Improving silage characteristics in high-moisture grape residues using cotton stalk as a moisture regulator

Grape branches and leaves are promising feedstock for high-quality silage, yet their high moisture content limits effective fermentation. This study aimed to investigate the effect of cotton stalk addition on fermentation quality and microbial characteristics of high-moisture grape branches and leaves silage, providing a basis for the efficient utilization of these resources as animal feed. The experiment included six treatments with different levels of MG (cotton stalk) : 0% (MG0), 10% (MG10), 20% (MG20), 30% (MG30), 40% (MG40), and 50% (MG50). After 60 days of silage fermentation, increasing MG proportion significantly reduced silage moisture content (P < 0.05), while pH and acetic acid (AA) levels significantly increased (P < 0.05). Bacterial community analysis revealed that the dominant genera were mainly Lentilactobacillus, Bacteroides, unclassified_rumen_bacterium, and Romboutsia. Among these, Lentilactobacillus predominated in MG20 group, with a relative abundance of 92.15%. Correlation analysis indicated that Lentilactobacillus was significantly negatively correlated with potentially undesirable bacteria such as Romboutsia and unclassified_Clostridia_UGG_014 (P < 0.01). Network analysis showed that addition of MG altered the bacterial community structure, with MG20 group exhibiting the highest mean degree and graph density, suggesting enhanced microbial interactions. In conclusion, incorporating cotton stalk can significantly improve fermentation quality of high-moisture grape branches and leaves silage while optimizing its microbial community. The best fermentation performance was achieved with 20% cotton stalk addition.