  We calculate neutrino cross sections from neutral current reactions in dense
matter containing hyperons. We show that Sigma- hyperons give significant
contributions. To lowest order, the contributions from the neutral Lambda and
Sigma0, which have zero hyper-charge, vanish. However, their presence furnishes
baryon number which decreases the relative concentrations of nucleons. This
leads to significant reductions in the cross sections. Due to the uncertainty
in strong interactions at high density, the neutrino opacity may vary by a
factor of about 2 depending on the behavior of the effective masses.
