254 THE CHEMISTRY OF CATTLE FEEDING 



a large amount of carbon dioxide are produced. Pecto- 

 celluloses are probably also resolved first into hydrated cellulose 

 and mucilages, and then into sugars which suffer the same 

 fate as those formed from starch. The lignified celluloses 

 are not known to undergo any change. Any fats that may be 

 present are probably also hydrolysed. 



The extent to which such changes may occur depends 

 chiefly upon two factors, viz. the temperature and the access 

 of air. During the colder months of the year, the changes 

 proceed very slowly, but as the temperature rises with the 

 advance of spring, they are accelerated and a considerable loss 

 of nutrients results. When roots are sliced or pulped a large 

 surface is exposed to the air, and the changes proceed very 

 rapidly ; if piled in heaps, so as to conserve the heat produced, 

 the temperature rises, and if due care is not taken it may 

 become high enough to char the sugars. This method of 

 preparing the food is often resorted to because it is considered 

 that the fermentation if not carried too far renders the roots 

 more palatable to the animals. However that may be, it 

 involves a certain loss of carbohydrates, and it is undoubtedly 

 laborious. Two inferences may be drawn from these facts, 

 namely : (i) Care should be taken not to bruise or cut the 

 roots before storing. Otherwise, the rapid fermentation which 

 sets in owing to the access of air may spread to the whole 

 heap and spoil it. (2) Storing in pits is the more efficacious 

 method, as the air is more thoroughly excluded and a more 

 even, low temperature is maintained. 



Grass, clover, vetches and other succulent herbs when 

 collected together undergo changes similar to those described 

 above, but even more rapidly, and soon become unfit for use 

 as food. If, however, the heaps are very highly packed, so 

 as to exclude the air as far as possible, fermentation is not 

 entirely arrested, but it takes place much more slowly, and 

 the product forms a palatable fodder to which the name of 

 ensilage or more shortly " silage " is generally applied. If 

 made in a heap or " stack," as suggested above, the exterior 

 portion, which is, of course, in contact with the air, becomes 

 charred and unfit for use. In order to prevent this waste of 



