MILK PRODUCTION 329 



431. American feeding standards. Beginning with 

 the feeding standard suggested in 1894 by F. W. Woll 

 for dairy cows, several standards have been proposed by 

 American authors and experimenters. These proposals 

 have been based upon studies of the practice of success- 

 ful feeders, or upon more or less extended feeding experi- 

 ments. It cannot be said that with a single exception 

 these so-called American rations are based upon close 

 physiological studies. They are, in fact, mostly modi- 

 fications and extensions of the Wolff or Wolff-Lehman 

 standard, arrived at through a critical study of what have 

 proved in practice to be productive rations. 



It is well to submit these various commendable and 

 useful efforts to arrive at practical feeding standards to a 

 critical analysis, not only for the purpose of presenting 

 the conclusions reached, but also in order to set forth the 

 limitations that accompany experimental work of the 

 type upon which the conclusions were based. 



432. WolPs standard. This standard is based upon 

 the average of about 100 rations in apparently success- 

 ful use by American and Canadian farmers. From the 

 average was deduced the following daily ration for milk 

 production: Dry matter 24.5 pounds, digestible protein 

 2.15 pounds, digestible carbohydrates and fat 14.5 pounds. 

 This ration is suggested, apparently, on the assumption 

 that what is being done by a group of successful feeders 

 is a safe guide to the practice of others. In a sense this 

 is true, when conditions are similar. This method of 

 reaching a conclusion gives no assurance, however, that 

 the practice observed is the best that could be devised, 

 even though under given conditions it may be found 

 profitable. Such a study of existing practice is suggested, 

 however. 



