This study aimed to screen high-yield and high-quality sorghum–sudangrass hybrid varieties suitable for popularization and cultivation in the Hulunbuir region through a comprehensive evaluation of silage fermentation quality and bacterial community. Comparative analyses were conducted on six sorghum–sudangrass varieties, namely, sorghum–sudangrass hybrid 3 (SS1), sorghum–sudangrass hybrid 4 (SS2), sorghum–sudangrass hybrid 5 (SS3), sorghum–sudangrass hybrid 7 (SS4), sorghum–sudangrass hybrid 8 (SS5), and Super Sugar–Dwarf Sorghum (SS6). The harvested sorghum–sudangrass at the late milk stage was chopped, vacuum-sealed in polyethylene bags (30 cm × 40 cm), and subjected to 60 days of ensiling fermentation. The results revealed significant differences among different varieties (p < 0.05). SS2 achieved the highest fresh herbage yield of 78.26 t/hm2, while the fresh yield of SS4 was 57.39 t/hm2, approximately 26.7% lower than that of SS2. However, SS4 exhibited superior quality, with the thickest stem diameter of 20.26 mm (p < 0.05). It exhibited the highest crude protein content, reaching 5.72% DM; its silage pH was relatively low, at only 3.71 (p < 0.05); its fiber content was significantly reduced (acid detergent fiber, ADF = 40.03% DM, p < 0.05); and it was rich in Lactococcus and Lactobacillus (p < 0.05). The ensiling process of SS4 highly significantly decreased bacterial diversity (p < 0.01) and shifted the dominant bacterial phylum from Proteobacteria to Firmicutes. Functional prediction indicated that the bacterial community of SS2 possessed the highest predicted abundance of functional genes related to cellulase and beta-glucosidase (p < 0.05). Our findings suggest that SS2 should be prioritized for production systems aiming for maximum biomass accumulation, whereas SS4 is recommended as a superior variety for high-quality animal nutrition systems where fermentation stability and nutrient preservation are paramount.
Song et al. (Mon,) studied this question.