  With Monte Carlo simulations, we investigate short-time critical dynamics of
the three-dimensional anti-ferromagnetic Ising model with a globally conserved
magnetization $m_s$ (not the order parameter). From the power law behavior of
the staggered magnetization (the order parameter), its second moment and the
auto-correlation, we determine all static and dynamic critical exponents as
well as the critical temperature. The universality class of $m_s=0$ is the same
as that without a conserved quantity, but the universality class of non-zero
$m_s$ is different.
