Not really an AIBU but need a quick answer as we are going this afternoon!
Theres no danger is there? Done a quick google search, nothing comes up. I know its unsafe for pregnant women as we went last year and they had signs up (although I was actually 2 weeks pregnant then and didnt know it yet!)
DP was a bit concerned but I dont think theres any danger. DS is not actually going to be touching the animals and neither am I!