Extremely thin cat

My cat is an outdoor pet. She is approx. 2 1/2 years old. She has recently given birth to her second litter of kittens and she is so dangerously thin that I can see her ribs and her hipbones and I can feel her spine. I am very worried that since she is nursing the kittens she is getting no nutrition for herself and is in danger. She doesn't like the cat food that I give her anymore and instead prefers to hunt for her meals eating lots of mice, rabbits and birds. Will she be okay?

Answer by Kate
It is importnat that a nursing mother has all the nutrients for herself and to pass on to her kittens. there are special cat foods designed for nursing cats, you could try one of those (there is an example of one here on my cat food page http://www.our-happy-cat.com/cat-diet.html )

If her weight dosn't pick up then a trip to the vets might be in order.