You don't need that many boars tbh. And later if you get 1 and 2 star boars they drop a lot more meat when slaughtered as well.
I have a pen of like 5-7 2 star and never had to little meat.
You also do not have to feed them constantly, but they wont breed unless happy.
There is also a limit of how many you can have in an area before they stop breeding.