I prefer to use a hard plastic, screw lid, container with holes punched in lid. I then soak paper towels in oil from tuna, or liquid from canned salmon. This allows the odor to waft to the coon/whatever but, once in the trap, they can't make a mess and, they get nothing to eat.
During the dog days of summer (heat decomposes the `scent packs' to quickly), I just use dry cat food. If the chooks and turks are locked down at night the vermin will, 99% of the time, go for the easy pickings and end up at my Turkey Vulture feeding station.
Good luck!
Addendum for the curious: If they are locked down at night, why trap? one might ask: Well, at this location we've had several, daytime raccoon forays (healthy and fat) a couple of opossum attempts after dawn, and many fox (the Reds are imported, invasive, ornamentals - like Snakeheads and Multifloral Rose and should be dispatched, regardless). In order to free range for a couple of hours knocking down the opposition is a given and I don't like to waste time scanning the tree line any more often than I have to.