I don't have an explanation for you but I can tell you that this is precisely what my problem earlier this year was with every single genetic blue I produced.
I had four pairs involved in the losses, but there were genetic links between all of them.
I had a single pair produce somewhere between 8-10 blue hens and I lost every single one except maybe ONE, which was given to a friend of mine in NJ. This thread actually reminded me to email her and see if she ever molted and if she's doing well.
I lost all four silvers I produced between two different pairs, and out of the 6-8 pastels (1 from one pair, the rest from a second) I only have two left.
One has finished molting and seems to be healthy, and the other appears healthy as well and is currently molting.
I have to believe it was something genetic with the four pairs in question that produced these birds.
With the Silvers I lost - it was a Brother/Sister combo I had purchased in 2009 paired to birds of my own, one of which, Saki, had produced 6 enormous healthy Silvers in 09 so I know the issue can't be with her.. and since his sister was paired to Saki's son and I lost THOSE silvers, too, I have to think there was something wonky in the purchased line of birds.
With the other two pairs, Bella and Mystic and Rachel and Astley..
Rachel and Mystic came from the same breeder in Texas, and I had nothing but problems with the offspring from both pairs. And it didn't matter WHO raised the offspring, because I tried everything under the freakin sun to try to get these babies to survive:
1. My friend Carol had her societies raise four babies in her home from EGGs, the only blue produced died before molting.
2. I had two other PROVEN pairs incubate and raise babies, in one case, along side their OWN eggs - the eggs from Rachel/Astley, I lost two out of the four offspring but all of the original parents babies were fine
3. I had MY societies raise babies and still lost all of the blues or silvers
It doesn't make any sense unless the birds are just genetically weak.
If it was disease related, why wouldn't other pairs be having similar problems?
Cut to this fall - I paired together one of the surviving Dilute/Blue males from Bella and Mystic with a Normal/Blue hen from an unrelated pair.
I have two blues, a pastel and a silver from them so far and SO FAR I haven't lost anyone.
At this point in the game before, they typically would have died already (like with you, shortly after or even before weaning). They would just start to fail to thrive and die.
I wish I had some answers - but I wonder if you selected different mates if you might be more successful.
I will say in the case of Bella/Mystic, literally all of the birds I lost were predominantly female, and this was a RH hen x BH male pairing, which according to Dr. Prykes research is incompatible and results in high female mortality....
Hope you can get it figured out...I can't offer much insight but I would think that it is something genetic for sure since the other colored siblings fare well.
