I got 2 ferrets about a week and a half ago and I went out and bought a 25lb bag of food for them. Both ferrets are female fixed and descented. I was told that the albino is 1yr and the sable is 2 yrs. But I am not sure. I let them out of their cage 3 times a day for an hour each time and they are litter box trained. I also plan on buying them a bigger cage the one I got with them to me seems too small. So i have a couple questions

1. How much food do ferrets eat in a month?
2. how can you tell how old they are?
3. the albino has fur missing from her tail what could cause this?
4. how much should they weigh they are both really skinny?

I am going to buy a book on ferrets I thought I read up on them as much as I needed but I guess I was wrong. Any one have any ferret books they can suggest?