FUNCTIONS OF THE NUTRIENTS 181 



feeds. It seems, from the later determinations, however, 

 that when all factors are considered, the difference in the 

 total energy expenditure in the two classes of feeds is not 

 greatly unlike. 



263. Estimation of production values proposed by 

 Armsby. — Instead of using net or production values as 

 experimentally determined for each individual feed, 

 Armsby has computed a table based largely on the 

 results of investigations by Kellner. 



This investigator arrived at what is termed the pro- 

 duction values of ptu*e nutrients, such as a single pro- 

 tein, starch, or one of the fats. His figures are as follows: 



Table XLII. Production Values per Pound 



Calories 



Digestible proteins 1016 



Digestible starch or crude fiber 1071 



Digestible cane-sugar 812 



Digestible fat — 



In coarse fodders and roots 2041 



In grains and by-products 2273 



In feeds with over 5 per cent fat 2685 



In making up the tables of production values, these 

 values for pure nutrients are used in connection with a 

 given allowance for the expenditure of energy in mastica- 

 tion due to the presence of crude fiber. Kellner found it 

 was possible to estimate fairly accurately the production 

 value of concentrated feeds by means of these factors, but 

 in the case of the coarse fodders carrying a much higher 

 prc^ortion of fiber such a method of computation was 

 not reliable. He found, however, that if he deducted 

 from the figures obtained through the use of the produc- 

 tion values for piu-e nutrients 617 calories for each pound 

 of crude fiber in the coarse fodder the computed value 



