24"^ Jk THE SCIENTIFIC FEEDING OF ANIMALS 



vC^ rms, etc. At the expiration of six weeks the fermentation and drying 

 -*v^^C^process is completed and the product is an air-dried, aromatic, compact 

 l^r , *^ mass, of light brown color, pungent odor and good keeping qualities (so- 

 1, called brown hay), which is relished by animals. 



»^ The losses of nutrients occurring in this mode of preparing hay amount 



to 15 to 30 per cent. They are confined chiefly to the carbohydrates (as 

 high as 45 per cent of these) and to some extent the crude proteins and 

 fats. In addition to this loss, the digestibility of the proteins is impaired. 

 The extent of the losses depend in a measure on the size of the stacks. 

 The losses are considerably less in the stacks customarily built in northern 

 Germany (about 10 or 12 feet in diameter) than in those of southern Ger- 

 many, where they are made twice this diameter. The digestibility of the 

 albumins is also impaired. The plant tissues in this form of hay are very 

 friable and easily crushed between the fingers. 



c. Sweet Silage 



The term "sweet silage" is applied to succulent forage that has under- 

 gone a process of auto fermentation and heating to a marked degree. Any 

 green succulent forage plants are suitable for the preparation of sweet 

 silage; e. g., grass, clover, Indian com, beet leaves and tops, carrots and 

 turnips. 



The character of the products of fermentation is dependent upon the 

 temperature at which the latter takes place. 



1. Acetic acid fermentation takes place at a temperature of 65° to 95° 

 F. In the production of sour ensilage this form of fermentation is usually 

 not unimportant in its effects. The acetic acid bacteria are destroyed at a 

 temperature of 122° F. 



2. Butyric acid fermentation occurs at temperatures between 95° and 

 98.6° F., under anaerobic conditions (absence of oxygen). The spores 

 of these bacteria are very resistant to the action of heat. Butyric and 

 other volatile fatty acids are easily recognized by their disagreeable rancid 

 odor. 



3. Lactic acid fermentation takes place at temperatures between 86* 

 and 149° F. This is the character of fermentation most desirable in all 

 feeding stuff fermentations. In order that this form of fermentation may 

 take place without interference by those less desirable, it should take place 

 between 122° and 149° F. Compared with the sour odor of acetic acid 

 and the rancid smell of butyric acid, lactic acid is practically odorless. 

 The most important lactic acid bacteria are Bacillus delbruecki (warm 

 milk lactic-acid bacillus) and B. cucumcris fermentati and Bacterium 

 lactis acidi (cold milk lactic-acid bacteria I and II). 



In the production of sour silage (common silage) not only lactic acid 

 but a large amount of acetic acid is formed. This is the cause of the sour 

 smell of ordinary silage, hence its name. When the preparation of sweet 

 silage is properly conducted, no acetic nor butyric acids are formed, but 

 only lactic acid. Sweet silage therefore has no sour smell, but rather a 



