Suitability of anaerobic fungi culture supernatant or mixed ruminal fluid as novel silage additives.

This study investigated silage quality characteristics and ruminal fiber degradability of grass and straw ensiled with either anaerobic fungi (AF) supernatant with active fungal enzymes or mixed ruminal fluid as novel silage additives. Compared to control silages, AF supernatant improved the quality of grass and straw silages as evidenced by decreased pH, acetic acid concentration, and dry matter losses. Likewise, mixed ruminal fluid enhanced lactic acid fermentation, which further resulted in lower pH of the treated grass silage. The ruminal fiber degradability was determined using in situ incubations and, compared to controls, the cellulose degradability was higher for grass silage with AF supernatant, whereas ruminal degradability of straw silage was reduced by this treatment. In contrast, mixed ruminal fluid did not influence fiber degradability of silages in the rumen. Concluding, both novel additives improved silage quality, whereas only AF supernatant enhanced ruminal fiber degradability of grass silage and therefore may represent an approach for improving forage utilization by ruminants. KEY POINTS: • Enzymes of anaerobic fungi supernatant improve quality of grass and straw silages. • Mixed ruminal fluid enhances lactic acid fermentation when ensiling grass and straw. • Enzymes of anaerobic fungi supernatant increase ruminal grass silage degradability.