  We have applied the Meson Cloud Model to calculate inclusive momentum spectra
of pions and kaons produced in high energy proton-proton and proton-nucleus
collisions. For the first time these data are used to constrain the cloud
cut-off parameters. We show that it is possible to obtain a reasonable
description of data, especially the large $x_F$ ($x_F \geq 0.2$) part of the
spectrum and at the same time describe (partially) the E866 data on $\bar d -
\bar u$ and $\bar d / \bar u$. We also discuss the relative strength of the
$\pi N$ and $\pi \Delta$ vertices. We find out that the corresponding cut-off
parameters should be both soft and should not differ by more than 200 MeV from
each other. An additional source (other than the meson cloud) of sea antiquark
asymmetry, seems to be necessary to completely explain the data. A first
extension of the MCM to proton nucleus collisions is discussed.
