[Jacob-list] color- rookie question

[Neal and Louise Grose]

In some 20 years of breeding these creatures, I have come to the conclusion that the term "some simple rules of thumb " should be excluded from our vocabulary. Genetics of color is very complicated, and there is also a substantial amount of random variation at work. Color patterns seem to have some basic genetic guides, but the pigmentation assignment occurs relatively late in the embryo development, similar to the way our fingerprints develop. Identical twins, clones, and even split implanted embryos have been shown to vary quite a bit in appearance. Given a ram used on a group of genetically similar ewes, you could still expect + or- 20% from the average in the lambs. The only way to get consistent results is to inbreed over several generations...NOT something I would recommend. (But if you really need to, use sibling crosses, not the "use the old geezer 'til he croaks" method.)

Neal Grose
  ----- Original Message ----- 
  From: Brenalan Farm 
  To: jacob-list at jacobsheep.com 
  Sent: Friday, July 20, 2007 12:11 PM
  Subject: [Jacob-list] color- rookie question


  Hi, everyone! This is my first posting and my second year of Jacobs. I really enjoyed browsing the archives and learned a lot. Thanks for sharing!

  I have done some reading about the genetics of color but am looking for some simple rules of thumb or practical experience regarding prediction of % color. I have seen % ticking/ size of piebald areas in a few litters of dogs (where # of offspring/ litter was 10+) and it seems pretty random within the litters- darks and lights. I was surprised at how dark a couple lambs were this year. Let's not consider crossbreeding in recent generations... I am not too good at gauging % black and white, but was thinking I was taking two 30% black parents and getting half 60-70% lambs and half about the same as parents. None that were lighter than parents. To complicate the question, I only had 4 lambs that I bred, so this might just be random. I feel like I am trying to predict the next card in the deck based on one blackjack hand! Even if I had all the flock books, I am not sure how to weigh the color of sheep in pedigrees vs. what to expect in the next generation. To tell the truth, it looked pretty random and left me thinking I should prioritize for quality of fleece and head. But- since I have some lambs that are pretty dark I don't want to make mistakes that would push my genetics too far towards that end of the spectrum. The basic question is: Does one generation substantially lighten or darken a flock, or do you change percentages gradually over several generations? Anyway, thanks in advance for whatever advice you can share.

  Brenda
  ---
  Brenalan Farm
  Toledo, Oregon
  541.336.2158
  www.brenalanfarm.com


------------------------------------------------------------------------------


  _______________________________________________
  Jacob-list mailing list, sponsored by Swallow Lane Farm & Fiberworks
  Jacob-list at jacobsheep.com
  http://www.pairlist.net/mailman/listinfo/jacob-list
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.pairlist.net/pipermail/jacob-list/attachments/20070720/58316102/attachment.html>