Ferrets are obligate carnivores. This means their natural diet is strictly meat or whole prey. Their digestive system is built to process meat, organs, bones, skin, feathers, and fur.
So when choosing a diet for your ferret, or picking out the best treats, stick to a high-quality dry food consisting primarily of meat, that contains minimal or no grains and vegetables. Some owners even choose to go the route of feeding their ferrets pre-killed or live prey.