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#38915 - 09/05/08 03:23 PM Re: Black chickens
IPF Offline
Coop Keeper

Registered: 04/08/08
Posts: 466
Loc: Canada
One of my posts got mislaid between here and there, and I don't remember exactly what I said. Basically, I don't think I was assuming anything with respect to generation turnover speed. I was just pointing out that mating between relatives will result in inbred offspring, and that, in general, too much inbreeding has deleterious effects on a lot of the traits that backyard flock owners care about, such as productivity and vigour. In crosses between distant relatives, like your great-great- etc example, the inbreeding coeff. will be low, and I agree that the effects will be correspondingly minimal.

With respect to your example, given that most loci segregate indepently, your conclusions will apply only to the loci you consider. Inbreeding (identity by descent) can still be accumulating at other loci governing other less immediately visible traits.

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#38916 - 09/05/08 04:01 PM Re: Black chickens
Jocelyn Offline
Lord of the Fowl

Registered: 08/26/02
Posts: 1467
Loc: Canada
Quote:
Inbreeding (identity by descent) can still be accumulating at other loci governing other less immediately visible traits.
Yes, it can; but the further back in the generations one goes, the slower the accumulation of more inbreeding. This is what conservation breeders attempt, as they wish to keep viable stock for many years and may have only a few founders for a population. Applied carefully, it does work. I have short periods of 100 percent hatch, and fairly long periods of over 90 percent hatch, so vigour is OK. I agree with your generalization though.

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#38917 - 09/05/08 04:14 PM Re: Black chickens
IPF Offline
Coop Keeper

Registered: 04/08/08
Posts: 466
Loc: Canada
Yes, I agree inbreeding is a necessary tool for conservation breeding (in poultry and other species, too). And of course inbreeding is an invaluable tool for fixing desired traits in a population - particularly those resulting from single genes of large effect, like many of the colour and pattern genes. It's not as useful, and may be detrimental, for so-called "quantitative" traits, which rely on large numbers of loci, each with a small effect. These tend to govern traits like growth rate, and egg production.
There have been some phenomenally complex and clever breeding strategies designed to maintain genetic diversity and allow accumulation of gain in desired traits, while slowing the accumulation of inbreeding.
I guess my main point is that inbreeding is a tool, and should be used for a reason; too often it's just for convenience or a reluctance to introduce new birds.

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#38918 - 10/04/08 03:22 PM Re: Black chickens
Maria Ricardo Offline
Past Moderator
Coop Keeper

Registered: 03/26/05
Posts: 434
Loc: Hawaii
Today I sold the lt Brahma X wh Rock rooster who is black. I told them the info about the wt Rock being a genetically black chicken with dominant white coloring, but really didn't understand what I was saying. Can it be explained in layperson's terms?

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#38919 - 10/06/08 09:36 AM Re: Black chickens
Heritage Hens Offline
Chicken

Registered: 04/29/08
Posts: 113
Loc: Vermont
maria, my understanding is that you shouldn't breed another color into Buff ORpingtons. I raise various colors of Orpingtons and a knowledgeable geneticist told me to keep the Buffs separate. That is, if you care about preserving the color genetics. In England the Buff are separate clubs from the black, blue, white and splash.
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Heritage Hens

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