I wouldn't really recommend it... your DD could roll over and bury her face in the cats fur and restrict her breathing that way. Also the allergens that come with cat hair might not be the best for a little baby to sleep so close to. Another thought is that if DD rolls over and knocks/squashes the cat, is the cat likely to lash out and scratch her? I know some cats wouldn't, but then again some would...
I'm not sure if I'm remembering the wrong thing... but I *think* I have heard of protective nets you can get for cots, to stop animals (cats) from getting in?