My guys get very few treats...the occasional "Snaffer" chicken-based
treat, and an occasional dollop of hairball goo, which they seem to love.
Why?  Because the food I give them seems to satisfy them to the point that
they don't look for treats.  What do I feed?  Whole chicks, mice, small
rabbits, turkey pullets, and the occasional quail egg....they do
fantastically well on it.  Personally, I would never give any fruit-based
treat and especially nothing with peanut-butter or marshmallows..I can
hardly think of anything much more distant from a Mustelid's natural
diet... I am not surprised that people are reporting blockages.
 
Remember, a few thousand years of domestication is a tiny blip on an
evolutionary/adaptive timeline....nowhere near enough for ferrets to
adapt to a diet any different from that of their ancestors.
 
G. A. Christian Bilou
[Posted in FML issue 3603]