I am sure others have responded to you by now but wanted to agree in part
with Vivian Barnes from the FML.  While I don't think that MF food is bad
for them and that MF is out to "make money and sell the cheapest made
stuff", I do feel that their food might not be as good as others.  Here
is why...
 
I ferret sat 4 ferrets for 2 months.  They were eating MF food.  They
were fat.  At first I thought it was just because they didn't have much
free time outside of the cage.  But then I watched them for about a week.
They were just so tired.  They couldn't run very far and would have to do
the "speed bump" every couple of minutes.
 
Now, they were only suppose to be there for 2 weeks....but that turned
into 2 months.  Because of this, I ran out of their food and I was not
going to buy special food for them (I was not going to be reimbursed for
their care or food...this I already knew...plus didn't know if the owner
was coming back).  When their food got low I started mixing it with our
food, which is a combination of different brands - 8 & 1 Ultimate, TF,
Sheppard and Greene, cat food (very small amount), Zupreem, and another
one that I just can't think of right now.
 
Guess what?  They started to play more and run around more...and they
lost weight.  Not a lot...but enough to allow them more energy.
 
Now, here is the other thing....it might not have been the food at all...
their owner was also giving them beef jerky every day.  Yep, regular
people food beef jerky.  Nope, I didn't give them any.  WAY TOO MUCH
Sodium.
 
So, was it the food or the beef jerky?  I think it was a mix of both.  I
do know that with MF food their poops smelled worse.
 
Try mixing other foods into the MF and see if that helps.  It is also
an easy way to phase them off of MF food.  Sometimes ferrets over eat
because they are not getting the nutrients that they need.  So they eat
and eat and eat.  It might also explain why your other ferret is so
skinny.
 
Another reason to have several types of foods mixed is in case one
company changes ingredients or stops making that food.  Then your ferret
could starve himself by not eating any other brand or flavor.  Always
something to think about for everyone.
 
On another note though...my Dodge is about 4 pounds.  He is very large.
He can't fit in tubes anymore (well he can but when it gets to his back
end he takes the tube with him...it is kinda funny!).  He is just big.
He is very healthy and plays just as much as the other 7.  He is now 8
months old.  He went through a growing phase at about 6 months and that
is when all of the weight came on.  He looks healthy and happy and eats
a little more than the other ferrets.
 
Hope this helped.
 
Joanne
[Posted in FML issue 3852]