I am a contrarian when it comes to the genetic make up of the dark laced blue birds. I\'m going to stick my neck out here and see if it gets chopped off. I don\'t think the blue birds have Co columbian or Pg pattern gene. I don\'t have empirical evidence to support my claim, but here is some of the circumstantial evidence.
1. Here is a link to a photo of a blue old english bantam
http://www.bantamclub.com/gallery/displayimage.php?album=4&pid=108#top_display_mediaDecent lacing if not quite up to Blue Andalusian standards.
Blue Old English Game bantams do not have Pg. If Pg was floating around the gene pool of the Old English Game bantams I am certain that we would have laced and spangled varieties by now. The only laced Old english I have seen were developed by bringing in Sebright Blood. Same with Columbian. I remember just recently when they were developing the Columbian Old English. They had to outside the breed and it took many years to get them to the proper OEG type.
2. This next link is for a Blue Partridge brahma
http://norfolkbrahmas.files.wordpress.com/2012/03/3rd-march-2012-0041.jpgAlmost by definition, Partridge birds have the Pg gene. If Pg is responsable for the lacing in blues then a blue partridge should have excellent lacing on the blue parts. This is a beautiful bird (the male) but not much lacing on that blue breast.
3. Third is a Blue Laced Red Wyandotte
http://www.backyardchickens.com/t/105208/blrw-picsWhat is the difference genetically for a blue laced wyandotte vs the definition proposed above for a dark laced blue bird?
To me it looks like they are describing the same bird.
The assumption that Carefoot makes is that there is only one way to make a laced bird. We know that there are more than one way to make white birds. There is more than one way to make a black bird. There are several ways to make a black breasted red bird. So why would we assume that there is only one way to make laced birds?
I am not sure what is the genetic makeup of lacing on blue birds. I suspect that it has to do with recessive melanizers (sometimes referred to as recessive black).
I also think that the dark \'edging\' that Mike referred to above is the genetic component that we are looking for. We just need to select for a darker, wider edge. Bringing in the Blue Andalusian blood is a good choice for speeding up this process.
There you have it. The contrarian viewpoint.
Curtis