I was also apprehensive of leaving the cats behind, but then I can't take them with myself either. I'll be travelling from one place to another and, currently, have no permanent home. So, may be, I will give them to someone who would take good care of them.

And, Yeah! You're absolutely right that the healthy wild environment the cats need no longer exists. But, the castration still doesn't sound good to me. It definitely helps to pacify the cats and bring them under control, but wouldn't that make their existence useless?

Because, after all, felines were made to feel their hunger, suffer, wander and discover their destiny through that process. That's how they are supposed to come into contact with the intelligence their wild side has to offer.

However, I would also like to say that it's my personal opinion and I've not much knowledge about the subject.