  We generalise the finite range momentum and density dependent
Seyler-Blanchard nucleon-nucleon effective interaction to the case of
interaction between two baryons. This effective interaction is then used to
describe dense hadronic matter relevant to neutron stars in the nonrelativistic
Thomas-Fermi approach. We investigate the behaviour of nuclear symmetry energy
in dense nuclear and hyperon matter relevant to neutron stars. It is found that
the nuclear symmetry energy always increases with density in hyperon matter
unlike the situation in nuclear matter. This rising characteristic of the
symmetry energy in presence of hyperons may have significant implications on
the mass-radius relationship and the cooling properties of neutron stars. We
have also noted that with the appearance of hyperons, the equation of state
calculated in this model remains causal at high density.
