From:
"Danee DeVore"
Date: 2010-05-06 04:45:46 UTC
Subject: [ferrethealth] reduced fighting of infection, reduced fertility, and inbreeding
To: <ferrethealth@yahoogroups.com>
Sukie wrote:
This is on humans but the ratios for increased risks of infertility
and difficulty fighting off diseases is likely to generalize to other
mammalian species, including ferrets, so people may find that
ferrets they get whose parents are not closely related may
be healthier for added reasons and this may be another health
consideration for breeders who are list members:
While it is interesting, I have some problems with this study, or at least
with the way the article presents it.
First, there does not appear to be a control group. Without a control
group, looking at the statistics of a particular family is fairly
meaningless. During Darwin's time, many families lost children to various
infectious diseases. It makes no mention of what the average percentage is
of children who died before the age of 10. If it was anywhere close to 30%,
then Darwin's family was actually average.
I know that into the early 20th century it was not uncommon for children to
die from what we now call childhood diseases. My mother's older sister died
of complications from Scarlett Fever, and her older brother died from an
infection caused from a broken leg. These were sad incidents, but not
unusual.
Next, it indicates that 3 of Darwin's' surviving children may have been
infertile, but they might also have simply married someone who was
infertile. True, with 3 there is a greater chance that at least some of the
3 were the problem, but since there was no fertility testing back then, we
have no way of knowing who was the infertile one.
What I do know is that without genetic testing, there is only one way to
determine who carries genetic defects, so that those who carry the defects
can be removed from the gene pool - and that is through an inbreeding or
line-breeding program. If members of a breeding colony are continually
out-crossed, the offspring can carry, but may not express, genetic defects.
Through line-breeding, the defects will show up fairly quickly, and those
lines that carry the problem can be removed from the gene pool.
Inbreeding and line-breeding will reinforce the genetics of the parents. If
good stock is used, the outcome will be an improvement in the offspring.
Likewise, if inferior stock is used, or stock with known genetic defects,
then the outcome will be undesirable offspring.
A carefully planned line-breeding program that uses only the best, and
removes any that show undesirable qualities will improve the species in the
long run. However, a line-breeding program that uses any or all of the
available stock without regard to the qualities they carry can cause more
damage than good.
Line-breeding itself is not the problem - the problem is how people use the
technique. If line-breeding is used to promote only the healthiest and the
brightest, than the overall results will be an improvement to the species.
There are several private ferret breeders here in the US who use a
combination of line-breeding and out-crossing in their program, and they
tend to produce some of the healthiest ferrets. Not all line-breeding is
bad.
Danee DeVore
ADV - If your ferret hasn't been tested, you don't know!
For more information visit:
<http://www.ferretadv.com> http://www.ferretadv.com
ADV - Find out how you can help:
http://help4adv.terrabox.com/
[Non-text portions of this message have been removed]
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