NOVELTY - Integrating processes to an existing plant, comprise: identifying the existing plant that converts grain to ethanol; separating bran from other components in the feedstock; breaking down cellulose and hemicellulose using water and heat; hydrolyzing the bran with a cellulase enzyme complex cocktail and fermenting with an organism a hydrolysis and cellulosic fermentation processes; and combining the cellulosic beer with starch to increase overall yield per feedstock unit in the existing plant.    USE - The integrating processes are useful for treating a cellulosic feedstock to produce a fermented product, a cellulosic biofuel (preferably ethanol) (all claimed), and a high-value protein animal feed.    ADVANTAGE - The integrating processes ensure economical production of cellulosic biofuel with high yield using existing piping, storage, and loading infrastructure at the existing facilities.    DETAILED DESCRIPTION - Integrating processes to an existing plant, comprise: identifying the existing plant that converts grain to ethanol, where the existing plant performs a milling process, a cook process, a fermentation process, a distillation process, a dehydration process, an evaporation process, a solid-liquid separation process and a propagation process; separating bran from other components in the feedstock by a fractionation process; breaking down cellulose and hemicellulose in the bran using water and heat by a pretreatment process; hydrolyzing the bran with a cellulase enzyme complex cocktail and fermenting with an organism to produce cellulosic beer by hydrolysis and cellulosic fermentation processes; and combining the cellulosic beer with starch from the grain in the existing plant to increase overall yield per feedstock unit in the existing plant. An INDEPENDENT CLAIM is included for a process-I for treating a cellulosic feedstock, comprising: either fractionating the cellulosic feedstock by separating components of the cellulosic feedstock into a large-particle stream from a small-particle stream, pretreating the large-particle stream by adding water to the large-particle stream in a tank to create a low-solids slurry, where a percentage of solids in the low-solids slurry comprises less than 25%, injecting steam directly to the low-solids slurry to raise a temperature of the low-solids slurry, adding a chemical to the heated low-solids slurry to cause a reaction zone to occur, and hydrolyzing and fermenting the low-solids slurry to produce cellulosic beer; or breaking down cellulose and hemicellulose using heat and an acid and neutralizing using a base, and hydrolyzing pretreated feedstock by adding an enzyme to convert cellulose and hemicellulose to sugars and fermenting the pretreated feedstock with the organism to produce a fermented product.