COMPOUNDING RATIONS 233 



2 -4 Ibs. of " starch " less than half what is required. On the 

 other hand, 11*2 Ibs. of beans contain the required amount of 

 "starch" and 2'i Ibs. of digestible protein more than double 

 the required quantity of the latter. 



It comes to this, that since the N-ratio of the oats is 6*3 

 to i, and that of the beans is 27 to i, the difference in com- 

 position cannot be reconciled by any means. If two foods 

 have the same N-ratio, they can replace each other in equiva- 

 lent quantities, but otherwise one cannot be substituted for 

 the other without altering the amounts either of nitrogenous 

 or of non-nitrogenous nutrients in the ration. That is, in 

 brief, the whole problem in compounding rations ; the N-ratios 

 of the foods differ from each other, and, as a rule, also from 

 the standards set up. It is, of course, a very rare case that 

 an animal is fed entirely on a single food. More commonly 

 the rations comprise two or three or more different kinds of 

 feeding stuff, and the problem is to combine them in such 

 proportions as to yield the specified amounts of nitrogenous 

 and non-nitrogenous nutrients. 



Two Foods. Any two foods can be combined in one 

 proportion, and in one proportion only, 1 to give any specified 

 amounts of protein and " starch," provided the N-ratio of one 

 of them is closer, and that of the other is wider, than the 

 N-ratio of the specified dietary. That proportion can often 

 be determined more or less accurately by a shrewd guess. 

 Such, probably, is the method adopted by most farmers in 

 practice, and such is the method commonly described in text- 

 books intended for their use. 



Example- -To find what quantities of linseed cake and 

 rice meal should be used in order to produce a specified ration 

 from the following data : 



Per cent. Per cent. 



Linseed cake ..... 25 56 2-24 to i 



Rice meal ...... 6 65 JO'83 ,, i 



Dietary ....... 10 60 6*00 ,, i 



1 In the special case of two foods, both of which have the same 



N-ratio as the specified dietary, they can be combined in any proportion 

 whatever. 



