>From:    Adrienne Boerger <[log in to unmask]>
>Subject: Breeding
>Regarding breeding as a hobby.  I am a little shocked at the number of
>people who decide to breed puppies/ferrets/whatever when there are so many
>of these in shelters needing homes.
 
And what number is this?  In the more than one year I've been on the FML, I
am the only person I can recall posting questions about starting up a
breeding operation.  The only other small breeder that I know irl stopped
after one litter (which he successfully placed in excellent homes).  This is
animal rights propaganda and it's straight out of PETA doctrine.  I suggest
that people don't take the trouble to argue with this viewpoint, because it
is marginal.  Sorry if I have offended, but I don't particularly like being
accused of being irresponsible and selfish, either.
 
On Marshall Farms and culling cancerous lines:
 
I promised to unearth my old genetics textbooks to bring everyone a lesson
on population genetics, since the idea keeps cropping up that Marshall Farms
should select cancer out of its lines.  First of all, I would like to read
about any other breeders that are following this kind of program,
specifically, following every offspring through it's lifetime and then
culling the line if there are problems.  It is a larger task than it sounds.
Second, I thought it would be interesting to discuss the Hardy-Weinberg
equilibrium.  This is an equation, stating that:
 
p^2+pq+q^2=1
 
where p and q are dominant and recessive allele frequencies (ie, A and a).
The equilibrium equation states that the frequencies will remain stable
through the generations in the absence of natural selection and things like
genetic drift.  The reason I bring this up is that H-W has been used to
debunk the philosophy of eugenics in human beings (Adolf Hitler being one of
the more outspoken proponents of eugenics), and the same argument could be
applied to "eugenics" in ferrets, UNDER CERTAIN CIRCUMSTANCES.  Those
circumstances are when the recessive allele is extremely rare, recessive,
and harmless in the heterozygote.  In this case, contrary to intuition, it
is almost impossible to rid the population of that allele, because the
proportion of heterozygotes to homozygotes increases.  For example, take the
case of a harmful allele a which can be observed in the homozygote aa, but
not the heterozygote, Aa.  If the frequency, q, of the a allele is 0.0001,
then it will take roughly 2500 years to reduce the frequency q by half (to
0.00005) [human lifespan,not ferret].  Thus, you can see that eugenics
programs to eliminate very rare congenital disorders, even by culling the
"parents" are complicated by the invisibility of the recessive allele in the
heterozygote.
 
Now, how does that apply to Marshall Farms?  Firstly, I should say that I've
seen several of these debates go the rounds and no one has ever produced a
single piece of evidence that MF ferrets suffer from any disease at a higher
rate than any other ferret population.  Also, my understanding of the
Marshall Farms closed colony situation is that breeding stock goes IN but
does not come OUT, and the size of their operation is such that we should
see no more homozygous recessives than any other normal population.  Now, if
MF is rampant with cancer, adrenal disease, insulinoma, retardation, and
whatever other defects have been attributed to them, it should be no problem
to reduce the frequency of those genes because the frequencies are so high.
On the other hand, if the gene frequencies of defects are anywhere near
those of other ferret populations, then they are probably pretty close to
that 0.0001 mark and you're talking about centuries of boggling
record-keeping to reduce them even a little.  Then add to that the
complication that only a few cancers are actually caused by genes, and most
are simply an occupational hazard of using a genome composed of nucleic
acids.  I think it is unfair to criticize Marshall Farms on this count.
 
My whole point is not to "flame" anyone, but to point out that population
genetics is not an armchair discipline.  Also, I would like to see the
Marshall Farms criticisms include more concrete evidence, and less
speculation and rumor.  One of the previous times this debate went around,
we actually had someone post a letter written by someone from Marshall Farms
denying many of the accusations that I keep seeing.  Is it still out there?
I'd like to see something from the other side.
 
I can't believe I got into this debate AGAIN.
 
-Catherine Shaffer
[Posted in FML issue 1703]