J. Alan Murray 101 



a repetition of the statement in different terms, because, if true, it would 

 be equally applicable to an animal producing milk. 



The starch equivalent system is still on trial, and it is tolerably 

 evident that it is far from perfect. It is complex in definition and 

 difficult to apply. Farmers as a rule will have none of it, and it frequently 

 proves a stumbling-block to scientific students. It may even betray 

 experts as it has on occasion betrayed Kellner himself. The system 

 originated in a jjraiseworthy attempt to overcome some of the more 

 obvious objections to the old-fashioned "feeding standards" in which 

 it was assumed that the nutrients in all kinds of foods were of equal 

 value for all kinds of purposes. At least it is in that direction that it 

 has found its chief application. The foregoing discussion, however, 

 tends to show that the day of such feeding standards is over. Attempts 

 to calculate a ration comprising two or more independent variables, 

 e.g. maintenance and fattening, by a single arithmetical operation — 

 the rule of three — which it now appears is not applicable to either 

 are no longer defensible. Conversion of the nutrients into starch 

 equivalents does not overcome this difficulty. 



Animals re(piire food for maintenance and for the several forms 

 of production — growth, work, fattening, and lactation — though it 

 rarely happens in practice that more than two, or at most three, out 

 of these five conditions have to be satisfied at the sanui tinu^ in any 

 given case. The best results will, therefore, be obtained when the 

 digestible nitrogenous and non-nitrogenous nutrients are supplied in 

 the proportions and quantities required for each specific purpose. 

 The amounts required for maintenance depend upon the size of the 

 animal and those for other purposes upon the rate of each kind of 

 production, though probably in no case are they directly proportional 

 to that rate. In each case the nutrients must be derived from a food 

 suitable for the purpose. For exanrple, the nutrients for maintenance 

 of oxen should be derived from cheap coarse fodders, and those for 

 fattening from the finest, nrost readily digestible materials. Nothing 

 should be deducted from the former for the work of digestion, etc. 

 From the latter there is nothing to. deduct on this account. At least, 

 except in one or two instances, the amount to be deducted is insignificant. 

 If, however, the amounts of nutrients for the several purposes are not 

 to be added together but directly translated into the corresponding 

 amounts of appropriate kinds of food, it seems clear that they nnist 

 be determined by a separate calculation in each case, and the raison 

 d'etre of the starch equivalent system disappears. 



