Improving feed safety and nutritional utilization of cassava waste through solid-state fermentation for sustainable...

Cassava processing generates substantial by-products that have potential as alternative duck feed ingredients; however, their utilization is limited by high cyanide content and low nutrient availability. This study evaluated the effectiveness of solid-state fermentation (SSF) in improving feed safety and nutritional utilization of cassava waste for ducks. A completely randomized design with a 3 × 3 factorial arrangement was applied, consisting of three inoculum dosages (2%, 4%, and 6%) and three fermentation durations (3, 6, and 9 days). Solid-state fermentation significantly enhanced cellulase and β-glucosidase activities, resulting in improved substrate degradation and detoxification. The highest enzyme activities were observed at a 4% inoculum dosage and 9 days of fermentation. Under these conditions, crude protein content increased from 20.82% to 24.44%, crude fiber content decreased, and hydrogen cyanide (HCN) concentration was markedly reduced to 72.76 ppm. Biological evaluation using a digestibility and metabolic trial in ducks demonstrated that fermented cassava waste significantly improved nitrogen retention, metabolizable energy, and crude fiber digestibility compared with less optimized treatments. These results indicate that residual cyanide levels did not impair nutrient utilization or metabolic efficiency in ducks. In conclusion, solid-state fermentation represents an effective biotechnological approach to enhance feed safety and nutritional utilization of cassava waste, supporting its use as a sustainable alternative feed ingredient for ducks production in tropical regions.