[Jacob-list] Answer about a white lamb

[Mary McCracken]

Great Idea!!
-----Original Message-----
From: Chovhani <melanie.boxall at sympatico.ca>
To: jacob-list at jacobsheep.com <jacob-list at jacobsheep.com>
Date: Monday, April 17, 2000 7:38 PM
Subject: Re: [Jacob-list] Answer about a white lamb


>Forgive me, but isn't this perfect example of the benefits of registering
>all Jacob's, even the flawed ones, so we can keep track of genes? If there
>are too many objections to recording Jacobs as they are (rather than as we
>would like them to be), why not a separate class for "imperfects" just to
>keep track?
>Melanie
>
>http://earthhome.tripod.com - Family & Home - NEW UPDATES!
>http://www.geocities.com/Athens/Aegean/4838 - My Spiritual Website, updated
>and re-organized, but not QUITE finished!
>
>"I'm not having a mid-life crisis, I've always been this messed up."
>----- Original Message -----
>From: <Jacobflock at aol.com>
>To: <hettick.1 at osu.edu>; <jacob-list at jacobsheep.com>
>Sent: Monday, April 17, 2000 8:10 PM
>Subject: [Jacob-list] Answer about a white lamb
>
>
>Fred Horak substituting for Joan who is out of town and isn't on the
>machine!
>
>The questions in this post about an all white lamb:  The post asks (1) what
>about the purity? (2) is it a sign of cross breeding? (3) All are JSBA
>registered..if JSC would white disqualify one or both his parents?
>
>Might it make sense to rearrange some questions to get to the genotype?
>
>(1) Genotype questions first.  Let's look at the White lamb...Any black at
>all..nose, hooves, horns, spotted tongue, nape, eye ring like eye
>liner....etc. evidence of the presence of a recessive ss piebald gene.  All
>you need is a BLACK spot to "suggest" it is DOMINANT BLACK, and recessive
>ss.
> The last places for black to remain before disappearing is nape of the
>neck,
>a miscule eye ring or face spot.
>
>Look at the parents and the percent white for the sire and dam,  then look
>at
>the percent white for the sire's sire and dam... and the dam's sire and
>dam...and then go back one more generation so you have the lamb back to
>great
>grand parents. The benefit of registration is the pedigree information.
>Next
>calculate an inbreeding cofficient for the lamb, then the sire and dam.  IF
>the lamb or sire or dam's coefficient of inbreeding is greater than 10%
>perhaps even approaching 15%, the culprit is probably inbreeding (it brings
>out the best and the wurst).
>
>If the coefficient for the lamb or its parents is not greater than, say,
5%,
>see if you can find siblings with complementary (not to be confused with
>complimentary) distorted color ratios.  Very often the amount of white and
>black is reversed between sets of lambs...one twin might be 90% black, the
>other 10% black...opposite looking "twins".  Since these are registered
>there
>should be a clue in the closet unless only the one complimentary "twin"
(not
>the wurst) was registered.
>
>Just recently I had an opportunity to see a 95% white lamb with 95 %
parents
>and each of the three had coefficients between 10 and 16%.  The inbreeding
>"fixed" the extreme white piebald recessive.  The question long term is how
>to breed out of the extreme white piebald.  One way, if you are confident
of
>the genotype of the current lamb's sire and dam, is to breed each to a dark
>piebald.  The expected result for the first generation is 50-50 and each of
>them could produce an extreme white or dark piebald.
>
>The various s (piebald) alleles are heterozygous and are very complex.  You
>can selectively breed toward white or black but through the various
breeding
>generatons the breeder will see a lot of variation.  Remeber it is the
>piebald s that makes the dominant black (Ed) have spots.  Culling extremely
>(white or black) marked single offspring takes the apparent culprit out of
>the gene pool but the parents are the carriers.  The worst scenario is
>culling an extremely marked twin and placing the normal colored into
>production...it probably carries the problem forward with a 50-50 chance of
>expression in the next generation.
>
>(2) Hard questions next.  Lamb, dam or sire highly inbred? Yes, switch dam
>and sire.  Get out of the inbreeding loop.  Not inbred?  Send it in anyway
>as
>a record of the parents progeny not for purposes of registration for
>breeding
>purposes.  Can you repeat the breeding...time issue?  The record of
>subsequent progeny may help verify the genotype of the sire and dam.    The
>registration of the dam and sire is an accomplished fact. Virtually no
>registry for any breed (or species?) has a mechanism to "unregister" stock
>save the Cotswold(?).
>
>Now, with the white lamb (which does not meet the Breed Std.) the breeder
>has
>to make a judgement as to how to proceed.  If not inbred, why is the white
>thus expressed?  Switch ram and ewe to a different ewe and ram.  If at some
>point the extreme white piebald reappears, you should have the suspect
>carrier.  The suspect carrier should be dropped from breeding ...and any
>relatives producing extreme white.  Can you borrow a ram or another ewe and
>experiment?
>
>(3) The first question on "purity" or "cross bred", when looking at
>registered animals with known pedigrees, is generally the last test
>question.
> When buying livestock of any breed, you have to trust the ethics of the
>seller (1) see the whole flock (2) sire and dam (3) brothers and sisters
and
>(4) the family tree.  If "impure" or "crossbred" it will show up or there
>will be "unknowns" in the pedigree.
>
>
>
>
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