I wanted to share the results of my first look at these chicks. There are 40.
From my slow lav cock (the pen B male from 2011) crossed on a lav pullet I have 9 lav chicks with no tails. Whether there are any stubs in the tails, I will have to look again later, but I think we definately have K going on with those.
From my slow lav cock (same guy) crossed on a split pullet I have 2 lav and 5 splits, all with no tails. I will look for stubs in the tails at a later date. More K, I believe.
From my lav cockerel in pen B (picture follows)
crossed on two splits (daughters of Smith black hens that were bred to the slow lav cock), I got 12 lav chicks and 4 of those are fast feather, with 1\" of tail growth today at around day 10-12 (this batch of chicks took 3 days to hatch). I also got 12 splits and one of those is a fast feather with 1\" of tail growth. Now, I did not start looking at this until midway through the chicks, and I will go back and look more closely later, but on the chicks with no tail from this group, I did see about 1/8\" of tail feather stubs poking through. I am hoping these are fast feather males. I compared to those sired by the slow cock and they have no stubble, only down is present on the tail.
So I say with some reservation that I think I have a lav cockerel to work with in order to eliminate K in my flock.
As an aside, I did notice that some have obviously wider feathers in the wing primaries than others, so culling for narrow feathers can probably done at this age, also.