  We show that a torque induced by the local molecular field drives the
zero-temperature ordering dynamics of a conserved Heisenberg magnet to a new
fixed point, characterised by exponents z=2 and $\lambda \approx 5.15$.
Numerical solutions of the Langevin equation indicate that theories using a
Gaussian closure are inconsistent even when the torque is absent. The torque is
relevant even for quenches to T_c, with exponents $z=4-\epsilon/2$ and $\lambda
= d$ (where $\epsilon = 6-d$). Indeed $\lambda$ is always equal to d for
quenches to T_c whenever the order parameter is conserved.
