  We study some effects the inclusion of the radiation energy component in the
universe, Omega_r, can have on several quantities of interest for the
large-scale structure of the universe in a LCDM cosmological simulation;
started at a very high redshift (z=500). In particular we compute the power
spectrum density, the halo mass function, and the concentration-mass relation
for haloes. We find that Omega_r has an important contribution in the long-term
nonlinear evolution of structures in the universe. For instance, a lower matter
density power, by approx 50%, in all scales is obtained when compared with a
simulation without the radiation term. Also, haloes formed with the Omega_r
taken into account are approx 20% less concentrated than when not included in
the Hubble function.
