FOODS. 85 



the animal for hay and straw is much diminished. Oil 

 supplied in moderate quantities is itself entirely digested. 

 An addition of starch or sugar to a diet of hay or straw, 

 diminishes its digestibility, if the amount added exceeds 

 10 per cent, of the dry fodder. The albuminoids of the food 

 suffer the greatest loss of digestibility under these circum- 

 stances ; the fibre also suffers in digestibility if the amount 

 of carbo-hydrate added is considerable. When starch has 

 been added, it is itself completely digested if the al- 

 buminoid ratio of the whole food is not less than 1 : 8.* 



These facts are of considerable practical importance. 

 Nitrogenous foods, as oilcake and bean meal, may be given 

 with hay and straw chaif without affecting their digesti- 

 bility ; but foods rich in carbo-hydrates, as potatos and 

 mangels, cannot be given in greater proportion than 15 

 per cent, of the fodder (both reckoned as dry food) with- 

 out more or less diminishing the digestibility of the latter. 

 This decrease in digestibility may, however, be counter- 

 acted in great measure by supplying with the potatos or 

 mangels some nitrogenous food. When this is done the 

 proportion of roots or potatos may be double that just 

 mentioned without a serious loss of digestibility. Potatos 

 exercise a greater depressing effect on the digestibility of 

 hay than roots, starch being more potent in this respect 

 than sugar. The cereal grains are rich in starch, but 

 contain also a fair proportion of albuminoids ; they may 

 be added to dry fodder without seriously affecting its 

 digestibility, if the albuminoid ratio of the whole food 

 does not fall below 1 : 8.* 



Common salt is well known to be a useful addition to 



* In this statement made by Wolff the whole of the nitrogen in the food 

 is reckoned as albuminoid. 



