STANDARDS FOR RATIONS AND DIETARIES. 209 
accepted by experts in Germany than those of Wolff. Kiihn urges 
the unwisdom of setting up standards asin any wise absolute, 
and calls especial attention to the difficulties in the way of assum- 
ing the composition of feeding stuffs from averages of analyses. 
He insists upon the great values of feeding standards and of 
their use in connection with the estimates of composition of feed- 
ing stuffs, but urges with emphasis the necessity of studying the 
individual animal and fitting the food to the observed needs 
rather than to any arbitrary standard. Wolff, of course, assents 
to these principles in a general way, and would, I am sure, pro- 
test emphatically against considering either his formulas or those 
of Kiihn, or any others, as more than rough approximations and 
averages. 
The following is from comments by the writer upon Prof. 
Kiihn’s article above referred to: 
‘Prof. Kiihn calls attention to several difficulties in the way 
of prescribing definite feeding standards for different classes of 
animals which are fed for different purposes. They have to do 
with the animals, the feeding stuffs, and the commercial value of 
the feeding stuffs and the products. 
“Tn the first place different animals of the same class differ 
greatly in their capacity for utilizing food, and even the same 
animal may require different rations under different conditions. 
Thus different breeds of milch cows and different cows of the 
same breed may vary widely with respect to the amounts of food 
which they can most advantageously utilize. The amount appro- 
priate for 1,000 pounds live weight may be much greater with a 
small cow than with a large one. It varies with the bodily con- 
dition of the animal, whether lean or fat, and with the amount of 
the milk yield. The quantity of food needed depends also upon 
whether, as the milk falls off toward the end of the period of 
lactation, the cow is to be fattened for the butcher or is to be 
used again for breeding and milking. In brief, it is impossible 
to lay down hard and fast rules for quantities of food or quanti- 
ties of nutrients, or for nutritive ratios to apply indiscriminately 
to different animals under different conditions. 
‘“ Again, different specimens of any kind of feeding stuff may 
vary widely in chemical composition so that the figures for average 
composition may be very far from the truth in a given case. The © 
coefficients of digestibility are likewise variable. And even if the 
quantities of actually digestible nutrients in any given instance, 
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