Sure, but they can still cause gas or the runs. The ends of chicken bones, pig or beef ears, etc., are all made of cartilage, which is often used as a homopathic remedy for joint pain. I am personally convinced that one of the reasons ferrets love to chew on rubber and crunchy veggies is because they have a sort of cartilage texture and chewiness. I just soak them until soft and cut them into strips. Providing this type of chewing pleasure, as well as bones, has almost completely eliminated rubber and cord chewing in my house, even from Ballistic who would chew the heels off your shoes while you were wearing them.
Cartilage is mostly protein, low fat, but as a treat, it is excellent.
This is mostly cellulose, complex carbohydrates and simple sugars, but most mammals love them anyway. You don't run the risk of a bowel obstrction like with hard crunchy veggies, but the ferrets will only absorb the sugars as the rest passes through. Ok as small occasional treats. Mostly fat, and most of the lactose has been removed. I rarely give cream without mixing it with something else, such as creamed chicken.