Since the egg cell is a gamete (and gametes are produced through meiosis), they number of chromosomes in the egg cell would be half that of any other cell of the animal's body, in this case 27.
This is so that when the animal mates and its egg is fertilised by a sperm cell (which will also contain 27 chromosomes), the zygote formed will have 27 chromosomes from each parents, giving it 54 chromosomes, the normal number for an animal of this particular species.