288 NUTRITION OF FARM ANIMALS 



TABLE 45. DAILY MAINTENANCE RATIONS OF SWINE 

 Metabolizable energy per 100 Ib. live weight 



Maximum 2.558 Therms 



Minimum 0.897 Therm 



Average of all 1-534 Therms 



Average omitting lowest and highest . . . 1.510 Therms 



Average omitting lowest and two highest . . 1.474 Therms 



379. Comparison with net energy. On the average of all 

 the respiration experiments on fattening swine which are re- 

 corded in Chapter XVII (761), 78.14 per cent of the metab- 

 olizable energy supplied may be computed to have been uti- 

 lized for maintenance plus gain. If this may be assumed to 

 represent approximately the percentage of the metabolizable 

 energy available for maintenance, the foregoing maintenance 

 rations contained, per 100 pounds live weight, the following 

 amounts of net energy: 



TABLE 46. DAILY MAINTENANCE RATIONS OF SWINE 

 Computed net energy per 100 Ib. live weight 



Minimum 0.701 Therm 



Maximum 1.998 Therms 



Average of all i-JQQ Therms 



The averarge requirement of net energy as thus computed 

 does not differ greatly from the amount indicated by the ex- 

 periments on fasting animals (377), but the enormous range in 

 the results of the single experiments shows in a striking manner 

 the need for further investigation. 



The maintenance requirement of cattle 



380. Net energy requirement. In the case of ruminants, 

 it is hardly practicable to determine directly the net energy re- 

 quirement by measuring the katabolism of the fasting animal. 

 Prolonged fasting would be required to free the voluminous 

 and complicated digestive organs of these animals from feed 

 residues, if this could be accomplished at all, and it would be 

 difficult to determine when that point was reached, while it is 

 questionable whether the results on such an animal could be 

 regarded as normal. 



