This question is a bit vague. The definition of allegory is, a fable or a short moral story. Another definition could be a story that has a clear secondary meaning. So I am unclear as to whether you mean 'allegory' or not in this question. Another point of confusion is which story you are referring to. I will answer this as best I can assuming you mean the first story that Pi tells the Japanese men who investigate the sinking of the container ship.
In Pi's story, the Zebra represents the injured Chinese shipmate. The hyena represents the cook who steals food from the others on the boat and in the end murders the Chinese shipmate. The orangutan represents Pi's mother and Pi is both himself and the tiger. His relationship with the Tiger is what keeps him alive - in other words, the stories he makes up are what keep him from falling totally into despair.
Hope this helps.