Till: xrrR(){;EX-FRi:]: i-atract of plants Axn fi-edixg 



STUFFS. 



B. TOLLKNS, Ph. D. 

 Director of the .l</riciilliir(il-('lieiiiic((l Lalxiratori/ of the Uiiiversifj/ of (ioitiiifien, 



nermann. 



For many years past the so-called Weende inetbod lias been com- 

 monly used in the experiment stations in Germany and America for 

 determining' the composition of feeding stuffs, and for judging of 

 their value for animal nutrition. The method was devised by the late 

 Prof. W. Henneberg, director of the experiment station at Gottingen, 

 Germany, formerly located at Weende, near Gottingen. By means of 

 it Professor Henneberg showed the fallacy of Thaer's hay-value theory 

 of feeding* stuffs, according to which the value of a feeding stuff was 

 stated in terms of 100 lbs. of meadow hay. 



As is well known, in this metliod the percentages of the ash, j)rotein, 

 fat, and crude fiber are determined by fixed analytical methods, and 

 the sur;i of these and the water, subtracted from 100, gives the so-called 

 nitrogen -free extract. 



As the name imi^lies, Henneberg did not reg'ard this nitrogen-free 

 extract as a distinct, uniform substance, but rather as a mixture. 



It represents that portion of a feeding stuff which is not soluble 

 in ether (fat),^ and does not belong to the nitrogenous (protein) or 

 ash constituents, but is dissolved by the reagents used in determin- 

 ing crude fiber, especially by the dilute boiling acid and alkali. The 

 nitrogen free extract is, therefore, the portion of a feeding stuff soluble 

 in this dilute acid and alkali, less the fat, protein, and ash. It is evi- 

 dent tliat it would include the water-soluble substances, especially 

 tlie sugars and other soluble carbohydrates, such as gnms, inulin, etc. 

 Many other carboliydrates nr(> dissolved in boiling dilute acid, notably 

 starch, mucilages, etc.; and boiling with dilute potassium hydroxid 

 completes the action. 



CONSTITUENTS OF THE NITROGEN-FREE EXTRACT. 



The carbohydrates always constitute a large part of the nitrogen- 

 free extract, and this fact has led .some chenusts to designate it as 



' Besides the true fats, i. e., the glycerids of the fatty acids, this crude fat contains 

 a variety of other substances, for an acconnt of which seo E. Sfhnlze, Landw. 

 Vers. Stat., 15 (1872), p.«l; and J. Kfinig, Landw. Vers. Stat., 13 (1870), p. 241. 



641 



