FERTILIZER CONTROL STATION. 331 



Digestibility of Potatoes. 



Many tables giving the digestibility of feeding staffs mention 

 no coefficients of digestibility for tubers and roots, on the ground 

 that they can be considered as practically completely digestible. It 

 is not clear why this distinction is made in the case of tubers and 

 roots when corn meal or some of the concentrated bve-fodders are 

 but little if any less disfestible. 



Again, the conclusion was reached some time since by German in- 

 vestigators that the effect of feeding large quantities of tubers or 

 roots in connection with coarse fodder is to seriously depress the di- 

 gestibility' of the coarse fodder, especiallj' of the protein and crude 

 fiber. Recent investigations in German}^, and some limited experi- 

 ments made at this Station, seem to warrant a doubt whether this 

 conclusion should not be modified. 



The above considerations are discussed more fulh- on subsequent 

 pages. In this connection there are only given the figures reached 

 for the digestibilil}- of the potatoes by the method adopted. These 

 digestion trials with coarse fodder and potatoes were made for the 

 purpose of studying the so-called depression of digestibility of the 

 coarse fodder due to the potatoes, and not for the simple purpose of 

 ascertaining the digestibility of potatoes, for in the latter case the 

 method of procedure would have been different. The figures reached 

 are undoubtedly somewhat too low for all the constituents of the po- 

 tatoes, especially for the protein. 



In these trials the plan adopted was to feed with the potatoes one 

 of the coarse fodders, the digestibility of which had previously been 

 determined by feeding to the same animals. Knowing the digesti- 

 bility of the total ration, and of one of its constituents, viz., the 

 coarse fodder, it is possible to calculate the digestibilitj' of the po- 

 tatoes. Trials were made with two sheep, Nos. 1 and 2, using oat 

 straw and potatoes, and with sheep No. 2, using Timothy hay and 

 potatoes. The analyses of these foods are given previously, Nos. 

 XXVU, XXXllL XXX and XXXII in the table of fodder analy- 

 ses. 



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