We consider the space

of all real functions that are
integrable with respect to a measure

with values in a real
Fréchet space
X. We study L-weak compactness in this space. We
consider the problem of the relationship between the existence of copies of

in the space of all linear continuous operators from a
complete DF-space
Y to a Fréchet lattice
E with the Lebesgue
property and the coincidence of this space with some ideal of compact
operators. We give sufficient conditions on the measure

and the space
X that imply that

has the Dunford-Pettis property.
Applications of these results to Fréchet AL-spaces and Köthe
sequence spaces are also given.