responding to Rubner's "specific dynamic effect", the heat pro- 

 duction rising from 5635.8 Cals. to 6559.9 Cals. It is customary 

 in such a case to speak of the 1415.9 Cals. as the available energy 

 of the hay added to the basal ration of Period III and to say that 

 60.5 per cent, of the metabolizable energy of the hay was available. 

 Such a method of statement does not necessarily imply that the 

 remaining 39.5 per cent, served no useful function in the body, but 

 simply asserts that the net result to the organism was the same as 

 if 60.5 per cent, of the metabolizable energy were substituted unit 

 for unit for energy derived from the katabolism of body substance 

 and as if the remaining 39.5 per cent, were useless. What the ex- 

 periment really shows is that a unit of metabolizable energy in the 

 hay had only 60.5 per cent, of the value of a unit of metabolizable 

 energy in the body substance, (chiefly fat) previously katabolized. 

 but the first method of expression is both common and convenient 

 and may be retained. 



Experimental Results. 



After correcting for differences in the amount of time spent 

 standing and lying, for the slight variations in the live weight in 

 the periods compared and for slight unavoidable differences in the 

 proportion of hay or grain in the mixed rations, the average re- 

 sults are as shown in Table 4. Those for hay in the year 1906, as 

 indicated, are of questionable value. 



Table 4. Summary of Availability of Metabolizable Energy. 



Taking the results as a whole, they seem to indicate a small 

 but distinct superiority of the pure-bred over the scrub steer as 

 regards the availability of the metabolizable energy of the feed. 



(10) 



