  We study the global polarizations of $\Lambda$, $\Xi^-$, and $\Omega^-$
hyperons in noncentral Au+Au collisions at $\sqrt{s_\mathrm{NN}}=$ 7.7-200 GeV.
We highlight the importance of effect of decay feeddown to the measured global
polarization. With the decay contributions taken into account, the global
polarization ordering $P_{\Omega^-} > P_{\Xi^-} > P_\Lambda$ can be naturally
explained, which is consistent with the observation recently reported from the
STAR experiment from Au+Au collisions at 200 GeV. We also extend our
calculations to predict expectations from the RHIC-BES II data.
