Why has your cow got a bloated stomach?

I think you've been feed it way too much grain than what it needs. You probably were told by someone that cows need grain, and didn't listen to the other part of the equation that cows need to have hay and grass to eat. Also, it's likely that you haven't provided enough exercise for your pet cow: they need space to move around too, and can't just be kept in a stall all its life.