Biochar-Driven Microbial Shifts Enhance Feed Digestibility and Mitigate Methane Emissions in Hybrid Pennisetum Silage

Abstract

To mitigate environmental pollution caused by the large-scale accumulation of livestock manure and to investigate synergistic pathways for efficient agricultural waste utilisation, improved silage quality, and enhanced feed use, this study used hybrid Pennisetum as the raw material. The experiment included four treatment groups: a control group without additives (CK, 10 mL of sterile water), cellulase group (CE, 5 g/kg fresh material), propionate group (PA, 5 mL/kg fresh material), and cow dung biochar group (BC, 40 g/kg dry matter). Samples were collected at 14, 28, and 56 days after silage preparation to measure various indicators. The results showed that BC treatment not only improved fermentation quality but also increased in vitro dry matter digestibility (IVDMD) by 2.71% and reduced methane production by 20%. Membership function analysis revealed that CE treatment exhibited the highest silage quality (membership value, 0.7238). Microbial community analysis indicated that all treatments significantly increased the abundance of Firmicutes and decreased the abundance of Proteobacteria (p < 0.05). Notably, Lactobacillus was significantly increased in the PA group and Pediococcus in the BC group (p < 0.05). Functional prediction based on PICRUSt2 showed that PA improved the silage quality of hybrid Pennisetum by upregulating carbohydrate and energy metabolism pathways. In conclusion, this study demonstrated that biochar prepared from cow dung had a positive effect on the silage of hybrid Pennisetum, offering a new approach for the resource utilisation of livestock waste in animal husbandry.