Adding WSC, such as molasses (Yokota et al. 1991), glucose (Tamada et al. 1999)
and wheat bran to fresh PV at ensiling, may provide greater
fermentation quality. To increase WSC content of PV
silage, WB was added in the present study, which contained
149.5 g kg-1 FW WSC (Table 1). The result indicated
that the WB treatment had more striking effect on
the fermentation quality of PV silage than LAB addition.
Compared with the control, LA concentration of the silage
in the WB treatment increased 6.1 and 3.6 times and pH
reduced to less than 5.0 in two years (Table 2), but spoilage
organisms were not inhibited completely in the silage,
which had high concentration of AA, BA and NH3-N/TN
ratio as well as extensive proteolysis. These observations
clearly illustrated that WSC was not the only limiting factor,
but the lack of epiphytic LAB populations was not in excess
of minimum for good-quality silage. Using LAB+WB
at ensiling reduced pH again compared with LAB or WB
addition, but the pH value was still higher than the critical
level of pH 4.2 (Yang et al. 2004), which associated with
loss of nutritional values. Therefore, PV was generally
high in moisture content and BC, which limited pH reduction
during silage fermentation.