I found this information from skinnyreport that I shared with a friend of mine.
Commercial dry ferret food is another option and they will do just fine with it. Itís important to check the label to ensure that it contains at least 35% protein from meat sources, and 15% fat. They should also be relatively low in fiber, 3% or less. In a pinch, they can be fed cat food for short periods. But because of the protein and fat levels, and other ingredients, cat food is not ideally balanced for ferrets. If you do need to feed your pet ferret dry commercial food, itís an excellent idea to supplement this occasionally with fresh, raw meat. A diet composed of natural raw ingredients is best for all animals, ferrets included.
I hope it is helpful with your problem.