The present invention relates to a process for preparing an oilseed meal, preferably rapeseed meal with enriched content of proteins by sieving onto a classifying element with rectangular or elliptical holes, preferably rectangular holes and wherein the classifying element is oscillating, or vibrating. It further relates to the use of a frame comprising a classifying element for enriching the protein content in oilseed meal with at least 3% in comparison with original oilseed meal. It relates to poultry, pig feed or aqua feed containing the oilseed meal with enriched content of proteins.
