228 Concentrated Feeding-stuffs. [June, 



foodstuffs, and may be allowed for by deducting from the 

 total of food-units (including in this case the digestible fibre) 

 one unit for every 3 per cent, (or 2 per cent, in the case of 

 hays and straws) of crude fibre (total) present in the food. 



Thus, suppose it is desired to compare the decorticated 

 cotton cake of Example II. with an undecorticated cotton 

 cake containing 22 per cent, of albuminoids, 5f per cent, of 

 oil, 34 per cent, of carbohydrates and 20 per cent, of crude 

 fibre. This composition would correspond (Table, p. 225) 

 to the following percentages of digestible nutrients: — Albu- 

 minoids 17, oil 5J, carbohydrates 17!, and fibre 3f. 



Decorticated cotton cake of average quality will contain, 

 say, 8 per cent, of crude fibre, and hence 2\ per cent, of 

 digestible fibre. 



Then the total number of food-units in each case will be — 



Decort. Cotton Cake ... (8£ x 2\) + 34^ +18 + 2j = 76. 

 Undecort. Cotton Cake... (5^ x 2\) + 17 + 17I + 3 J = 52^. 



These totals must now be subjected to the deduction, 

 referred to above, based upon the percentages of crude fibre 

 in each food. The corrected totals then become : — 



Decort. Cotton Cake ... 76 = 73. 



Undecort. Cotton Cake... 52^ - \° = 45 J. 



The nett cost per unit of the decorticated cotton cake is 



£S 18s. yd. , , ■ 



then ~ u ^ — i or is. j±d. At this rate the nett cost per 



ton of the undecorticated cotton cake should not exceed 

 45 J x is. y^d. or ^3 13s. nd. Adding to this the estimated 

 manure value per ton of £1 13s. gd. (Table, p. 225) we arrive 

 at an estimate of ^5 ys. 8d. per ton for the market value of 

 this cake as compared with the decorticated cake at ^8 15s. 

 per ton. 



The results arrived at by either of these methods require 

 to be interpreted with caution, since the composition of a 

 food is only one of several factors which determine what 

 price the purchaser can afford to pay for it. Thus the one 

 requirement which the farmer cannot, as a rule, entirely 

 meet by means of home-grown foods is the all-important one 

 for albuminoids. Carbohydrates abound in all common 

 farm crops; oils can be largely dispensed with if necessary; 

 but albuminoids can only be replaced to a very limited extent 

 by these other ingredients. Hence the farmer enters the 



