10 BtJLLETIlT 953", U. S. DEPARTMENT OF AGRICULTURE. 



TEMPERATURE AND COLOR CHANGES. 



The changes that occur in corn during fermentation in the silo have 

 been the subject of much study by numerous investigators, both in 

 this country and in Europe. First, there is a more or less rapid rise 

 in temperature of the silage mass, the degree of which depends 

 somewhat upon the temperature of the outside air and more perhaps 

 upon the state of maturity of the corn and the degree of fineness to 

 which it is cut. This is followed by a gradual decline in temperature 

 of the silage and a change of color from the green of the fresh-cut 

 corn to a greenish-brown. These changes in physical appearance are 

 accompanied by a copious evolution of carbon dioxid and the forma- 

 tion of volatile and nonvolatile acids, which have been shown to con- 

 sist largely of acetic and lactic acids. The sugars both of the reduc- 

 ing and nonreducing type which are present in green corn disappear 

 almost completely during the fermentation process. A large part 

 of the albuminoid nitrogen disappears, and there is a great increase 

 in the amount of nonprotein nitrogen, some of which appears as 

 amino acids. 



The causes which produce these profound changes have been the 

 subject of considerable dispute, some writers taking the ground that 

 bacterial action is entirely responsible, others that bacteria have little 

 if anything to do with them, and still others contend that the changes 

 are due in part to bacterial and in part to enzymatic action. 



DOWNWASH OF SOLUBLE MATERIAL. 



The results of the chemical analyses as given in the tables show 

 many evidences of a downwash of soluble material, the upper part of 

 the silo losing and the lower part gaining. In 1914—15 about 2,600 

 pounds of juice were collected, and in 1915-16 about 10,000 pounds. 

 Doubtless had this juice not been allowed to escape, the analytical re- 

 sults for the bags in the lower part of the silo would have shown a 

 greater loading up with soluble constituents, or at least smaller losses. 

 Especially is it believed that this would have been true in 1915-16 

 when the loss in juice rose to almost 5 tons. A difficulty in controlling 

 conditions is the impossibility of removing the bags simultaneously so 

 that they would all have been in the silo the same length of time. 

 This factor might be quite important in the 1915-16 work, when 

 from 1 to nearly 3 months elapsed between the recovery of several of 

 the bags. 



The tables showing losses and gains of green matter and of moisture 

 during ensiling show by comparison the marked effect of adding water 

 when filling the silo. Indeed, the tendency of certain soluble con- 

 stituents to wash downward in the silo, which was probably obscured 

 the second season by the excessive outflow of juice, may have been 



