Ferrets cannot - and I repeat - CANNOT be vegan. They are strict carnivores and cannot digest plant food because of their short gastroinstestinal tract. They need to eat meat and plant products can actually kill them. Please, please for the sake of your ferrets health either feed it meat or give it to someone who will be responsible. Otherwise, it will get sick and die. Feeding it a vegan diet is exceedingly cruel and very detrimental to their health.
If it is healthy now, it won't be for much longer. Of course it is going to look more healthy now than when it was neglected by its previous owners, but that doesn't mean what you're doing is right for the ferret. It's a form of animal abuse and if it continues, your ferret will die prematurely.The vegan pet foods I've seen online for ferrets contain many plant ingredients that are toxic to their digestive systems. Do some research and understand that they require meat and cannot digest plant/carbohydrate matter:
http://www.ferret-world.com/vegetarianferretfood.html
http://www.ferret-world.com/healthyferretfood.html
http://www.peta.org/living/companion-animals/caring-for-ferrets.aspx
http://www.helium.com/items/1183902-feeding-ferrets
Even PETA say ferrets have to be fed meat!!
You have proven that unfortunately you're not feeding your ferret a correct diet: baby food consisting of fruit or veg is appalling as a ferret cannot digest either of these things. Furthermore, vegan cat food is incredulously bad for a ferret as it contains vegetables and carbohydrates that they also cannot digest.
Feeding a dog, and to some degrees a cat, can definitely be done safely and healthily. A ferret is a completely different story (and anyone debating that evidently has not done their research).
What I have written here is not my opinion. It is scientific and undeniable fact, and I'm incredibly sad that you refuse to see how harmful you are being.