DIGESTIBILITY OF FOOD. 69 



With regard to this point, it may be remarked that age has 

 an influence on the digestibility of plants and herbage. Thus, 

 hay cut as soon as ripe is digested more easily than at a later 

 stage of growth, and it is the same with clover. When young, 

 plants contain more albuminoids, and less woody fibre or 

 cellulose, than when old. Boots, however, such as carrots, 

 turnips, potatoes, and mangolds, have their nutritive value 

 increased by age, since the production of the carbo-hydrates 

 as sugar and starch increases with growth. 



Food containing a large amount of nutriment in small 

 bulk is usually digested better than hay or straw. This is 

 particularly the case with the albuminoids and fats contained 

 in them ; 85 per cent, of beans and 80 per cent, of linseed are 

 digested as easily as 64 per cent, of hay and 45 per cent, of 

 straw. The more nitrogenous the hay and straw, the better it 

 is digested. Only 20 per cent, of wheat straw is digested, 

 against 76 of lucerne hay. What is called "cellulose" is 

 usually fairly well digested. Hay and straw of leguminous 

 plants, as peas and beans, are not so easily digested as that of 

 the cereals, because more woody matter, which is indigestible, 

 is contained in the former than the latter. With wheat- straw 

 chaff, it has been stated that about 22 per cent, of the total 

 organic matter in it is digested. 



It would appear that only a certain amount of each 

 substance can be digested from a given quantity of food, and 

 rest or work will not cause an animal to digest more, though 

 it may happen that two animals of the same breed will digest 

 different quantities of the same food. 



The digestibility of one food may be increased by the addition 

 of a second or third different kind, and a decrease in digesti- 

 bility may be effected in the same way. Small quantities of 

 oil added to a diet of hay and straw will slightly increase 

 their digestibility ; but the addition of sugar or starch, if it ex- 

 ceeds 10 per cent, of the diet (both being dry), diminishes the 



