Dispersible additive systems for polymeric materials include dispersant-coated pigments in a liquid nonaqueous polymeric carrier. The additive systems are most preferably in the form of a particulate nonaqueous paste which can be added in metered amounts (dosed) to a melt flow of the polymeric host material prior to being shaped (for example, prior to being spun into synthetic filaments). By providing a number of additive systems having a number of different additive attributes, and controllably dosing one or more into the melt flow of polymeric material, shaped objects of the polymeric material (e.g., melt-spun filaments) having different additive attributes may be produced on a continuous basis without shutting down the shaping operation.