The purpose of this study was to investigate the effect of different additives on the microbial composition, fermentation quality, and bacterial community structure of big-bale
Leymus chinensis silage. An experiment was set up with four treatment groups: a control (C) group,
Lacticaseibacillus rhamnosus (L) group, molasses (M) group, and
L. rhamnosus + molasses (LM) group, with three replications per group, and
L. chinensis silages were fermented for 20 and 40 days. The lactic acid, acetic acid, 1,2-propanediol, and propionic acid contents increased, and pH, butyric acid, 1-propanol, and ethanol contents decreased in the L, M, and LM groups compared to the C group. In the LM group, the number of lactic acid bacteria was the highest, while the pH was the lowest.
Enterobacter and
Paucibacter were the main dominant genera in the C group. The addition of
L. rhamnosus and molasses increased the relative abundance of
Lactobacillus,
Weissella, and
Enterococcus.
Lactobacillus abundance correlated positively (
p < 0.01) with
Lactococcus,
Enterococcus, and
Weissella and correlated negatively with
Enterobacter and
Paucibacter. Conversely,
Enterobacter and
Paucibacter showed a strong positive correlation (
p < 0.01, R = 0.55) during fermentation.
Lactobacillus,
Enterococcus, and
Weissella were positively associated (
p < 0.01) with acetic and lactic acid levels, while
Enterobacter abundance was correlated positively (
p < 0.05, R = 0.43) with 1,2-propanediol content. In summary, the addition of both
L. rhamnosus and molasses improved the fermentation quality and bacterial community structure of big-bale
L. chinensis silage. In addition to inhibiting harmful microorganisms, this combination improved the fermentation products of big-bale
L. chinensis silage through microbial regulation.
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