Abstract: A process is disclosed for manufacturing a xylanase-rich enzyme complex by cultivating a xylanase-producing microorganism of the genus Trichoderma in a nutrient medium involves cultivating said microorganism in a nutrient medium containing a pre-treated thin stillage of rye as both the xylanase inductor and the carbon source. Pre-treatment of the thin stillage comprises removing the solid constituents of the thin stillage of rye, concentrating the non-volatile components by evaporation of water and other volatile substances, and autoclaving the thin stillage of rye concentrate resulting therefrom. De-oiled soya meal or soya meal liquor can be used as an additional xylanase inductor and as a nitrogen source. Addition of the de-oiled soya meal or soya meal liquor to the pre-treated thin stillage of rye further increases the xylanase production. The enzyme complexes so manufactured can be used immediately in the animal feedstuff industry such as poultry feeds.