468 IOWA DEPARTMENT OF AGRICULTURE 



The greater part of the past two years has been spent by the writer 

 in an effort to settle this much discussed question. The results obtained 

 show definitely that neither bacteria alone nor plant enzymes alone are 

 responsible for the fermentation of silage.f 



It has been found that a plant enzyme digests the starch and gives a 

 preliminary increase in some cases to the sugar content. Another 

 enzyme breaks down cane sugar into simple sugars. The acid-forming 

 bacteria are the agents which form most of the acid from the sugar. 

 This statement is supported by the fact that bacteriologists have found 

 large numbers of acid-forming bacteria in silage. Part of the alcohol 

 IS formed by the plant enzymes and more alcohol is formed later by yeasts,| 

 which are microscopic one-celled plants like bacteria. Some of the pro- 

 tein is digested by plant enzymes and some by bacteria. Both plant 

 enzymes and bacteria seem to have a share in the production of the heat 

 which raises the temperature of silage. The evolution of carbonic acid 

 gas, which is formed in such large quantities at the beginning of the 

 fermentation, seems to be due largely to the plant enzymes, although the 

 bacteria and yeasts doubtless furnish part of it. 



Direct evidence has been found of an enzyme called invertase which 

 hydrolyses or breaks down cane sugar, and of an enzyme called zymase, 

 which forms alcohol from sugar. Other investigators have found enzymes 

 in the corn plant which act on sugar and on proteins. Enzymes of sim- 

 ilar nature have been found in practically all plants, as they are the 

 agents which promote plant growth. Additional evidence has been ob- 

 tained by fermenting silage and even corn juice in the presence of anti- 

 septics, showing that plant enzymes are active in silage fermentation, 

 but that they are not the only active agents in the process. 



SOFT CORN EAR SILAGE. 



In the fall of 1915, the unusually large amount of "soft corn" that 

 was harvested, owing to the unfavorable season and early frosts, pre- 

 sented a rather difficult problem in Iowa. Much of the corn grain was 

 so immature and contained so much moisture that it could not be safely 

 cribbed, but would mold and be a total loss unless preserved in some way. 

 The proportion of the average total crop that could be preserved in the 

 ordinary way in the available silo space was small. Therefore the ques- 

 tion arose as to the possibility of preserving the ears alone in the silo, 

 without the stover. 



The writer, in cooperation with John M. Evvard, assistant chief of 

 the animal husbandry section of the Iowa Agricultural Experiment Sta- 

 tion, ensiled soft corn ears successfully in small laboratory silos. Silage 

 made in these silos is identical in quality and composition with properly 

 made silage in a farm silo. The ears, which were in late roasting stage, 

 were husked, run through a silage cutter which cut them into one-half 

 and one-inch pieces, and tightly packed into large cylindrical glass jars. 



tA detailed account of these experiments is to be published later. 

 JTeasts are the cause of ordinary alcoholic fermentation in beer and 



