You would first need a save with everything unlocked (google) the you would need "KG's Resigner" (google) it's free. Once you resign the save it should work on your PS3. Or, you could buy a game genie, there is a code to unlock all animals.
Ok you may need to make an account (it's free) to view the post in the link below. It has a save with ALL animals unlocked, 44 of EVERY item in the game, and maxed out (999) stats. You will still need to resign the save as mentioned above. There are some great guides on the same site on how to resign game saves. Hope this helps you!!!