Effects of molasses interacting with formic acid on the fermentation characteristics, proteolysis and microbial community of seed-used pumpkin leaves silage

Abstract

Ensiling is an appropriate method to preserve high-moisture vegetable wastes, while using additives as regulable supplements for achieving silages with desired quality profiles. The present study assessed the effects of molasses and formic acid on the fermentation characteristics, proteolysis and microbial community during the ensiling process of seed-used pumpkin leaves (SUPLs). Using the following groups: silage without additive (CK), and silage with molasses (M), formic acid (FA) and a combination of formic acid and molasses (FAM). The use of additives decreased the pH value, dry matter loss (DML) and butyric acid content, and improved the levels of lactic acid and peptide-N during ensiling. Furthermore, the lowest ammonia-N content (36.0 vs 48.6 g/kg TN), pH value (4.70 vs 5.47), DML (19.8 vs 220.0 g/kg DM) and the highest level of lactic acid (178.7 vs 34.8 g/kg DM) was observed in FAM on day 60. The combined use of formic acid and molasses increased the Lactobacillus abundance in the initial and terminal stages of fermentation, decreased the Clostridium and Enterobacteriaceae abundances, and the LDA score of Vagococcus and Eggerthella, and the abundance of bacteria that were formed biofilms and potentially pathogenic, and dramatically improved carbohydrate metabolism and amino acid metabolism. In summary, the combined use of formic acid and molasses could serve as a promising strategy for the preservation of SUPLs silage and provide a reference for the clean utilization of other vegetable wastes.