120 THE STOCKFEEDER'S COMPANION 



It will be observed that this ration, which has 

 satisfied the Approximate method and the Danish 

 method, is found to be a little too low in digestible 

 albuminoids when the scientific method is employed. 

 If, however, the decorticated cotton cake were increased 

 by \ Ib. per head per day, the digestible albuminoids 

 would be raised to 2-63 Ibs. ; the whole ration would 

 then supply the requirements of the Kellner standard. 



The farmer will, as a rule, find that the approximate 

 method, which is much the simplest, will generally be 

 sufficient for his purpose. 



XVIII. VALUATION OP FOODS. 



It is very difficult to devise a satisfactory method 

 of valuing foods, seeing that they vary so much in 

 composition and digestibility. The value of the food 

 to the animal must be taken in conjunction with the 

 value of the manurial residue, if its real value is to 

 be obtained. Even when all these are taken into 

 account, and the food valued accurately from its chemical 

 constituents, there are such important things as palat- 

 ability, laxativeness, etc., for which it is difficult to fix 

 a proper value. 



The " Food Unit " system values the food from 

 its chemical composition alone, without considering its 

 digestibility ; while the second system takes into con- 

 sideration the food which is retained by the animal 

 body, and makes allowance for the manurial residue. 



(a) Food Unit System. The method employed in 

 obtaining the number of " food units " in a food, is by 

 multiplying the actual percentage of albuminoids and 

 oil by 2j, and adding these results to the percentage of 

 carbohydrates. The total then represents the number 



