Effects of Adding Astragali Radix and Inulae Radix on Fermentation Quality, Nutrient Preservation, and Microbial...

Chinese herbal medicine (CHM) residues represent a promising and sustainable category of silage additives, with the potential to modulate fermentation and enhance nutrient preservation. This study investigated the effects of two CHMs, Astragalus membranaceus L. (Astragali Radix, AR) and Inula helenium L. (Inulae Radix, IR), on the fermentation profile, nutritional composition, and bacterial community structure in barley silage. The forage was ensiled without additive (control, CK), or with 1% or 2% (w/w) of AR or IR for 75 days. The results showed that all additive treatments significantly improved fermentation quality, as evidenced by lower pH and reduced ammonia-nitrogen (NH₃-N) content compared to CK. The 2% IR treatment was most effective in promoting homolactic fermentation, yielding the highest lactic acid content and lactic acid-to-acetic acid ratio. Nutritionally, additives significantly increased dry matter, starch, and water-soluble carbohydrates, while decreasing neutral and acid detergent fiber contents. High-throughput sequencing of the 16S rRNA gene revealed that both herbal additives profoundly reshaped the microbial community. They suppressed undesirable bacteria and significantly enriched beneficial Lactobacillus species. Principal component analysis confirmed a distinct separation in microbial community structure between control and treated silages. These findings underscore the potential of these herbal residues as natural modulators of the silage microbiome for improved forage conservation.