Friedman: better using a control set??

When performing a Friedman analysis on the frequency of a certain behaviour
in a given species in different conditions [for istance "pre-feeding time"
(30 min before food is available), "feeding time" (30 min from food
provisioning), "post-feeding time"(30 min beginning the end of the feeding
time)], is it better to use also a control condition (i.e. a period where
food is not involved) or the test is sufficient to single out differencies
in thet behaviout in the "around food" context?!?!
THANKS

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Tom