Effects of lactic acid bacteria and molasses on fermentation dynamics, structural and nonstructural carbohydrate composition and in vitro ruminal fermentation of rice straw silage

OBJECTIVE: This study was to evaluate the fermentation dynamics, structural and nonstructural carbohydrate composition and in vitro gas production of rice straw ensiled with lactic acid bacteria and molasses. METHODS: Fresh rice straw was ensiled in 1-L laboratory silos with no additive control (C), Lactobacillus plantarum (L), molasses (M) and molasses+Lactobacillus plantarum (ML) for 6, 15, 30, and 60 days. After storage, the silages were subjected to microbial and chemical analyses as well as the further in vitro fermentation trial. RESULTS: All additives increased lactic acid concentration, and reduced pH, dry matter (DM) loss and structural carbohydrate content relative to the control (p<0.05). The highest organic acid and residual sugar contents and lignocellulose reduction were observed in ML silage. L silage had the highest V-score with 88.10 followed by ML silage. L and ML silage improved in vitro DM digestibility as compared with other treatments, while in vitro neutral detergent fibre degradability (IVNDFD) was increased in M and ML silage (p<0.05). M silage significantly (p<0.05) increased propionic acid (PA) content and decreased butyric acid content and acetic acid/PA as well as 72-h cumulative gas production. CONCLUSION: The application of ML was effective for improving both the fermentation quality and in vitro digestibility of rice straw silage. Inclusion with molasses to rice straw could reduce in vitro ruminal gas production.