effect of the AGN feedback on such distributions. Since the distinctive feature of our AGN feedback model (associating the feedback to the brigh QSO phase) is constituted by an effect peaking at redshift $1.5<z<3.5$, we particulary focus on the properties of high-redshift galaxies, and we compare with the observed number density of EROs up to $z=2.5$, and of Distant red Galaxies (DRGs), selcted by observed-frame $J-K>2.3$ (Franx et al. 2003; Van Dokkum et al. 2003), up to $z\approx 4$. In the final section we discuss our results.

THE MODEL
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We adopt the semi-analytic model (SAM) of galaxy formation described in Menci et al. (2005); this connects the baryonic processes (gas cooling, star formation, Supernovae feedback) to the merging histories of the DM haloes (with mass $M$, virial radius $R$ and circular velocity $V$) and of the galactic sub-haloes (with mass $m$, radius $r$ and circular velocity $v$) following the canonical recipes adopted by SAMs of galaxy formation (Kauffman, White & Guiderdoni 1993; Cole et al. 2000; Somerville, & Primack 1999; Somerville, Primack & Faber 2001; Menci et al. 2002; 2004a; Okamoto & Nagashima 2003).

The host DM haloes contain hot gas (with mass $m_h$) at the virial temperature $T$. 