2.  It is safe for ferrets to consume large amounts of carbohydrates.
 
FALSE.  Fundamentally, carbohydrates are long chains of sugar, which is
why they are such excellent sources of energy.  Simplistically, there are
two types of carbohydrates: those that can be digested, and those that
cannot.  The former category includes digestible starches and sugars,
the later indigestible starches and cellulose.  Herbivores have a
digestive system modified to shear, crush, hydrolyze, and otherwise
prepare indigestible starches and cellulose for bacterial fermentation,
which takes place in the gastrointestinal tract (in various places
depending on the species).  Even so, the process is inefficient, and the
herbivore is required to eat tremendous amounts of food to meet protein
and energy needs.  The ferret digestive system lacks this ability, as
well as the colonies of bacteria that are capable of shearing the
molecular bonds found within indigestible starches and cellulose.  In
short, ferrets are incapable of digesting most vegetable materials.
However, during the extrusion process, hard to digest starches are
converted into easily digested ones.
 
Ferrets are animals that generally eat to meet energy needs, which means
they eat until several physiological mechanisms are triggered.  Here's a
puzzle for you; why do ferrets that consume meat only eat a few times a
day, while ferrets that crunch kibble will eat every few hours?  The
answer is simple: starch.  Starch causes blood sugar fluctuations that
spur feelings of hunger.  The mechanism is simple, relating to blood
sugar levels as well as the presence of a hormone, CCK (cholecystokinin).
 
As the kibble bolus is hydrolyzed in the stomach, the resulting chyme is
squeezed through the pyloric sphincter into the duodenum, resulting in
the production of CCK.  The gall bladder and pancreas are stimulated
into releasing bile and pancreatic juice.  Pancreatic juice contains
bicarbonates and digestive enzymes, including lipase, protease, and
amylase.  Amylase is an enzyme used to break starches into complex sugars
that are further hydrolyzed by specific enzymes, such as maltase, or
lactase.  The presence of starches in the intestinal mucosa causes
additional excretion of CCK, simulating the external secretory activity
of the pancreas, especially the production of amylase (CCK has several
other functions beyond the scope of this discussion, including specific
effects on satiety, and the stimulation of other digestive enzymes).
 
The reason ferrets that eat kibble have to eat so frequently is
threefold.  First, kibble swells as it starts to be digested, so it
doesn't take a lot to fill the stomach, triggering feelings of fullness.
Second, as kibble is digested, it drastically raises blood sugar,
reinforcing the feeling that hunger has been abated.  Third, as the
kibble-derived chyme enters the duodenum, it stimulated the production
of CCK, which triggers receptors in the brain, shutting down the hunger
sensation.  When ferrets eat meat, because far less starch is present,
this process takes much longer, so they eat more.
 
Here's the rub, and why high levels of starch isn't particularly
healthy for ferrets to consume on a regular basis.  Ferrets that eat
kibble are making the acini cells of their pancreas work overtime to
try and manufacture enough amylase to convert the excess starch in
their intestines into complex sugars (disaccharides: lactose, maltose,
sucrose).  That's the first domino.  Complex sugars are converted into
simple sugars (monosaccharides: fructose, galactose, glucose).
Ultimately, all starch-derived sugars are converted to glucose (also
called dextrose, blood sugar, corn sugar, or grape sugar).  What this
means is ALL the digested starch in kibble is ultimately converted into
glucose (blood sugar).  That's the second domino.  Blood sugar levels
are controlled by the pancreas, which excretes insulin and glucagon to
maintain a constant level.  Insulin is released when blood sugar is
elevated and glucagon when blood sugar is depressed.  The question is,
how does a pancreas that evolved specific modes and rates of excretion
of enzymes and hormones designed for an all meat diet respond to a diet
suddenly rich in starches?  That is the million dollar question, and the
key to understanding insulinoma.
 
The bottom line is the ferret digestive system evolved supplying enzymes
and hormones to a meat-eating specialist.  It was not designed to process
the large amounts of carbohydrate present in contemporary dry, extruded
foods (kibbles).  Is this a triggering event for other disease processes,
or a direct cause of insulinoma?  That question is unknown, but there is
little doubt a correlation exists between consuming kibble and increased
rates of insulinoma, as to obesity.  Even if the question of insulinoma
cannot be answered, the fact that frequent feeding of a sugar-rich food
directly leads to obesity, and THAT by itself makes the feeding of starch
to ferrets unhealthy.
 
Bob C
[Posted in FML issue 3938]