  We study $D$ - meson production at forward rapidities taking into account the
non - linear effects in the QCD dynamics and the intrinsic charm component of
the proton wave function. The total cross section, the rapidity distributions
and the Feynman - $x$ distributions are calculated for $p p$ collisions at
different center of mass energies. Our results show that, at the LHC, the
intrinsic charm component changes the $D$ rapidity distributions in a region
which is beyond the coverage of the LHCb detectors. At higher energies the IC
component dominates the $y$ and $x_F$ distributions exactly in the range where
the produced $D$ mesons decay and contribute the most to the prompt atmospheric
neutrino flux measured by the ICECUBE Collaboration. We compute the $x_F$ -
distributions and demonstrate that they are enhanced at LHC energies by
approximately one order of magnitude in the $0.2 \le x_F \le 0.8$ range.
