I seldom go to KFC. Not a fan of their food, but I do not believe that they purchase chicken that is bulked via steroids (in the UK).
Years ago, farmers started using antibiotics such as tylosin, sub-therapeutically, the rationale was that it would allow the livestock to digest foodstuff more efficiently. The EU banned the use of sub-therapeutic antibiotics years ago. The USA still allows it. The FDA want to ban it but Congress will not pass the requisite legislation.
I am not a fan of McDonald's but the US beef that they purchase (for the American market) is free of the likes of tylosin and steroids (the EU meat is not allowed to contain either). In no way an apologist for either of the questionable companies, but it doesn't help to see them being unfairly maligned. Go ahead and criticise them, I don't like either Mega Global Inc., but please try to be accurate. If you have verifiable evidence of KFC selling steroid based chicken in the UK, seriously, I want you to post it.