Protein Requirements. The minimum amount of proteins 

 necessary to maintain health varies in different animals, but 

 a review of the ordinary dietaries of different herbivorous 

 animals indicates that it should rather exceed one grm. per 

 diem per kilo of animal weight, and that, if muscular work 

 is to be done, its amount must be increased. 



1. The Horse. The great object of feeding the horse is to 

 get work out of him, and the more work that is required the 

 more food must be given to supply the energy, or the animal 

 will draw upon the tissues of its body, and will emaciate and 

 lose the power of doing work. Since horses vary so much in 

 size and weight, it is necessary to state the dietary require- 

 ments in terms of units of weight, and the unit here taken 

 is the kilo. 



It has been found that, to maintain the weight of a horse 

 standing in its stall and doing no work, something like the 



