animals don't naturally spawn in amplified worlds.

When I'm playing survival in 1.9 pre3, in the beginning i have killed out all of the animals in my region where my base it. i am in a plains biome and when i started it had allot of sheep, pigs and chickens. now after i killed them out new ones don't spawn. i have been in that region for over 15 hours an there were no new spawning. according to Gamepedia (Minecraft wiki), animals will not spawn within 24 blocks of a spawn-point (active bed). but even so after 20 blocks nothing still spawns. the other players on the server are having the same issue.