A packaging bag for a liquid biological substance such as animal semen,
including two walls made of plastic material joined in such a manner as
to delimit a pouch for receiving the substance and, communicating with
the pouch, an evacuation conduit whose end part, in the absence of
opening of the bag, is closed by the joined walls, wherein, force-fitted
in the conduit, a cannula being able to communicate with the pouch is
provided, while a second end of the cannula is situated in the proximity
of the end part of the conduit having a conical or substantially conical
constriction, and wherein conduit communicates, over a part of its
length, with at least one zone situated not far from the end part, in
which the two walls are not joined.