Effects of a Delayed Harvest and Additives on the Fermentation Quality of Corn Stalk Silage

This study investigated the effects of harvest time, cellulase, lactic acid bacteria, and ensiling with alfalfa hay on the chemical parameters, bacterial community composition, and fermentation of corn stalk silage. Corn stalks were ensiled after the ear harvest at 0 days (D0) and 20 days (D20). Each harvest was treated with alfalfa hay [AL, 5% of fresh matter (FM)], <i>Lactobacillus plantarum</i> (Lp) (1 × 10⁶ CFU/g of FM), <i>Trichoderma</i> cellulase (TC) (100 mg/kg of FM), or both Lp and TC (Lp+TC). The silos were opened after 60 days of fermentation. The dry matter (DM) content of raw materials increased from 18.79% to 28.32% with the harvest time. The acid detergent fiber (ADF) content also significantly increased (<i>p</i> < 0.05), while water-soluble carbohydrates (WSCs) and in vitro dry matter digestibility (IVDMD) significantly decreased (<i>p</i> < 0.05). After 60 days, the neutral detergent fiber (NDF) and ADF contents increased, and all chemical composition and fermentation state parameters of silages had significant differences (<i>p</i> < 0.05) with the harvest time. Compared with the control group, the AL treatment resulted in higher (<i>p</i> < 0.05) DM and crude protein (CP) contents, and the Lp+TC treatment resulted in a lower NDF (<i>p</i> < 0.05) content. For D0, the TC and Lp+TC treatments resulted in a higher WSC content and lower NDF and ADF contents than in D20. Meanwhile, the ammonia-nitrogen (NH₃-N) content in each treatment was less than 10% of the DM. The pH values were all approximately 3.70. The AL treatment significantly increased the lactic acid (LA) content and lactic/acetic acid ratio (LA/AA). Additionally, the silages had a similar microbial environment before and after fermentation. We recommend harvesting corn stalks for silage immediately after the corn ear harvest. Adding cellulase improved the corn stalk feed value, and ensiling with alfalfa hay improved its fermentation quality.