We discuss production of $D^0$ and ${\bar D}^0$ mesons in
proton-nucleus collisions in fixed target experiments.
We include gluon-gluon fusion, intrinsic charm and perturbative
recombination.
We compare rapidity and transverse momentum distributions
obtained within our approach with recent fixed target LHCb
experimental data.
All the mechanisms seem important for inclusive
production of $D^0 + {\bar D}^0$ mesons. The recombination mechanism
seems crucial to understand asymmetry in production of $D^0$ and
${\bar D}^0$ mesons.