Feeding them dry food helps keep their teeth in excellent condition. Canned food tends to go bad too quickly for the feeding habits of ferrets. Ferrets should never be given any chocolate as you will find your ferret vomiting violently all night or perhaps dead. Chocolate is very toxic to ferrets. They are also lactose-intolerant, so do not feed them milk, ice cream, cheese or other dairy products, no matter how much they beg.
Ferrets can ingest goat's milk since it contains little lactose.
Things made from goats milk should be fine for your ferret. Do not feed your ferret dog food or sugary sweets.