Since getting Opals from another breeder, I have been continuously improving them by outcrossing them to my line of Cream Legbars. The only consequential difference between the two is the gene called lavender. This gene is common in many breeds of poultry, resulting in color variants called Lavender, Self-blue, Isabel or Isabella. Isabel is the technical name for the Opal Legbars, and consists of the Lavender gene added to a wild-type pattern. This is most well known in the Isabel Leghorns, which were used to create Opal Legbars from a cross to Cream Legbars.
There are several additional genes at play with the Opals in addition to the Isabel color:
- Blue egg gene (O) – single gene dominant, autosomal
- Crested gene – single gene, partially dominant, autosomal
- Sexlinked Barring – single gene, partially dominant, sexlinked (responsible for autosexing)
- Cream – single gene, partially dominant, autosomal (hard to detect when combined with lavender)
All these genes make for a rather complex process to create the Opals. All of these are correctly homozygous in a good line of Cream Legbars. There is some debate about the usefulness of the cream gene when combined with lavender. I tend to ignore the cream gene, but assume that my line is probably homozygous for cream or heading in that direction. Outcrossing to this good line of creams, will bring the Opals closer to the proper homozygous state for all the genes. It is useful that most of the genes are partially dominant, so you can tell if an individual is heterozygous or homozygous. With the blue egg gene is much harder to detect the genotype, but there is a genetic test for this that is readily available (IQ Genetics in Miami, FL).
Outcross Options
- Opal male x Cream females – This is the pairing I use because it is so simple to add some Cream pullets to the Opal breeding pen. All chicks that hatch as not Opals (normal color for legbar chicks) are the chicks from the Cream pullets. They are kept as F1’s of the outcross.
- Cream male x Opal females – You can use this pairing, but do not keep any cream females in this pen or you will not be able to differentiate between the F1’s and pure Creams.
F1 pairings
- F1 x F1 – Sibling pairing of the F1’s results in F2 chicks that are 50% genes from the Cream Legbar parent. Do not be concerned about this as inbreeding, these are very far from being inbred. You can inbreed these for many generations before you see any inbreeding depression. These F2 chicks will be about 25% Isabel and 75% Cream phenotypes. The creams are not reliably heterozygous for the lavender gene, but are excellent layers, so typically easy to sell if they are female. You can tell both the sex and the chicks that are homozygous for the lavender gene at hatch. This is a great help in knowing which chicks you should keep.
- F1 x Opal – Pairing the F1’s to a pure Opal will result in F2 chicks that are only 25% Cream Legbar genes, but you should get about twice as many of the Opal chicks. About half are true Opals, the other half are more heterozygotes (like the F1 chicks).
My process for outcrossing Opal Legbars
- 2023 – Tested Opals for the blue egg gene, selected only O/O breeders
- 2023 – Added pure Cream Legbar pullets to the O/O breeder pen
- 2024 – F1 x F1 of chicks hatched from those Cream Legbar pullets, kept only Opal chicks
- 2025 – Opals (now 50% CL genes) as breeding flock. Added pure CL pullets. Keeping heterozygous chicks as breeders.