@David Matos Mendes European/Belgian zoos are not allowed to feed live vertebrates normally, only insects or other invertebrates are normally allowed to be fed live. The chicken would already have been dead when it was fed whole. But the feeding of whole prey items or large carcass pieces is not that uncommon in European zoos.
@KevinB
I'm happy it's not the case. I'm particularly against the offering of living animals as prey. Killing the animals before offering them as food is much more humane IMO, as certain species would spend a considerable time playing/shreding the animal before actually killing.