  By the single crystal inelastic neutron scattering the orthoferrite HoFeO3
was studied. We show that the spin dynamics of the Fe subsystem does not change
through the spin-reorientation transitions. The observed spectrum of magnetic
excitations was analyzed in the frames of linear spin-wave theory. Within this
approach the antiferromagnetic exchange interactions of nearest neighbors and
next nearest neighbors were obtained for Fe subsystem. Parameters of
Dzyaloshinskii-Moriya interactions at Fe subsystem were refined. The
temperature dependence of the gap in Fe spin-wave spectrum indicates the
temperature evolution of the anisotropy parameters. The estimations for the
values of Fe-Ho and Ho-Ho exchange interaction were made as well.
