Problems with terrain generator and mobs spawn

Hello.

I start lots of new worlds with the new snapshot 1.6.2, and i cannot found sheeps in another place than jungle. I cannot see sheeps in Plains, Mountains, Forest, Tundra, etc, only in jungle.

And i see cows in the place of sheeps. In 1.5.2 cows only appear me in hills and high mountains, tundra and swamp, but now i see in plains, forest, rivers, deserts.

What's happen? thanks.

Update: Errr, i think i have a problem with the terrain generator. (See screenshot below)

Update 2: I redownload launcher and minecraft and the problems continues.