Commonly, in dream dictionaries, the chicken is said to represent fertility (the whole "chicken and egg" argument notwithstanding).
In Chinese dream interpretation, the chicken is symbolic of pride: he is the first creature to greet the sun, the first to announce his presence to the world (which, in light of the age-old argument, may be the East's solution to the question: the chicken announced itself, and then bothered to procreate).
However, they also have a secondary symbolism.
Chickens are agents of enlightenments in their adulation of dawn.
Throughout mythology and folklore, it is always the chicken who represents the break of day; they are the auditory signal that wakes the sleepers.