BACTERIOLOGICAL AND CHEMICAL STUDIES OF DIF¬ 
FERENT KINDS OF SILAGE 
By Charles A. Hunter , 1 Bacteriologist , Pennsylvania Agricultural Experiment 
Station 
INTRODUCTION 
The aim of this investigation was to study the nature of the fermenta¬ 
tions taking place in silage composed of a mixture of silage crops. The 
investigation was occasioned by the fact that there seems to have been 
considerable disagreement in the conclusions drawn by different inves¬ 
tigators. Through a review of the literature it was noted that plant 
enzyms were first thought to be the important factors. Recently it 
has been shown that microorganisms appear to play an important part. 
Those who favor this latter conclusion claim that the production and in¬ 
crease in acidity are caused by bacterial action. Still more recently 
some investigators have stated that fermentations were due to the com¬ 
bined action of plant enzyms and microorganisms and that the former 
of these was the more important factor. 
It is definitely known that as silage fermentations take place there is 
an increase in the volatile and nonvolatile acids and ammonia nitrogen. 
It has been claimed that the hydrolsis of protein is first caused by enzyms 
and later by microorganisms. 
Com, kafir corn, cane, corn stover, alfalfa, and alfalfa with a carbo¬ 
hydrate supplement have all been used to make the silage upon which 
different investigators have worked. In a search of Experiment Station 
literature the author was unable to find that any bacteriological and 
chemical studies had been made on silage composed of a mixture of silage 
crops. It was therefore deemed desirable to study two of the most com¬ 
mon silage mixtures now used on Pennsylvania farms—Canada field peas 
with oats and corn with soybeans. The nature of fermentations in 
silage made from these two mixtures was studied in the seasons of 1918 
and 1919. 
REVIEW OF LITERATURE 
Babcock and Russell (r, 2) 2 found that silage would undergo fermenta¬ 
tion even when treated with chloroform, ether, and benzene which inhib¬ 
ited the growth of microorganisms. They found also that the amount 
of heat and acids increased and concluded that this was the result of 
intramolecular respiration. E. J. Russell ( 16 ) came to nearly the same 
conclusion as Babcock and Russell in deciding that plant cells and 
1 Special credit is due Prof. S. I. Bechdel, of the Department of Dairy Husbandry, who stored the crops 
in the large silos, assisted very materially in the securing of the representative samples as they were needed 
from time to time, helped make the determinations of the total and volatile acids, and gave invaluable 
assistance in preparing the manuscript. 
2 Reference is made by number (italic) to “ Literature cited,” p. 788-789. 
Journal of Agricultural Research, 
Washington, D. C. 
ze 
(767) 
Vol. XXI, No. 10 
Aug. 15, 1921 
Key No. Pa.-ia 
