196 AN AGRICULTURAL WAR PROBLEM 



grams of fat, 1000 grams of linseed cake having 

 this starch equivalent should cause the production 

 of 196 grams of fat. Direct experiment however 

 showed that 1000 grams of this particular linseed 

 cake produced only 192 grams of fat, or 98 per 

 cent, of the amount which it ought to have pro- 

 duced if the calculated starch equivalent were 

 really exact. The true starch equivalent was then 

 calculated from the calculated starch equivalent by 

 multiplying the latter by 98 -f- 100. This figure 98 

 which gives the ratio of the true starch equivalent 

 to the calculated starch equivalent was called by 

 Kellner the value number. It expresses the ratio 

 of the true starch equivalent to the starch equiva- 

 lent calculated from the percentage of digestible 

 nutrients by Kellner's method. Kellner deter- 

 mined the value numbers for all the different 

 classes of foods. By the aid of these and the 

 values of the separate digestible nutrients he was 

 able to assign starch equivalents to all the 300 

 foods included in the list he gives in his book. 

 For instance the starch equivalent of average 

 meadow hay was calculated thus: 



Digestible nutrients 

 per cent. 



Protein 4*6 x 0-94 = 4*32 



Fat 0-6 x 1-90 = i '14 



Carbohydrates... 2ri x ro = 21-10 



Fibre 15-3 x ro - 15-30 



41-86 



