224 



Concentrated Feeding-stuffs. [june, 



parable with those followed in the valuation of manures (see 

 Leaflet No. 72). "Unit" prices for albuminoids, fats, and 

 carbohydrates have been calculated from the market prices 

 of different foodstuffs, and these have then been used for 

 valuation purposes. The system proves far more unreliable 

 in its application to feeding-stuffs, however, than in the case 

 of manures, owing to the fact that, unlike the latter, the 

 market prices of different foodstuffs are regulated with but 

 little regard to their composition. For this and other reasons 

 the direct method has been generally abandoned in favour 

 of the comparative method in which the value of a foodstuff 

 is estimated by comparison with the price at which another 

 of similar character and known composition can be obtained. 



Two such methods are explained below, the first of which 

 can claim little scientific basis, but is found to work fairly 

 well in practice, and is commonly used, whilst the second 

 method is more scientific but more complicated. 



First Method. — For the purposes of the comparison it is 

 assumed that digestible albuminoids and fats are worth 

 2 J times as much as digestible carbohydrates. The percent- 

 ages of digestible albuminoids and oil are therefore added 

 together and their sum multiplied by 2J. To the figure thus 

 obtained is added the percentage of digestible carbohydrates, 

 and the total is referred to as the number of "food-units" 

 in the material. The price of a food-unit in one particular 

 foodstuff is then ascertained by dividing its price per ton by 

 the number of food-units contained in it. This "unit-value" 

 can then be used as a standard by which to gauge the value 

 of other similar foodstuffs of known composition. The fol- 

 lowing examples will illustrate the method. 



Example I. — Suppose that two linseed cakes are offered 

 with the guaranteed compositions and at the prices stated — 



A. B. 

 Albuminoids 32 per cent. 28 per cent. 



Oil 11 9 „ 



Sol. Carbohydrates 34 35 



Price per ton £9 £$ 10s. 



The numbers of food-units in each cake will be as 

 follows : — 



Cake A (32 + 11) x 2\ + 34 = 1414, or say, 141 

 Cale B (28 + 9) x 2| + 35 = 127$, 127 



