MANUAL OF CATTLE-FEEDIHG. 28? 



necessity of observing a medium nutritive ratio in tlie 

 fodder of farm animals. 



Indeed, a too-wide nutritive ratio may cause more waste 

 tlian a too-narrow one. In the former case the protein 

 consumption is, as we learned in Part I., needlessly in- 

 creased, but the nitrogen of this protein is excreted in the 

 urine, and has its value in the manure. In the second 

 case, a too-wide nutritive ratio also causes a waste of pro- 

 tein by decreasing its digestibility, but it also causes some 

 of the starch to pass throng! i the body without being put 

 to any use, wliile as manure tiie latter is absolutely value- 

 less, containing only elements of which the atmosphere 

 offei-s an inexhaustible snpply to plants. 



Roots. — It will not often be the case in practice that 

 pure starch or sugar is fed, but potatoes and roots, which 

 are especially rich in carbhydrates or pectin substances, 

 must exert a similar influence on the digestibility of coarse 

 fodder. It is to be expected, however, that the resulting 

 depression will be smaller than that caused by pure 

 carbhydrates, since the above-named fodders contain, be- 

 sides starch and sugar (or pectin), other substances, and 

 especially more or less albuminoids. 



The effect of roots and potatoes on the digestibility of a 

 ration has been investigated chiefly at the Ilohenheim Ex- 

 periment Station, where a large number of experiments on 

 sheep have been executed.* 



In calculating the results of these experiments the pota- 

 toes and roots have been considered as wholly digestible, 

 and any decrease in the digestibility of the ration is con- 

 sidered as affecting exclusively the remaining fodder. The 



* Landw. Jahrbucher, VIII. , I. Supplement, p. 123. Compare also 

 Wolff's ''Ernahruiig Landw. Nutztliiere/* pp. 158-175. 



