Linebreeding/Inbreeding - how much is too much?

[Michael99]

Does linebreeding work to maintain a line if all the birds within the line were related to begin with? Or does this only work if the two original founding birds were from different lines and not related?

I have a group of Phoenix bantams, and the original pedigree is as follows - the original rooster I got was breed with his daughter and 3 of his nieces (so the pullets/hens were bred to their father and or uncle), and I kept some of those chicks from last year to breed this year. My question is can I continue breeding the pullets from subsequent hatches back to the original rooster for maybe another 2 or 3 generations, and do the same with the hens and subsequent cockerels, and then eventually cross the two lines back to each other? Or will this not work because they were all related to begin with?

I know this is linebreeding (which usually works no problems), but all of the birds that I started out with were related to begin with, so I'm not sure if I can realistically do the cross after 2 or 3 generations, or if by that point I should be bringing in another bloodline. I want to hear from experienced breeders, or people who managed to keep a closed flock of a few birds for many years without having to bring in new bloodlines.

 

[sourland]

A friend of mine started a family of WCB Polish from one foundation pair. He had extremely good show birds but eventually hatchability and fertility were severely impacted. I incubated eggs for him, and almost all chicks had to be assisted hatch. Roosters generally became infertile at 2 or 3 years old. There are systems where you can breed multiple familial lines to utilize for keeping/improving vigor, but this needless to say requires larger numbers of birds.