  We derive constraint on the effective number of neutrino species N_nu from
the cosmic microwave background power spectrum of the WMAP and galaxy
clustering power spectrum of the SDSS luminous red galaxies (LRGs). Using these
two latest data sets of CMB and galaxy clustering alone, we obtain the limit
0.9 < N_nu < 8.2 (95% C.L.) for the power-law LambdaCDM flat universe, with no
external prior. The lower limit corresponds to the lower bound on the reheating
temperature of the universe T_R > 2 MeV.
