26 THE SCIENTIFIC FEEDING OF ANIMALS 



Since the air had free access to the edges of these compressed masses, 

 much of the material was destroyed or lost by decomposition or decay. 

 To avoid these losses Messmer and Sonderegger put the grasses in the 

 wilted stage into sealed cement reservoirs (or silos) and a Swiss firm has 

 manufactured a patented mechanical press for the purpose (Fig. 10). 



The present-day method is as follows: The grass, freshly mowed, or 

 in a slightly wilted or partially dried condition, is loosely but evenly 

 packed, or layered, into specially constructed silos, having walls of double 

 layers of hollow tile, cement-lined on the inside. The grass is thus piled 

 up from 3}^ to 5 feet high. Within 24 hours the temperature of this mass 

 rises to 122° F. (to be determined by aid of thermometer). 



As already explained, it is important that this temperature be attained, other- 

 wise, at lower temperatures (under 109° F) acetic and butyric acid fermentation 

 will be in excess, and spoil the product. Lactic acid fermentation does not occur 

 except at temperatures above 109° F. This has a sterilizing effect upon the feed 

 and a favorable dietetic effect. 



As a result of oxydation processes (combustion) which occur during fermenta- 

 tion, the mass becomes heated. The amount of heat generated is dependent upon 

 the amount of air that has access, and this can be regulated by compression of the 

 mass. Increased compression checks oxydation and reduces the temperature by 

 shutting off the air, and vice versa. 



When the temperature reaches 122° F. another layer of equal thickness 

 (3j4 to 5 feet) is added loosely, treated as before, and so on until the 

 silo is filled. The topmost layer is then covered with planks and the entire 

 contents of the silo subjected to the pressure of a mechanical hand press. 

 After 4 to 6 weeks the process is completed and the feed is "done," al- 

 though it may be used for feeding purposes before this time. It will keep 

 for one year. If the process of filling the silo is interrupted, the last layer 

 put in should be pressed as above explained, as soon as properly heated. 



Successfully prepared sweet silage or "press feed" has a light green to 

 brown color. Very light green color indicates low temperatures during 

 the process of curing and is attended with the presence of more volatile 

 acids (which is undesirable). The darker the color, the higher the tem- 

 peratures during the curing stage. Too much heating reduces the nutri- 

 tive value of the feed. An olive green color is the most desirable. 



The smell should be neither sour (volatile acids, too low temperatures 

 during fermentation) nor putrid, nor musty (decay and moldiness), nor 

 should it be that of brown hay (from too high temperatures). The odor 

 of good press feed should remind one of that of dried or baked plums! 

 The taste should be only slightly acid. 



The structure of the plants should be preserved. The botanical char- 

 acter of the grasses should still be clearly recognizable, and in contrast 

 to ordinary hay, they should retain all of the smaller and more delicate 

 organs and appendages of the stem and leaves. If the plants are easily 

 broken or crushed the curing temperatures were too high. 



Physically, sweet silage or "press feed" is moist or clammy to the touch 

 and contains about 66 per cent of water and 34 per cent dry matter. The 

 latter is composed of crude protein, 5.25 per cent, of which 2.6 per cent 



