NOVELTY - Method for managing protein content of multiple distiller's grain co-products of a fermentation process, involves separating whole stillage or spent grains into wet cake and thin stillage, removing protein rich distiller's grain co-product and producing reduced protein thin stillage, removing at least some non-protein components from reduced protein thin stillage, and adding all or portion of the reduced protein thin stillage, having at least some non-protein components removed, to at least some of the wet cake.    USE - The method is useful for managing protein content of multiple distiller's grain co-products of a fermentation process (claimed).    DETAILED DESCRIPTION - Method for managing protein content of multiple distiller's grain co-products of a fermentation process, involves (a) separating whole stillage or spent grains into wet cake and thin stillage, removing protein rich distiller's grain co-product having greater than 40 wt.% protein on a dry matter basis from thin stillage and producing reduced protein thin stillage, removing at least some non-protein components from reduced protein thin stillage, and adding all or portion of the reduced protein thin stillage, having at least some non-protein components removed, to at least some of the wet cake, (b) separating whole stillage or spent grains into wet cake and thin stillage, removing a protein rich distiller's grain co-product having greater than 40 wt.% protein on a dry matter basis from the thin stillage and producing a reduced protein thin stillage, and removing at least some non-protein components from the wet cake and producing a protein enriched wet cake, or (c) separating whole stillage or spent grains into wet cake and thin stillage, removing a protein rich distiller's grain co-product having greater than 40 wt.% protein on a dry matter basis from the thin stillage and producing a reduced protein thin stillage, adding microorganism to reduced protein thin stillage and growing biomass having higher protein content on a dry weight basis than wet cake, consuming at least some of the non-protein components of the reduced protein thin stillage during the course of growing the biomass, and harvesting the biomass. An INDEPENDENT CLAIM is included for system for managing the protein content of multiple distiller's grain co-products in a grain fermentation facility by separating whole stillage or spent grains into wet cake and thin stillage, removing a protein rich distiller's grain co-product having greater than 40 wt.% protein on a dry matter basis from the thin stillage and producing a reduced protein thin stillage, removing non-protein components of the reduced protein thin stillage, wet cake, and both the reduced protein thin stillage and the wet cake, and achieving a desired protein content in multiple distiller's grain co-products by combining, proportionately and as needed, protein containing streams chosen from thin stillage, wet cake, reduced protein thin stillage, reduced protein thin stillage having non-protein components removed, additional protein removed from reduced protein thin stillage, wet cake having non-protein components removed, protein rich distiller's grain co-product, biomass grown on reduced protein thin stillage, evaporated concentrates of liquid streams and dried forms of wet solids.