I re-read the AZA accreditation standards after I realized that I may have misinterpreted some parts of them the first time. One thing that was interesting is the AZA standards for visitor interactions with various animals. It's apparently allowable for visitors to interact with reptiles, primates and hoofstock if the specimens are extensively tested for disease. Since primates need to be tested for a lot of things and salmonella cannot be eradicated in reptile populations (forcing zoos to enforce hand-washing), I understand why zoos would be disinclined to bother with the precautions they need to allow visitor interactions. However AZA zoos allow giraffe feeding and sometimes domesticated hoofstock in petting zoos, and concerns seem to be similar for a domestic pig vs a peccary or a domestic goat vs a duiker. I've also noticed that non-AZA zoos with hoofstock usually seem to let their visitors feed them (and in a few cases even pet them). So I guess what I'm wondering is A. why AZA zoos seem not to allow feeding of animals other than giraffes, and B. why I've never small hoofstock in walk-in exhibits at AZA zoos? With large hoofstock I get that there's a concern for visitors literally getting their toes stepped on, it occurred to me that if I were to design a large aviary I'd want to include some animals other than birds (despite my love of birds) if the wouldn't cause problems for other occupants (like I imagine peccaries would eat eggs of ground-nesting birds). So duikers in an Africa aviary or chevrotains in an Asia aviary seem like good candidates for that. And I'm wondering if there's a reason I haven't seen a zoo do it?