From:
RRC
Date: 2001-03-02 15:22:00 UTC
Subject: Re: topic - vitamin/mineral content of food
>There are
>similar NRC booklets for beef cattle, dairy cattle, sheep, goats,
>horses, poultry, rabbits, fish, mink and foxes, nonhuman primates,
>dogs, cats and laboratory animals (covering rats, mice, guinea pigs,
>hamsters, gerbils, and voles). No ferret book.
>
>The pet food industry, while not as evil as some make it out to be, has
>a pretty good thing going, and they aren't likely to spoil it any time
>soon by letting us in on the secrets. B-)
>
>Brett
Brett is absolutely correct in saying that there are no publications
detailing the nutritional needs of the ferret. There aren't any AAFCO
regulations for ferret food either (most ferret foods do not have a
nutritional claim). Outside of the table provided in the 2nd edition of
Fox's "Biology and Diseases of the Ferret" (probably the best thing you
can find in print), finding ANY nutritional standards for ferrets is
difficult. However, we can get around it because they are essentially
the same as for American mink and the black-footed ferret (the mink is
well described, and a great deal of fragmentary information is available
on the BFF). Since mink and polecats eat virtually the same types of
food (mink perhaps a bit more riverine in origin), are approximately the
same size, have similar metabolic rates, and have similar caloric needs,
whatever differences that exist would be minor.
What I have done is work from an evolutionary point of view, making the
assumption that the overall "wild" diet fulfills the animal's
nutritional needs (I have ignored dietary information for New Zealand
feral ferrets because the ecosystem is so screwed up and many of the
prey animals consumed by European polecats are not present). So I have
done a great deal of research in the foods consumed by polecats, BFFs,
and both American and European mink. Since there are body composition
tables in publication for most of the prey species consumed, I have been
able to create a chart of derived nutritional needs, working from the
prey species to the consumer.
All this does is tell you what polecats eat, and you can make nice long
lists that look quite impressive, and I have. What it doesn't tell you
is which nutrients are required, or which are essential. For that, you
are out of luck unless some graduate student does the work for their
thesis, or some researcher accepts a government grant specifying
publication of data. I am sure the information is known by various
ferret food manufacturers, but nutritional formulations are worth money
and you can't expect Totally Ferret to give their formulations away to Purina.
When I came up with Chicken Gravy, I simply made one list detailing the
averaged composition of the prey species, then consulted published
charts and tables to find easily obtained foods which would match the
first chart. Whole chickens do the job quite well, but because they are
typically fast-grown immature birds, they either are low or lack a few
nutrients. Even rapid cooking wipes out much of the vitamins and
seriously denatures some of the essential fatty acids with melting
points lower than 100 C, so a few other things are thrown in so both
lists basically match. I juggled the ingredients until both sides
matched within 95% of each other.
I do want to say something about dry ferret foods. I admit I am a well
known critic of kibbles and convinced the high carbohydrate load in dry
food is potentially responsible for pancreatic disorders (I think it
parallels adult onset, diet-mediated diabetes in human individuals who
have changed from a hunting/gathering lifestyle to a modern western diet
in a couple of generations. Look up diabetes in modern Navajos as an
example, and compare to the Mexican Navajos who still eat a traditional
diet). However, I actually use kibble, and suggest all ferret owners
feed at least some kibble to their ferrets. I do not know of a study
which proves or even suggests pancreatic disorders—like those taking
place in ferrets—is caused by dry ferret foods. Considering the lifespan
of the polecat progenitors (mean age at death = 11 months, 99% of all
age groups are 5 years old and younger, 95% 4 years old or younger),
ferrets being fed dry ferret foods are living well into their
physiological upper limits of life. This suggests that kibble isn't such
a bad food. Also, after making a serious study of all available dry
ferret foods (yes, I HAVE compared all those dumb charts and more), with
a couple of exceptions, there is hardly any meaningful difference
between them (just a couple of really bad and good ones; the vast
majority are about the same, including dry kitten food).
The real question is, "is it the BEST food?" If shifting diets away from
those rich in carbohydrates improves the quality of life of the older
ferret, I don't think that is such a bad thing. Clearly, we need a lot
more research.
In the meantime, to be honest and blunt, I am not convinced detailed
cross-comparisons of kibble amount to much because they all tend to fall
within what could be considered a standard deviation of each other. In
other words, any differences are essentially insignificant. Price
doesn't always suggest wholesomeness, so don't think a pricey kibble
will be better than a cheap one. HOWEVER, the lowest priced kibbles
include those I found to be the worst foods, and most of the higher
priced kibbles among the best. So, if you read between the lines in my
effort NOT to publicly endorse any one brand, if you don't skimp on the
price of the food, you will always end up with a good product.
Assuming kibbles are good. I still need to be convinced. ;-)
Bob C