Comments about Brown's Nutrition Plus Ferret Food:
Ferrets are obligate carnivores. Seeds and grains are not easy for them to digest, and they need a far greater ratio of fat. The guaranteed analysis of a ferret food should include more than 20% crude protein, and more than 20% crude fat.
Your ferret may like this food, and it may be fine for an occasional treat, but it shouldn't be their main diet. It looks like the vendor is re-targeting food meant for herbivores (rabbits) for ferrets.