Trial and error teaches you that the best protection is a fence, equipped, if possible, with electric wiring that gives a memorable but otherwise harmless shock. If a fence is not possible for you, sprays such as Deer Away and Get Away and other commercial or homemade deterrents will work to some extent, but must be constantly renewed as rain and time decreases their efficiency. Empty soda bottles, buried with the tops exposed, whistle eerily in the wind and may scare away rabbits. Nurseries peddle natural scent repellents like coyote or fox urine. You could try your zoo for wolf urine.
Some plants protect other plants.
For example, beans and pumpkins planted between rows of corn are said to discourage raccoons from raiding your prized ears because they don't like the feel of the vines and foliage. This can mean an expense of thousands of dollars, depending on the size of the enclosure and the quality of the fencing. Electrifying the fence is permitted by some communities and forbidden by others. I put up the plastic fencing because the chicken wire I had used would rust out every three years or so. So I placed a second wire along the base of the fence.