MAINTENANCE RATIONS 313 



and the non-nitrogenous tissues. Determinations with 

 many species of animals, including man, swine, dog, 

 rabbit, guinea pig, goose, and hen, show that the protein 

 katabolism in per cent of total katabolism varied from 7.3 

 to 15.6. In all but two cases the range was from 10.8 to 

 15.6 per cent. This shows that the energy derived from 

 the fat and carbohydrates, largely from the fat where 

 this has been stored, is from six to nine times as great as 

 from the body protein. 



413. Computation of maintenance needs. — ^The fore- 

 going data allow a computation of the metabolizable 

 energy that must be supplied in the ration in order to 

 meet the maintenance needs of the experimental animal 

 that was imder observation. 



The larger ration supplied the need of the animal to 

 within .357 therm, which was derived from body sub- 

 stance. This deficit would be equal to .632 therm of 

 matabolizable energy supplied by the hay. The computa- 

 tion would be as follows: 



Therms 



56.5 : 100 :: 357 :a:=-=energy 632 



5.3 kilos hay =energy 9.262 



Energy needed . . 9.894 



9.262 therms : 9.984 therms :: 6.3 kilos hay : x=5.655 kilos. 

 5.655 kilos =12.44 lbs. hay, or 6.34 lbs. digestible nutrients. 



The animal weighed 822 pounds. K the animal had 

 weighed 1,000 pounds, using the formula for body sur- 

 face, the figures for digestible nutrients would be 7.21 

 pounds. These figures correspond closely to those derived 

 from previous investigations. 



Aimsby suggests the following maintenance require- 

 ments based on production values for cattle, which 

 include growing animals : 



