Animals Disappeared

I Saved and Exited my world, turned off my Xbox and went away for a bit.

Some time later, I turned my Xbox back on, started Minecraft and went in my World, all the animals I had (there were a lot) apart from a few bunnies have disappeared completely, Horses, Llamas, Cows, Chickens and 7 Dogs. 

I don't have a copy for it... Is there anything that can be done or I have to look for everything again?