284 



MANUAL OF OATTLE-FEEDIN-G. 



grounds wliicli justify tlxis assumption are two: first, it is 

 known that these feediug-stuffs are very completely if not 

 ■wholly digested, and that large amounts of starch or sugar 

 do decrease tlie digestibility of a ration ; second, with our 

 present knowledge this method of expressing the results is 

 the most convenient for practical purposes. It should 

 never be forgotten that investigations of this sort are of a 

 practical and not a physiological nature. In feeding, it is 

 not the digestibility of one feeding-stuff so much as that of 

 the whole ration which is of importance, and hence that 

 method of expressing the results of digestion experiments 

 is best which attains this end by the simplest method con- 

 sistent with accuracy. Probably roots are not wholly 

 digestible, but at present it is not possible to calculate di- 

 gestion coefficients for them as has been done for the other 

 bye-fodders. 



Calculated on this basis, these experiments yielded, in 

 general, the same results as those on the feeding of starch 

 and sugar, viz. : that tlie depression of the digestibility was 

 greatei', the larger the amount of the bye-fodder and the 

 wider the nutritive ratio. The following table by Wolff, 

 in which the results are grouped according to the propor- 







Dkpeession 



— Peb cent. 





Diy matter of bye- 

 fodder m per cent, of 

 coarse fodder. 



Protein. 



Kitro^en-f ree extract. 



Organic subPtanco. 





Potatoes. 



Roott. 



Potatoes. 



Boots. 

 %.2 



Potatoes. 



Roots. 



12 to 18 



7.3 



4.0 



5.3 



4.4 



3.0 



23 to 35 



13.9 



7.1 



6.5 



4.7 



7.5 



5.9 



44 to 51 



27.8 



11.9 



14.7 



6.8 



17.1 



9.3 



64 to 95 .... 



40.2 



22.3 



13.9 



10.2 



17.5 



11,7 



