226 BOARD OF AGRICULTURE. [Jan. 



is wasted ; the ration is improperly proportioned or balanced. 

 The most important point in the balancing of a ration is to 

 secure the proper relation between the nitrogen-containing 

 nutrient (proteine) and the carbon-containing nutrients (fat 

 and carbohydrates) . It is convenient to express this relation 

 concisely, and for this purpose the term nutritive ratio has 

 been adopted. The nutritive ratio may be defined as the 

 ratio existing between the total digestible nitrogen-containing 

 nutrients and the total digestible carbon-containing nutrients. 

 For convenience, the first term of this ratio is usually reduced 

 to unity ; e. g. , 1 : 4 or 1 : 3, etc. 



The determination of the nutritive ratio would be a very 

 simple matter, if all the carbon-containing nutrients were of 

 equal value ; but they are not. The digestible nitrogen-free 

 extract and the crude fibre are regarded as of equal value ; 

 but the digestible fat is more valuable, pound for pound, 

 than they. It is generally estimated that one part of fat is 

 equivalent to two and one-half parts of carbohydrates. The 

 reason is because their heat-producing capacities when 

 burned are in that proportion. One pound of fat generates 

 as much heat when burned as two and one-half pounds of 

 carbohydrates. The first step, then, in the computation of 

 the nutritive ratio, is to combine the fat and carbohydrates. 

 My meaning will be clear from an example. Let me take 

 skim-milk. This contains, in its dry matter: crude ash, 

 6.67 per cent; crude fat, 2.78 per cent; crude proteine, 34 

 per cent ; and nitrogen-free extract, 56.55 per cent. Then 

 fat 2.78 X 2.5 = 6.95 -}- carbohydrates 56.55 = 63.5 total 

 carbohydrates. Then we have the ratio : proteine 34 : 63.5 r= 

 (reducing to unity by dividing by 34) 1 : 1 .87, which is the 

 nutritive ratio of skim-milk of the stated composition. Two 

 more expressions often heard or met with must be defined, 

 and we shall be ready to apply the principles which I have 

 been exjilaining. These are "narrow nutritive ratio " and 

 " wide nutritive ratio." A narrow nutritive ratio is one in 

 which the carbohydrates (expressed by the second number 

 of the ratio) do not much exceed the proteine (expressed l)y 

 the first number of the ratio) ; e. g., 1 : 2 or the ratio of 

 skim-milk just computed; viz., 1:1.87. A wide nutritive 



