By Leee on Tuesday, February 19, 2002 - 12:54 am:
Anonymous, Robbpa is referring to the anonymous post (very similar to your post here) that appeared on Feb 13 titled "Breeding Black to Self Blues".
I can't speak to the yellowing problem of the Belgian D'Anvers. As Rokimoto pointed out, the self-blue birds are usually homozygous for recessive lavender. Recessive lavender is different than the 'Andalusian-type' blue. BIrds that are blue because they are lavender homozygotes are referred to as "self-blue" because they breed true in the sense that you get blue birds when you breed two blue birds to each other. The blue of the Andalusian doesn't qualify as 'self-blue' because the blue birds are heterozygous (one gene for (incompletely) dominant blue, Bl). If you breed two blue Andalusians to each other you get 50% blues, 25% blue-splashed and 25% inherit no blue gene at all. The blue-splashed birds are the ones that inherit two blue, Bl, genes and are said to be homozygous for Bl. So these (Andalusian-type) blues don't 'breed true' like the Belgians that have recessive lavender do.
Some breeders of the Andalusian-type blue, Bl, will breed the blue-splashed homozygotes, Bl/Bl, to birds that have no blue at all, bl+ / bl+, so that all the chicks are heterozygous for blue. The advantage of this approach is that you don't have to kill or cull or otherwise dispose of any chicks and juveniles if the goal is to produce blue progeny.
The answer to your question about getting splash colors is: no, you shouldn't, since your Belgians should have lavender, lav, instead of Bl (Andalusian-type blue)