An annular rotary knife blade (500;1500) for a power operated rotary knife (100;1100), the annular rotary knife blade (500;1500) configured to be supported for rotation about a central axis of rotation in a direction of rotation by an annular blade housing (600;1600) of the power operated rotary knife (100;1100), the annular rotary knife blade (500;1500) comprising: an annular body (510;1510) including an inner wall (502;1502) and an outer wall (504;1504) and an upper end (506;1506) and a lower end (508;1508), the annular body (510;1510) of the rotary knife blade (500;1500) including a bearing surface (542;1542) for rotational support of the rotary knife blade (500;1500) and a driven gear (520;1520) for rotationally driving the rotary knife blade (500;1500), the rotary knife blade (500;1500) further including a blade section (550;1550) extending from the lower end (508;1508) of the annular body (510;1510), the blade section (550;1550) including a blade frustoconical wall (556;1556) extending between an upper end (552;1552) of the blade section (550;1550) and a lower end (554;1554) of the blade section (550;1550), the lower end (554;1554) of the blade section (550;1550) spaced radially inwardly from and axially below the upper end (552;1552), a plurality of circumferentially spaced apart notches (560;1560) extending from the lower end (554;1554) of the blade section (550;1550) into the blade frustoconical wall (556;1556), each of the plurality of notches (560;1560) including a peripheral wall (562;1562) surrounding a central open portion (564;1564), characterized in that the peripheral wall (562;1562) includes a leading portion (566;1566), a central portion (568;1568), and a hook-shaped trailing portion (570;1570) with respect to the direction of rotation of the annular rotary knife blade (500;1500), the leading portion (566;1566) and the hook-shaped trailing portion (570;1570) being circumferentially spaced apart by the central portion (568;1568), the hook-shaped trailing portion (570;1570) including a cutting portion (580;1580), the cutting portion (580;1580) of each of the plurality of circumferentially spaced apart notches (560;1560) defining a cutting edge (590;1590) of the rotary knife blade (500;1500). an annular body (510;1510) including an inner wall (502;1502) and an outer wall (504;1504) and an upper end (506;1506) and a lower end (508;1508), the annular body (510;1510) of the rotary knife blade (500;1500) including a bearing surface (542;1542) for rotational support of the rotary knife blade (500;1500) and a driven gear (520;1520) for rotationally driving the rotary knife blade (500;1500), the rotary knife blade (500;1500) further including a blade section (550;1550) extending from the lower end (508;1508) of the annular body (510;1510), the blade section (550;1550) including a blade frustoconical wall (556;1556) extending between an upper end (552;1552) of the blade section (550;1550) and a lower end (554;1554) of the blade section (550;1550), the lower end (554;1554) of the blade section (550;1550) spaced radially inwardly from and axially below the upper end (552;1552), a plurality of circumferentially spaced apart notches (560;1560) extending from the lower end (554;1554) of the blade section (550;1550) into the blade frustoconical wall (556;1556), each of the plurality of notches (560;1560) including a peripheral wall (562;1562) surrounding a central open portion (564;1564), characterized in that the peripheral wall (562;1562) includes a leading portion (566;1566), a central portion (568;1568), and a hook-shaped trailing portion (570;1570) with respect to the direction of rotation of the annular rotary knife blade (500;1500), the leading portion (566;1566) and the hook-shaped trailing portion (570;1570) being circumferentially spaced apart by the central portion (568;1568), the hook-shaped trailing portion (570;1570) including a cutting portion (580;1580), the cutting portion (580;1580) of each of the plurality of circumferentially spaced apart notches (560;1560) defining a cutting edge (590;1590) of the rotary knife blade (500;1500).