CHAPTER XIV 



COMPOUNDING RATIONS 



Problems. It is obvious that a knowledge of the various 

 matters discussed in previous chapters will be of little prac- 

 tical or theoretical advantage unless the actual foods can be 

 so arranged as to conform to any standard that may be set up. 

 Suppose, for example, that it is desired to feed an animal at 

 the rate of 6 Ibs. of starch (or the equivalent of the same) and 

 i Ib. of digestible protein per day : on looking through the 

 tables giving the composition of the foods probably none will 

 be found that contain the nutrients in exactly that proportion 

 (6 to i). 



On reference to the chart (p. 230), we can readily discover 

 which, if any, of the foods have a nutritive ratio nearest to 

 that required. Of those represented, oats, green clover, and 

 lucerne all lie fairly close to the 6 to i ratio line, and any 

 one of these might be considered near enough for practical 

 purposes in this respect. Assuming that a suitable food 

 having the desired N-ratio were available, it would be a simple 

 matter to calculate what quantity of it should be used. 



A very similar case arises when it is desired to change the 

 food of an animal without altering the amounts of nutrients 

 in the ration. If, for example, beans were to be used in place 

 of oats, consider what quantity of the former could be 

 substituted for, say, 10 Ibs. of the latter. 



The oats contain 9 per cent, of digestible protein and 57 

 per cent, digestible non-nitrogenous nutrients (reckoned as 

 starch), i.e. 0*9 Ib. of the former and 57 Ibs. of the latter in 

 10 Ibs. of the food. The beans contain 19 per cent, of 

 digestible protein and 51 per cent, of "starch"; so 47 Ibs. of 

 beans would contain the required amount of protein, but only 



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