Well basically, the chicken mob's animation was stuck on an infinite loop of it's falling animation (Where the mob flaps it's wings wildly).

I created a new singleplayer world (Default) to test the snapshot, when I noticed a chicken stuck in an animation loop.
At first, I thought that this was just a bug with one chicken, but as I looked around, every chicken that I saw was doing the same as the first.
I then began to think that it may have something to with chunks having to load properly, but everything else in the game was functioning like it should.
I decided to try and reproduce this bug by making a new world, and the same results were found.
This bug is in no way an exploit or game threatening, but its is very off putting and would very much appreciate it being fixed.
Thanks,
Dugcraft.