Altering the bacterial community: sour soup decreased CO production and improved the fermentation quality of and mixed silages.

Introduction: Carbon dioxide (CO) generated during the ensiling process is a source of greenhouse gas emissions and a reason for the loss of nutrients during ensiling.

Methods: (B), (T) and their mixtures (B7T3, B5T5 and B3T7) were ensiled with sour soup (S) and (LAB) to investigate the effects of additives on silage quality, CO2 production and bacterial communities.

Results: After 45 days of fermentation, the B3T7 treatment resulted in the lowest CO production, a relatively high lactic acid content (pH < 4.2), and relatively high relative abundances of Lactiplantibacillus and Weissella after fermentation; the quality of silage in all the treatments with additives was greater than that in the CK treatment, and the CO content was significantly lower than that in the CK treatment ( < 0.05). In addition, the overall silage quality was better than that of CK after the addition of additives, the CO content was significantly lower ( < 0.05), and adding sour soup resulted in a greater effect than adding LAB. CO production was positively correlated with the relative abundances of , and and negatively correlated with the relative abundances of , and .

Conclusions: In summary, selecting an appropriate proportion of different forages for mixed silage and adding sour soup may be effective ways to improve silage quality and reduce CO production during ensiling.