help to avoid "inbreeding"

[Buckguy20]

I got this from the Marans of America Breeders group.

http://www.bearded-dragon-network.com/oldbvd/chart

It shows a diagram for linebreeding.
Hope it helps.

 

[patandchickens]

Guys, <biologist hat on>, halo is basically right. (Not surprisingly, since breeding chickens is not entirely different from breeding racehorses

)

Brother-sister, parent-offspring... either way, you have a similar chance of pairing up deleterious recessives.

(Mind, that is sometimes WANTED in a breeding program, so you can find out which animals are carrying that hidden allele and remove them from your program. One argument for inbreeding and linebreeding is that they "force" unwanted traits to surface so that you can actively cull individuals that are carriers.)

I realize that it is not TRADITIONAL in poultry breeding to use brother-sister pairings. But I wonder how much of that may be due to the apparent preference to use cockerels on hens, and roosters on pullets; I can imagine that double breeding (separate lines for breeding SQ males and females) could in some circumstances also argue for not using brother-sister matings.

In lab mice, you often have a lot better idea of the genotype of the parent than you do of the offspring (at least at first) so again there can be special-case reasons for using parent-offspring pairings in preference to brother-sister. Well actually this may be true to some extent in chickens as well. Plus older generations are more 'progeny tested', hence an additional value to breeding back to a parent or grandparent sometimes.

But from a simple GENETIC standpoint, they are both inbreeding and they both have the same effects.

<biologist hat off>

As far as the original question, basic animal breeding practice is to ruthlessly (er, as ruthlessly as you can bring yourself to manage) remove from your breeding population all individuals that have genetically-caused defects that you don't want to perpetuate. If you are a show breeder this could be as subtle as 'wrong number of points on comb'; if you are a homesteader it might be 'didn't start laying til age 1' or 'catches every disease coming down the pike' or 'produces unthrifty chicks'; if you are just sort of a hobbyist, it's really any ole thing that you dislike as long as it can be presumed to have some degree of genetic basis.

Also you may want to inject new blood every few generations, to improve general vigor and egglaying. One option is to introduce an outside rooster to the flock (preferably pretty closely related to your existing birds, unless you want to undo all your previous work at selective breeding); another way is to maintain two or more lines that you mostly breed among themselves but every generation or two swap a bird or two to the other group. (There are much much more systematic ways of doing it, but that's the general concept)

Have fun,

Pat

 

[Clay In Iowa]

Quote:
Now that makes sense to me. I guess I'm been dealing with Bacteria too long.

Thanks Pat.

 

[patandchickens]

Quote:
Hey, if 1 yr is equal to 7 in "dog years", just IMAGINE how many "bacteria years" you've been working with them...

Pat

 

[pips&peeps]

I am trying my best not to line breed.

Most of my flock comes from different breeders. Granted there are going to be some cousins in there, I have found that just by selecting the best birds I have had good luck.

I have been told my chicks are bigger and healthier than some of the other breeders that line breed. And, I keep two roosters of every color to diversify my gene pool. I switch them out once a year and it works for me.

 

[the1much]

apparently,, the millions of dollars worth of education didnt help the professors at the genetics lab i worked in ,, then count the millions of mice they breed that go out to every major research groups,, they must be idiots to buy their mice from jax.

 

[patandchickens]

Quote:
1much, read my post please.

The subject is complicated, and many times there *are* specific reasons for preferring one sort of mating over another. In the case of breeding lab mice, as I just pointed out, you know the parent's genotype much better than you know the F1 generation's genotype, so you have much more of an idea what you'll get (and can therefore be more likely to get what you want) by breeding parent to offspring.

This does not in any way change the fact that it's still all inbreeding and all of it has the capacity to bring recessive alleles together, for good or for bad, to be selected for or against as you wish.


Pat, former biology professor

 

[the1much]

lol,,, Pat ,, i was just ribbing clay for that useless $50,000 dollar education

needs to be mentioned too,,,, that only works for the first generation breeding, after you breed father/ daughter from his first mate, thats as far as it goes, you dont keep breeding him with his 2cnd generation daughters, cause thats where you get into recessive problems.

sorry Pat if you thought i was going against your post,, just playing

 

[patandchickens]

Quote:
Funnily enough, I was riffling through a couple books that include breeding systems for poultry to see if they commented explicitly on the brother-sister vs parent-child issue (they didn't) and ran across a couple diagrams for linebreeding systems that explicitly DO cross F2s back to their grandparents.

Pairing up recessives is not necessarily a problem... it can give you very DESIRABLE offspring as well as very undesirable ones... just depends on the situation.

It really is a complicated (and varied, depending on a lot of things) subject

Pat, with a similarly 'useless' $50,000 education

 

[the1much]

my education cost me .40 a day,,, that was fer "hot lunch's" hehehehe
then,, the lab sent me to school,, but thats useless now,, i done fergots it allz afta my accident