THE MAINTENANCE EATION. 



35 



the body. Had the basal ration been entirely withdrawn, then the 

 loss would have been increased by this amount ; that is, the total loss 

 would have been 3.213+2.377=5.590 therms. The same quantity 

 would, of course, be obtained by starting- from the heavier ration 

 or from the maintenance ration as computed above. The fasting 

 katabolism, which can not well be determined directly, is thus ob- 

 tained by computation. In other words, this steer expended daily 

 5.590 therms of energy in the maintenance of his necessary vital proc- 

 esses aside from those connected with the digestion and assimilation 

 of his feed. This was his maintenance requirement as denned in the 

 foregoing paragraphs, and an amount of the clover hay which was 

 capable of supplying this quantity of available energy, viz, 5.670 

 kilograms, was a maintenance ration, while on smaller amounts he 

 drew upon his body tissues to cover the deficiency. 



£ 

















4 







Fig. 1. — Availability of metabolizable energy of hay. 



All these facts maj^ also be conveniently represented graphically 

 as follows : 



If on the two coordinate axes of figure 1, we let the horizontal distances 

 represent the metabolizable energy of the feed and the vertical distances the 

 gain of energy by the body of the animal, the results of the two experiments just 

 referred to may be represented by the points A and B, the distances OE (equal 

 to 5.687 therms) and OF (equal to 9.262 therms) representing the amounts of 

 metabolizable energy in the two rations and the distances EA (equal to 

 —2.377 therms) and EB (equal to —0.357 therm) the corresponding (negative) 

 gains of energy by the animal. A straight line drawn through A and B and in- 

 tersecting the two axes at D and C will then represent the relation between the 

 supply of metabolizable energy in the feed and the grain by the body of the 

 animal. 1 This relation may also be expressed analytically by the equation 

 y=ax — m, in which m=OD (equal to 5.590 therms) will represent the com- 



1 Assuming that this is a linear function. 



