The wilting process is required for the preparation of traditional low-moisture silage, which is not only subject to the interference of rainfall during the harvest season in many areas, but also increases labor, economic, and time costs. Therefore, in this experiment, newly harvested alfalfa was supplemented with a complex additive consisting of lactic acid bacteria (LAB), sucrose, and corn flour, and then ensiled directly in order to explore a suitable high-moisture silage processing method. There were four groups: control (CK), 0.01 g/kg LAB plus 2% sugar (S), 0.01 g/kg LAB plus 5% corn flour (C5), and 0.01 g/kg LAB plus 5% corn flour (C10). The results show that all four types of silage had significantly reduced acid detergent fiber, acetic acid content, and ammonia/total nitrogen (p < 0.05). The relative abundance of Lactobacillus spp. was significantly higher (p < 0.05), and that of Weissella, Clostridium sensu stricto 12, and Pantoea genera was significantly lower (p < 0.05) in all four treatments. Group S had significantly increased crude protein content, and groups C5 and C10 had significantly reduced neutral detergent fiber. Overall, group C10 had the highest LA concentration, the highest relative abundance of Lactobacillus spp., and the lowest pH, ammonia/total nitrogen, neutral detergent fiber, and acid detergent fiber. Silage with a complex additive consisting of LAB + 10% corn flour is recommended to achieve good fermentation with high nutritional quality.

Although nitrogen application and cutting frequency (CF) are two important factors affecting forage productivity and quality, their effects on alfalfa (Medicago sativa L.), particularly in humid areas, remain less understood. Here, we investigated the fertilization and cutting regimes for seasonal alfalfa cultivation in humid areas in southern China. Treatments performed over a 2-year period were of a split-plot design with four N application rates (60, 120, 180, and 240 kg N ha⁻¹) and three CFs (five, four, and three times.). After cutting, forage components, yield, and quality were measured. In both 2-year cutting cycles, the effects of N application × CF interactions on forage yield and quality were non-significant. N application and CFs influenced plant height, mass shoot⁻¹, leaf area shoot⁻¹, and shoots plant⁻¹. CF had remarkable effects on forage quality under different N applications, with forage cut five times having the best nutritive value and quality. However, neutral and acid detergent fiber contents were lower than when cutting three times, and produced the lowest yields. Forage cut four times had the highest in vitro digestible dry matter. In conclusion, to obtain high yields and desirable quality, the application of 180 kg N ha⁻¹ and cutting three to four times in spring could be a suitable strategy for alfalfa forage production during seasonal cultivation in humid areas of southern China.

Chemically pretreating lignocellulose has been widely used in the production of clean energy. An energy grass called hybrid Pennisetum was pretreated with different H2SO4 and NaOH concentrations to analyse the effects of an acid and alkali pretreatment on the degradation of hybrid Pennisetum lignocellulose. The chemical composition, hydrolyzed sugar yield, and microstructure were determined. The results showed that a NaOH pretreatment retained more cellulose and removed more lignins, while a H2SO4 pretreatment significantly inhibited the removal of lignins and increased hemicellulose degradation. X-ray diffraction analysis indicated that increasing the concentration of NaOH or H2SO4 could intensify the cellulose polymerization; this effect was stronger with NaOH compared to H2SO4. Scanning electron microscopy images showed that the cellulose bundles pretreated with H2SO4 were arranged tightly, while the cellulose bundles pretreated with NaOH were loose. Fourier transform infrared spectroscopy exhibited that the ether/ester bond between lignins and carbohydrates was broken by the H2SO4 pretreatment. The NaOH pretreatment increased the number of carbonyl and hydroxyl groups, resulting in more hydrophilic lignins, enabling greater facile degradation. Although the two methods are different in terms of destroying the structure of lignocellulose, the NaOH pretreatment can retain more cellulose, which is beneficial to subsequent ethanol production.

Photoperiod-sensitive sweet sorghum (Sorghum bicolor L. Moench) accumulates biomass and sugars during vegetative growth, making it a silage candidate where water limits maize production. This study examined how harvest date and nitrogen (N) rate affect its forage quality and in vitro rumen gas production under rain-fed conditions. In a randomized complete block design with three replications, we evaluated dry matter (DM) yield, morphology, and chemical composition of sweet sorghum harvested at 80 and 110 days after planting (DAP) under five N rates (0, 75, 150, 225, and 300 kg N/ha). Each treatment was ensiled in laboratory-scale bag silos for 90 days. Silage was analyzed for silage quality and 48-h in vitro rumen gas production and fermentation parameters. Delaying harvest from 80 to 110 DAP increased DM yield and fiber fractions (NDF, ADF, lignin), but reduced crude protein (CP), water-soluble carbohydrates (WSC), and in vitro dry matter digestibility (IVDMD) in fresh forage (p < 0.001). Increasing the N rate up to 225 kg N/ha enhanced DM yield, CP, and WSC at both harvest dates. A harvest date × N rate interaction occurred for WSC (p < 0.05). After ensiling, CP and IVDMD were higher in 80-DAP silage. Butyric acid (BA) and ammonia-N (NH₃-N) increased with N rate, but at ≥225 kg N/ha both were lower in 80 DAP silage. The highest 48-h gas production (71.2 and 61.0 mL/200 mg DM) occurred in forage and silage from 110 DAP with 150 kg N/ha. Ruminal pH remained optimal range (6.2–6.8) across treatments. Harvest date and N rate interactively influence sweet sorghum silage quality and rumen fermentability. Under rain-fed conditions, 80 DAP with 225 kg N/ha optimizes silage quality, while 110 DAP with 150 kg N/ha maximizes rumen fermentation potential. These findings support sweet sorghum as a viable silage option where maize production is constrained by water availability.

Oat (Avena sativa L.) silage fermentation often fails due to insufficient lactic acid bacteria (LAB) and low water-soluble carbohydrate content. We investigated the effects of Compound Radix Pulsatillae (CRP; 40 g/kg FM) alone or combined with a commercial LAB inoculant (containing L. plantarum, L. buchneri, and Enterococcus faecium, CRP_LA) on oat silage after 60 days. Compared to control (CK), both CRP and CRP_LA increased dry matter and water-soluble carbohydrate retention while reducing fiber components and ammonia nitrogen (p < 0.05). CRP_LA exhibited superior fermentation quality (lowest pH 4.82, highest lactic acid 47.83 g/kg DM). Using 16S rRNA sequencing and UPLC-MS/MS metabolomics integrated with weighted gene co-expression network analysis (WGCNA), we identified a brown module strongly associated with CRP_LA treatment. Six hub metabolites, belonging to flavonoids, terpenoids, alkaloids, phenolic acids, and nucleotide derivatives, were significantly elevated in CRP_LA silage and showed strong correlations with Lactobacillus abundance and fermentation quality parameters. Correlation-based network analysis revealed that these hub metabolites positively correlated with Lactobacillus abundance, lactic acid, and water-soluble carbohydrate retention, while negatively correlating with spoilage microorganisms (Enterobacter, Acinetobacter, Leuconostoc) and ammonia nitrogen. This multi-omics study provides a metabolite-centric molecular map of the silage microecosystem reshaped by CRP and LAB co-fermentation. The identified hub metabolites—with predicted antimicrobial, antioxidant, and plant-protective functions—represent potential quality markers for functional silage additive development. Mechanistic validation via targeted metabolite supplementation or pathway-specific gene expression analysis is warranted in future studies.