Samantha,
 
I'm writing in response to your question, and ccing the fert list as well,
so here goes.
 
To begin with, Ferrets are obligate carnivores.  this means that they are
'obligated' to eat meat.  They have to to stay healthy.  Therefore, a diet
high in animal proteins (from chicken is preferable).  The key ingredients
in any food for ferrets are fat and protein, specifically animal protein,
since ferrets' short digestive cycles prevent them from getting enough
nutrition from vegetable proteins.  Chicken, turkey, beef, and lamb are all
fine; most ferrets don't like fish, and besides, it tends to make their
poopies stink.  The food needs to have 30-35% protein and 15-20% fat, and
animal protein should be the first ingredient and at least two or three of
the next few.  Really, a non-meat product shouldn't be before 3 or four on
the ingredient list (learn to read ingredient lists.  they're now your new
bible.)
 
Most people (and I'm not getting into an argument here, in fact, i'm
quoting directly from Ferret Central (http://www.ferretcentral.org):
"Most people feed their ferrets high-quality cat food, such as Iams,
Science Diet, or ProPlan.  High-quality food may cost a bit more than
grocery store brands, but your pet will eat a lot less and be much
healthier.  We've found that an 8-pound bag of dry food (usually $10-$15)
lasts two ferrets a couple of months, so the cost of feeding them even
high-quality food is not very great.  Because of their high protein
requirement, ferrets up to three or four years old should get kitten or
"growth" foods.  Older ferrets can have kidney problems from too much
protein, though, so they should be switched to the cat versions.
 
There is only one food I know of which was designed and feed-tested
exclusively for ferrets, and that's Totally Ferret, from Performance Foods.
It's expensive and not available everywhere.  (Call Performance Foods at
1-800-843-1738 or write them at 38251 Industrial Park Blvd., Lisbon, OH
44432 to find out the nearest distributor.) Many people feel that it's the
best food, at least for ferrets who aren't overweight (it's pretty rich),
but most people also agree that cat/kitten foods are entirely sufficient,
and that there's not that much difference between them.  "
 
Dog food is NOT OK!  Ferrets need taurine, a nutrient which is not extant
in dog food, in order to stay healthy and maintain good eyesight.  If the
fert steals a little dog food once in a while, it's not horrible, but a
high-quality (read: high-protein, high-fat) ferret or kitten food should
be their main source of nutrition, supplemented by treats like raisins and
cheerios in moderation, ferretone or ferretvite (vitamin supplements) and
a laxative like laxatone or petromalt every now and then to keep the inner
workings greased up and help the ferret pass hairballs (they can't cough
them up like cats can).
 
Things to avoid:
Although most ferrets love milk and ice cream, they shouldn't be allowed to
have much.  This is especially true for young kits, since the lactose in
cow's milk gives ferrets diarrhea, which can easily cause them to become
dehydrated.  Goat's milk, available in some pet stores, is okay.  Likewise,
I've heard that soy milk is good for them and generally liked, but I
haven't seen any verification.
 
Too much fiber can also give ferrets diarrhea, so limit raisins, bananas,
prunes, oatmeal, apples, and anything with bran in it.  Sugary treats
aren't good for them either, since they can cause dental problems.
(Despite the rumors, there is no evidence that sugar causes diabetes or
other metabolic problems in mammals.)
 
Be careful with chocolate.  Most ferrets like it, but the
xanthines/theobromine found in it may be toxic to them in large enough
quantities; nobody's sure.  It's not recommended as a treat.  (However,
many people give their ferrets an occasional chocolate chip with no
problems.) Likewise licorice -- the real thing, not the plastic, fruity,
red stuff that goes by the same name -- is surprisingly strong.  It's been
used for medicinal purposes in the past; it might not be a good treat.
Both chocolate and licorice are more likely to be dangerous to ferrets
with heart problems.  Onions, garlic, and other members of that family
can cause Heinz body anemia in dogs and cats; nobody's sure about ferrets,
or what the dangerous dose might be (the tiny bit in some meat baby foods
is probably fine), but caution is advised.
 
There, hope I haven't killed you with the info.  A lot of it came verbatim
from Ferret Central, an excellent online resource.  I put the url in
somewhere above.  Go read it. :)
 
Also, Kim Schilling's book "Ferrets for Dummies" is a very valuable
resource.  I would highly recommend it for a new fuzzy mom, or anyone
who's thinking about a fert as a pet.
 
Just my $0.02 (well, actually, more like $0.10, hehe)
 
Rhyakat
[Posted in FML issue 3317]