A rotary cutting mechanism (25) has a disc cutterbar (26) with transversely spaced rotatable disc cutters (28) to sever standing crop material by an impact action. A rotatable conditioning mechanism (30) may be mounted rearwardly of the cutterbar (26) to receive and condition severed crop material. Each disc cutter (28) is provided with a crop lifter (50) affixed to the peripheral portion (44) thereof and adjacent each knife (45) in leading relationship thereto. The crop lifter (50) has an inclined ramp (55) operable to lift previously severed crop material away from the corresponding knife (45) before the knife (45) operatively severs further standing crop material. The crop lifter (50) is also operable to facilitate a feeding of the severed crop material into the conditioning mechanism (30). The top (56) of the crop lifter (50) is being positioned in substantially the same plane as the raised central portion (41) of the disc cutter (28) for properly lifting the severed crop material toward the conditioning mechanism (30) and for protecting the hardware (47) detachably fastening the corresponding knife (45) to the disc cutter (28).