wtf??

who throws mince over the fence?

or gives off food to animals??

I'd be worried ... sounds awfully suss to me ...

do you have any neighbours who you think might have done it (with good or bad intentions)? can you ask them?
Mine used to. he'd throw bones n stuff over to my dog (and bopped him on the head with a rabbits head) and the two dogs on the other side of the paddoc too.
maybe they thought they where helping out by not wasteing the food? and FIW - i give my used by meat fairly often...he'll eat it over the tinned food

hope the smell clears soon.