Peanut butter mixed with bacon grease and smeared on the bars: However, a much more effective method is to place a live chicken in one trap, with another placed back to back with it. I wouldn't subject a chook to that sort of stress, but that's just me. Depends on one's chops for losses free...
Yes, urine/pheromones are most useful when trapping within the same species, during certain times of the year under certain conditions. Insofar as counting on ANY olfactory signal to dissuade a hungry pred? Maybe, initially, if the wind is right and the temp/humidity level is adequate...