They would probably lose a lot more if they allowed the zoo to stay open and someone slipped and injured themselves and then claimed against the zoo. Remember the complaints when the zoo was evacuated because of the chimp escape?
Blackpool has been closed for most of the week as well if their Twitter updates are correct.
With the number of visitors they turned away on the dat they would have lost money any way so better to close for the day and not risk losing more by getting sued by somebody having slipped on ice,just so people know the zoo spent over 2 hours putting grit down to make the zoo safe but it was so cold it didn`t even melt the ice,so to me they made the best decision that they could for the safety of the visitors by closing for the day.