The main point here is that why need to use them for Betting and fun when chicken are provided for meal ? I mean instead of using them to make us enjoy in gambling there are so much to choose from that does not involve any lives, this may sounds corny but I think like Dog fight and other form of animal fighting ? these animals needs to be treated fair , kill them to fed us and that is OK but using them for fun is far different to what needs to be.
How can you make the distinction? You may having the opinion that killing these animals for food is OK. But someone else maybe against that idea. How you are going to react if someone tells you that you should become vegetarian, because you are not allowed to kill animals for food? Let's respect everyone's individual freedom. If you are allowed to kill animals for food, others are also allowed to kill animals for the purpose of entertainment. The most important thing here is to refrain from imposing a false sense of morality over others.
Actually what you said right now is task of every other person to make it's conclusion and personal decision on what you can do with youyown animal, depending on what you have in mind, because from my understanding i believe that some people have theie own method or kind of involving also engaging yourself into something else. So i think that anyone that have something knows it's functions ans it depends on the individual.