Aart, I’m sure you know that every chicken breed was developed by inbreeding. Every championship show chicken was developed by inbreeding. Every championship line is maintained by inbreeding.
Genetic diversity is the issue, of course. For show quality chickens you want to eliminate any genetic diversity in what the judge sees. That’s how you eliminate flaws, get rid of any genetic diversity that creates anything you don’t want the judge to see. But you don’t want to get rid of the genetic diversity that would cause sterility or other problems. It’s kind of tricky.
When you are developing a breed or a line, you usually use line breeding, mating a parent to its offspring. If you cross a superior bird with its offspring you enhance the traits that make the bird superior. If you cross siblings you do not get that specific enhancement, it’s more random. That’s why line breeding instead of sibling breeding is usually preferred.
I had a conversation with one of the top geneticists on this forum about this. There are a few qualifications, there always are with chicken genetics, but the loss of genetic diversity is no different in crossing siblings than it is with crossing parent/offspring. I’ll say it again. The reason line breeding is emphasized instead of sibling breeding is that line breeding better enhances certain traits.
Once you get your line established though you want to maintain as much genetic diversity as you can without losing the traits you have enhanced. There are different techniques you can use. Hatcheries use the pen breeding method. If you put 20 roosters with 200 hens and select your breeders from their offspring you can maintain pretty good genetic diversity. That’s not how you develop or maintain show quality traits though. Breeding is too random. But it works for mass produced hatchery quality stock.
One method show quality breeders use is spiral breeding. If I were Lewis77 I’d divide the chicks that hatch into three sub-flocks, probably by marking with wing or leg bands. Toe punching can work. Let’s use the designation Flock A, B, and C. At breeding season I’d put the best rooster in Flock A over the best hens is Flock A and do the same for B and C. The first year it doesn’t matter. The next year I’d put the best male offspring of A with the best pullets or hens of B, the best male of B with C, and so on. Once you get the cycle established you wind up breeding second cousins.
There are tweaks to this. Some may not breed pullets and cockerels but instead wait a year and breed hens and roosters. If a breeder trusts another breeder they may swap roosters every four or five generations to really boost genetic diversity yet maintain the show qualities they are breeding for. Once Lewis77 gets into showing he’ll have a chance to talk to real experts in this. Some are kind of jealous and don’t want to help the competition but many are so passionate about their chickens they love helping others. I’d suggest that he start going to shows as soon as possible, partly to talk to the experts but mainly to start the learning curve of what qualities he wants to look for in his breeders. Joining the State or National association of Jersey Giant breeders would probably be a good idea too.
There are other methods than this too. I’m just trying to give a general idea of one way I’m aware of.
