Why are there no more animals in Minecraft PE?
Explore the entire seed for two reasons: 1) I read that if chunks that generate animals haven't been "discovered," they won't spawn new animals. I walked my entire world but no new animals appeared. 2) I discovered on my tour that all the animals I hadn't killed had fallen down a hole. I tunneled them out and once I did, animals began spawning all over, including inside the fenced-in area I built. Back in the sheep shearing business!