I'm not sure that diet necessarily has an effect on coat/weight changes
during season changes.  Sometimes our little ones grow a winter coat and
gain weight and sometimes they don't, with no diet change.  This year is the
poofiest yet.  Everyone seems like they have gained a pound and grown their
fur out an extra couple inches.  Last year, no one got a winter coat except
Clarence.  And, it seems to me that Edith gets a winter-do every-other year.
Maybe it is each individual ferret's sensitivities to the changes in the
light and the temp each year.  I think it depends a little on when the
beastie was born too.  It seems to me that if your ferret was born after the
winter season begins to darken and get colder he won't get a winter coat
until he finishes that season and goes through another one.  For example -
if your ferret is born in March - she might get a winter coat in Oct/Nov.
But if your ferret is born in November - you'll have to wait nearly two
years to see a coat change.  This is all conjecture from observatio n of my
ferrets...  I have no idea if it is true, it just seems like how it works in
our family.  Charlene
[Posted in FML issue 1398]