Check the "ingredients" list.  You'll most likely find "corn" or "soy" or
a "gluten meal" listed within the top 3 or 4 ingredients.
 
These vegetable ingredients contain protein... but it cannot be digested
by ferrets.  Ferrets are obligate carnivores.  Their digestive tract is
not designed to extract nutrition from vegetable sources.
 
So that 40% protein is only (maybe at most) 30% animal protein that is
nutritional for ferrets.  Since the extra vegetable protein cannot be
digested, it passes through as poop without placing an extra burden on
kidneys.
 
(I'm not a nutritionist, so this is a fairly broad explantion!)
 
http://www.totallyferret.com/nutrition.html is a very informative article
on ferret nutritional needs.  Even though it's written by Tom Willard who
(understandably) pushes his brand of food, the fact remains that he IS
the ONLY one who has done any REAL and documented research on ferret
nutritional needs.
 
Debi Christy
Ferrets First Foster Home
 
Practical & easy training, care, & maintenance articles available at
http://www.geocities.com/ferretsfirst/
[Posted in FML issue 3668]