61 



as compared with this unit are expressed in terms of "starch 

 equivalents." 



Armsby expresses the net available energy in therms, one 

 therm being 1000 Calories. 



Both Kellner and Armsby have deduced methods for for- 

 mulating rations on the basis of digestible protein and net avail- 

 able energy. These methods will probably be generally adopted 

 as more expermental data is secured. 



It has been assumed that to a certain extent, the animal is 

 a machine in which definite combinations of nutrients known as 

 feeding standards should be supplied without taking into con- 

 sideration the individuality of the animal nor the particular char- 

 acter of the feedstuffs making up the different rations. The best 

 that any such system will produce is average results. 



Palatability, variety and the effect of food when fed in dif- 

 ferent combinations should also be considered. The importance 

 of variety in a ration may have a chemical significance. For 

 instance, we are only at the beginning of our knowledge of the spe- 

 cific nutritive effect of the different proteins; the protein from one 

 cereal may have a greater feeding value than that from another. 

 Again, one feeding stuff may contain substances not now known 

 to be necessary for the well-being of the animal; hence, the im- 

 portance of variety and the advisability of combining a number 

 of feeding stuffs in the ration. 



There are also economic factors which may lead the feeder 

 to vary more or less from any accepted standard. Where milk 

 or cream must necessarily be sold at a low figure, it may be good 

 business policy for the farmer to use largely of those feeding stuffs 

 that he can produce even though they may not be the best suited 

 for a maximum milk production. 



The object of this article is not to give in detail the various 

 methods of figuring rations, for which the reader is referred to 

 special articles and bulletins, but to call attention to the fact 

 that the study of the principles of nutrition has been progressive, 

 and that we may still be only at the beginning of our knowledge 

 of the subject. It is certain that feeding practice basfed on any 

 standard, be it Wolff-Lehmann, Haecker, Armsby or any of their 

 modifications, will yield more satisfactory results than where no 

 attention is paid to our present knowledge of scientific feeding. 



The assertion sometimes made that much of the work al- 

 ready accomplished is worthless and should be cast aside, is not 

 true. It is not only of practical value but will serve as stepping- 

 stones for future investigators working to increase our knowledge 

 of the rational feeding of farm animals. 



