I have a barn cat who had a litter of three kittens.  I placed her in
a shed where I have another mother with older kittens.  The next day
one kitten had died.  I removed the dead one.  The following day
another kitten was missing, and I could not find it.  The third one
seemed to be doing ok, and its eyes were just starting to open.  This
morning I go in there and find the kitten alone, and real cold.  I put
it by mother cat, and she just walks away from it.  I took the kitten
in the house, and bottle fed it some milk.  Later in the day it looked
better, and I bottle fed again.  However, I had to go away for quite a
few hours and thought it would be best with mother, rather than alone.
I placed mother cat and baby in a metal cage, and put the cage in the
garage where no other cats could get to them and bother them.  

I just came home, ready to bottle feed the kitten again, and find it
is completely gone.  Not even the slightest trace left.  There is no
way it got out of the cage, and I moved all the bowls and paper in the
cage.  All that remains is mother cat and her food and water.  She
must have eaten the kitten.

Is this possible?  If so, why would she eat her own kitten?  
(She has a whole bowl of food, so she is/was not starving)...

Mark