[Jacob-list] breeding

[linda]

I realize that one "good" inbreeding experience does not prove anything.  Nor does one "bad" 
inbreeding experience.  I'm sure that if I continued to select for slipped eye patches, using 
animals with the trait, whether inbred or not, I could set that trait to the point that all my 
sheep would exhibit the trait.

Many people told me how the light facial markings could be so easily set in a flock.  I wanted 
to see if I was necessarily going to do that using this ram.  As the vast majority of his 
lambs have quite acceptable, large face markings and I didn't get slipped eye patches when 
trying to - I feel comfortable that I won't end up with white faced Jacobs just by using this 
boy for a few years. And I am very glad that some terrible recessive trait didn't show up - 
although I know that this breeding does not mean the genes are not there. I realize that this 
breeding experience means nothing using the scope of the "big picture" but I'm only working on 
the "little picture" here.  I am not advocating inbreeding.  It's a tool like any other tool 
to be used for some purposes and with caution and intelligence.

I would be curious as to how many sheep with a coefficient of 22% did not have Twinkle Toes.

Linda

On Fri, 6 Oct 2000 16:46:15 EDT,  wrote:
>Marcia is right on with inbreeding...the best and the "wurst".
>
>We have noticed that there is a higher incidence of structural and genetic
>problems as inbreeding coefficients increase.  For example:
>(1) we bought a pretty yearling ewe about three years ago, coefficient was
>about 25% (we idn't check the pedigree closely!).  Barren after three years.
>(2) loose ram produced Twinkle Toes, coefficient 22%.  No hoof walls, xray
>showed missing digits in feet.
>(3) in general we have observed coefficients over 15% tend to result in
>"shorter, smaller" Jacobs; offspring also tend to be small
>
>An inbred ram should help to "fix" traits but it takes many generations to
>"fix" a trait and see true repeatability; homozygous at virtually all alleles.
>
>Others that have actual experiences such as these might shed some light on
>successful inbreeding for several generations.  One "good" inbreeding does
>not stand on its own.  Breeding two with high coefficients with a lower
>cofficient offspring would be preferred to increasing inbreeding.  "A
>Conservation Breeding Handbook" may be helpful.   Fred Horak
>
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