A mechanical discharger (a) combined with an extractor device (b) of the bulk product (c) stored in a silo bag (d), of the type comprising a winding tube (10) driven by rotation and which is mounted on support arms (11) hinged to a wheeled (2) frame (1) and wherein the product extractor device (b) is a continuous conveyor structure having a lower loading part (5) substantially horizontally and transversely positioned within the bag-silo (d). From the discharge end, the silo-bag wall (d) is cut with two lateral longitudinal cuts, being the wall divided into an upper part (d1) and a lower one (d2). The winding tube (10), draws by rotation and by the corresponding end the upper half portion (d1) of the silo bag (d). A second winding tube (20) is mounted underlying and parallel to the first tube (10) through support and positioning means (30) and though a mechanical transmission (40). The second winding tube (20) draws by rotation and by the same end, the lower half part (d2) of the silo bag (d). It is thus achieved that the extractor device (b) only draw the product (c) in good condition, while the lower layer of the spoiled product (cl), is drawn by the lower part (d2) of the bag wall and then discarded through the open end of the bag.