SUCCULENT AND WATERY FOODS 255 



fodder, the material is sometimes placed in a pit called a 

 silo dug in the ground ; but as these silos must be lined with 

 cement or other material impervious to moisture, the expense 

 is greater than that involved in the waste of fodder when the 

 silage is make in a stack. Silos are also sometimes built 

 above ground. These are much more convenient but more 

 expensive. 



Whichever method is adopted, fermentation sets in very 

 radidly, the temperature rises, large amounts of carbon dioxide 

 are evolved and great loss of nutrients ensues. This loss of 

 course falls most heavily upon the more readily soluble, i.e. the 

 most digestible constituents, and it may amount to from about 

 a quarter to nearly half of the total organic matter. Further, 

 much of the protein which is not entirely lost is greatly depre- 

 ciated in value by being split up into amino-acid bodies. As 

 against this, however, may be set the fact that some of the 

 lignified, or partially lignified celluloses are also acted upon 

 and probably rendered more readily digestible. 



The loss of nutrients in making ensilage can be reduced to 

 a minimum by tightly packing the material as the stack is built 

 up, and then applying great pressure on the top. Under these 

 conditions the fermentation which takes places is largely of 

 the butyric type, and the product has a disagreeable rancid taste 

 and an extremely offensive odour. It is called " sour silage " 

 in contradistinction to the so-called " sweet silage," which is 

 produced when the stuff is more loosely packed and pressure 

 is not applied until the temperature has risen to about 70 C. 1 

 This inhibits the action of the butyric ferments, and the 

 fermentation which occurs is mainly of the alcoholic and lactic 

 types. The product has a not unpleasant " winey " taste and 

 smell, and is much more palatable. This method is. therefore 

 to be preferred, but it involves a much greater waste of 

 material. A semi-sour or semi-sweet silage is produced at 

 intermediate temperatures, i.e. about 55 to 60 C., and the 

 loss by fermentation is correspondingly reduced. Sour silage 

 has a highly laxative effect and is apt to produce scouring. 



1 At higher temperatures the substance chars. 



