Young premature animals, neonatal animals, are all considered treats only and unfortunately are not adequate nutritional wise compared to adult animals when it comes to a base diet.
Neonates have lower body fat concentrations than older prey animals, and skinned, eviscerated carcasses contain lower fat concentrations than do the whole bodies of prey animals of the same age. This is not to say they shouldn’t be fed, not at all. In fact, they make perfect supplements to a balanced diet in moderation. Regardless what you feed, kibble, dry food, commercial raw or simply home made raw diets, all ferrets can consume young animals in their diet as a treat. It is very enriching and very recommended.
Treats may include, chicken and quail chicks, ducklings, Rat/Mice Pinkies, Fuzzies, Hoppers, Weaners, Rabbit pinkies, kits (the rabbit kind!), you get the idea etc. Baby animals make perfect weekly to fortnightly treats for ferrets and do aid a balanced diet in moderation.
Try to limit “treats,” as over-treating can throw a balanced diet off– regardless of the diet. I like to personally feed 1-2 baby animal treats per week or 2-3 per fortnight per ferret. How many to feed depends again on the size of the animal. Pinky to fuzzy rodents can easily be fed 2-3 times a week per ferret, but ducklings or larger poultry chicks are best fed once a week.