It's closest to their natural food minus the bones. I got it from this website Making Cat Food, which was mentioned on one of the threads in this forum.
That website is a great resource. Our cats eat the same combination and in their 3 years so far, they've only had three hair balls between them and the vet said they are as healthy as kitties could be.
Eventually you may want to go whole hog and get a food grinder so you can use fresh bone as the writer recommends. The Tasin TS-108 Meat Grinder is terrific and will grind chicken bones without voiding the warranty. I make a triple batch of the recipe, freezing it in portions that equate to two days of feeding. A triple batch lasts about about three weeks here (they are BIG cats). The grinder has more than paid for itself, not only in not having to buy commercial cat food, but in knowing exactly what our sweeties are getting.