226 THE CHEMISTRY OF CATTLE FEEDING 



factor commonly used is 2-3; but in more exact calculations 

 it should be 2*5 for oily seeds and cakes, and 2*2 for hay, straw, 

 and coarse fodders generally. The intermediate number may 

 be used for cereal and other grains. 



The following example will serve to illustrate the method 

 of working out the nutritive ratio of a food (bran) from the 

 given data : 



Total Digestibility p 

 nutrients, coefficients. 



Fat 4 X 075 x 2-3 = 6-9 



Soluble carbohydrates . . 56 X cr8o = 44-8 



Fibre 9 X ' 2 = I P 8 



Total non-nitrogenous nutrients as starch . 53^5 

 Protein 14 X 075 = 10-5 



The ratio is, therefore, 53*5 to io'5, or 5'i to i. 



The ratio of the total protein to non-nitrogenous nutrients 

 without reference to their digestibility, is of no value whatever. 



A low N-ratio, say 5 to i, is generally described as close 

 or narrow; and higher ratios, say 10 to i, are said to be wide. 



The N-ratios of the foods are of considerable importance 

 in judging of the suitability of the food for any specific purpose, 

 also whether one food can be used to replace another, 

 and, if so, in what relative quantity. They are used also in 

 some of the calculations involved in compounding rations 

 from two or more different foods. 



Pecuniary Values. There is no direct relation between 

 the market prices of feeding stuffs and their agricultural 

 (nutritive) value. The former is regulated, like that of all 

 commodities, in accordance with the laws of supply and 

 demand. The latter depends upon the amounts and digesti- 

 bility of the nutrients. It is true, in general, that there is a 

 greater demand for those foods which are of greater nutritive 

 value, but the price, it has been said, depends not on this 

 alone, but also, in part, upon the supply. Thus it happens 

 that one food may be much cheaper or dearer than another 

 even at the same price. Farmers, therefore, would be well 

 advised, when purchasing feeding stuffs, to consider what 



