§83 MANUAL OF OATTLB-FBEDIKG. 



which Stoliniann lias made the basis of his formula (p. 

 250) for calculating the digestibility of the protein of a 

 ratiou from its chemical compositiou. A large mimber of 

 lesults seem to indicate strongly that this is a general law, 

 of which the experinients cited above are only special 

 cases, and that the non-nitrogenous matters of hay, e, g.^ as 

 truly depress the digestibility of its pj'otein and fibre as does 

 the addition of starch. The only difference is that we can- 

 «iot abstract the non-nitrogenous matters from the hay and 

 observe the digestibility of the other constituents, but 

 must determine the digestibility of the hay as a whole. 



The statement that starch decreases the digestibility of 

 other fodder, then, is simply a practically convenient way 

 of stating the result in this particular case. 



Sugar. — jJ^ot many experiments on the influence of 

 sugar on the digestibility of rations have been made ; but 

 those which have been executed show, as was to be ex- 

 pected, that widening the nutritive ratio of a ration by 

 means of sugar produces essentially the same result as 

 when effected by starch. The decrease in the digestibility 

 appears to be rather smaller, however. 



Effect on Digestibility of Nitrogen-free Extract. 

 — ^Thus fai' we have considei^ed chiefly the effect of 

 easily digestible carbhydrates on the digestibility of pro- 

 tein and fibre. In regard to the nitrogen-free extract and 

 the fat of the coarse fodder, it may be said that the diges- 

 tibility of these constituents is not essentially decreased bj 

 rtwA »r smgiir so long as Hae iMfer are completely di- 

 gested. 



Frequently, however, the starch or sugar not only dimi- 

 nishes the digestibility of the protein and fibre, but escapes 

 digestion itself to a not inconsiderable extent, thus causing 

 a double loss. We have here another indication of the 



