1. There are 2 blues and they are very different genetically, but only slightly different in appearance. You can easily find pic of BBS (Black/Blue/Splash) blue Ams, and of course you know what the lavender, aka "self-blue", look like. The word picture I use for lavender is "brushed aluminum". The soft grayish blue color is very uniform. For the other blue (BBS), I think of "blue lace", because the color is not uniform if you look closely. Individual feathers may have darker edging. I don't think that is true of the lavenders.
2. It is highly unlikely that you will get any lavender chicks. That would require that the hen was "split for lavender". Since lavender is fairly new and somewhat rare in Ams, I'd say the chance of this is near zero. That said, every blue chick you now have, is this exact combination, so it is possible if the hen had a lavender ancestor (as all of yours do). What you see as a blue chick is showing BBS blue. Here's why:
It may be hard to believe, but every lavender, blue, splash and black chicken is genetically black (called "extended black"). This EB gene is very dominant over every other color (except dominant white, like commercial leghorns). So the lavender roo passed a dominant EB gene to all his progeny, making every one have at least EB gene and making the base color black for all of them, even the chicks from the EE hens. That is why the chicks from the EE hens look so much like the ones from the blue hen, daddy gene trumped everything and those chicks are all very black!
Except for the ones that got the BBS gene from their mom. About half of her chicks got that gene because genetically a blue bird (BBS blue here) is not "pure" for that gene. They are heterozygous if they are blue, if they have 2 copies of that gene, they look splash, and if they have no copied they are black. Remember that the cock, though lavender, is a black bird as far as the BBS gene is concerned, he has no copies of that, so he can't make a blue chick, only the hen can make a chick blue in this scenario.
So, for your chicks from the blue hen, this is how they look, and the genetics they are carrying:
Black chick - 1 copy of the lavender gene (recessive, so it's hiding), no copies of the BBS gene
Blue chick - 1 copy of the lavender gene (recessive, so it's hiding), 1 copy of the BBS gene (dilutes the black to blue)
3. Lavenders will always breed true. Breeders often cross to black because the lavender genes seem to weaken the birds when inbred, but that's not to keep the color, just prevent inbreeding weakness. Blacks and Splash colors also breed true. It's only the BBS blue birds that don't produce all blue progeny, and that's because they are not homozygous for the BBS gene.
The "recipe" to create a strain of true breeding Lavender Ams from your chicks is really quite simple. Take a black hen from the chicks you just hatched and mate her with either her father (or any pure lavender Am) or a black brother. This should produce either 50% (lavender roo) or 25% (black roo that has 1 lavender gene) lavender chicks. I bet that is what Troyer is planning to do.
Using the blue chicks will do the same thing, but the presence of the BBS gene will make it harder to determine which of the progeny will be true breeding lavender. You might be able to tell by their coloring, but I'm not certain how they will look if they express both types of blue at the same time.
I can see why people would not try to inbreed the lavender gene. Well, unless I can find a non-crowing lavender roo (don't want to bug the neighbors), or maybe borrow someone's next year for a just a few weeks in the late springtime, I don't think that I'll be starting a breeding program any time soon. Keep me in mind, though, if you see a way to start a mid-PA lavender Americauna breeding program that would involve my hens! I'm happy to raise on a small scale. I'm sure the more diversity, the better with breeding birds.
