Feeding value improvement by co-fermentation of corn-ethanol co-product and agro-industrial residues with Rhizopus oryzae

Corn dried distiller's grain with solubles (cDDGS) is a feeding ingredient for monogastric animals but with limited inclusion rate due to its imbalanced amino acids, high fiber content, and anti-nutritional compounds. Moreover, production of cDDGS is costly and energy intensive. This study investigated fungal fermentation of corn stillage mixing with other dry agro-industrial residues which could by-pass the energy-intensive drying process while improving nutritional value of the mixed substrates. Rhizopus oryzae was used to ferment WDGS blended with canola meal (CM), cottonseed meal (CSM), sugar beet pulp (SP) and soybean hull (SH) at different ratio at 28 ℃ for 12 days. Results suggested that short incubation period (4 days) was favorable for improvement of protein and key amino acids profile. Substrate mixture with C/N ratio above 3 effectively reduced ammonia generation. Significant reduction (p < 0.05) of structural carbohydrates (mainly glucan with degradation by 20–30 %) occurred after fermenting WDGS mixing with CM and SP. Substrate with all mixing ratio of SP or SH, and lower ratio (less than 50 %) of CM or CSM showed phytate degradation by 30–75 %. This study proved the feasibility of solid-state fermentation in improving feeding value of WDGS and agro-residues for monogastric animals.