VALUATION OF FEEDING STUFFS 219 



but such is clearly implied. The fat-forming power of any 

 substance that is not digested or that is spent in the work of 

 digestion is zero. The relative fat-forming power which 

 Kellner ascribes to the several nutrients is as follows : 



of starch. 



i Ib. of diges- 1 ! n oil y ******** oil cakes = 2-41 Ibs 



tible fat I in cereal and P ulse g rams = 2'I2 , 



( in coarse fodders (hay, straw, etc.) = 1*91 , 



i Ib. of digestible carbohydrates and fibre = I'oo , 



i Ib. of digestible protein - 0^94 , 



The starch value of a food is, therefore, determined by 

 multiplying the percentages of the digestible nutrients by these 

 factors respectively, and deducting from the sum of the 

 products a certain percentage which represents the amount 

 spent on the work of digestion. This amount, of course, 

 depends upon the kind of food. It is simply the percentage 

 difference between the thermic and dynamic values of the 

 food. It may be found by deducting the figures given in 

 the fifth column of the tables (p. 166) from 100. The same 

 result is obtained by multiplying the sum of the products by 

 the numbers given and dividing by 100. The final result 

 is called the "starch value" or "starch equivalent" of the 

 food. 



For example, the starch value of a sample of bran was 

 determined as follows : 



Digestible nutrients. Per cent. Factor. Starch value. 



Protein . 10 X 0^94 = 9*40 



Fat 3 x 2'i2 6 - i6 



Soluble carbohydrates and fibre .45 X I'oo = 45'OO 



60-56 

 Deduct 23 per cent, for work of digestion . . . 13-93 



Total starch equivalent of the food . . . . . 46*63 



or (vide supra) 60-56 X 077 = 46-63. 



This means that 100 Ibs. of bran is equivalent to, i.e. has 

 the same fattening power as, 46-63 Ibs. of pure starch. 



Coarse fodders are not suitable or economical for fattening, 

 and if the maintenance rations are considered separately, as 

 recommended, the marked inferiority of the fat in hay and 



