Phase II
After the oxygen in the ensiled
forage has been utilized by the
aerobic bacteria, Phase II begins.
This is an anaerobic fermentation in
which the growth and development
of acetic acid-producing bacteria
occurs.
These bacteria ferment soluble
carbohydrates and produce
acetic acid as an end product.
Acetic acid production is
desirable because it can be
utilized by ruminants in addition to
initiating the pH drop necessary to
set up the subsequent fermentation
phases. As the pH of the ensiled
mass falls below 5, the acetic
bacteria decline in numbers as
this pH level inhibits their growth.
This signals the end of Phase II.
In forage fermentation, Phase II
lasts no longer than 24 to 72 hours