The genetics are an interesting and evolving subtext to phenotype. To quote Walt Leonard, APA Standards Committee and APA judge, “The birds … only need to look like the description given to the APA. The APA does not care what genes they are carrying as long as they reproduce 50% correct … with the normal variations that any color pattern would have.”
U.S.A. Legbars are all understood to be gold-based birds: the Cream Legbar, the Golden Crele Legbar and the White Legbar. The genetic variations differentiate the colors and patterns. For example, the Golden Crele is essentially the base color and pattern for all three varieties.
The Cream Legbar has the identical body type, base color and patterns as the Golden Crele, but it is a variation on that theme, modified by two copies of the gold inhibitor gene (ig/ig) also known as the cream gene. Learn how the cream gene changes the gold body color, the barring pattern, and other feather colors. You can find the genetic formula for the Cream Legbar on page 17 of the breed guide. Page 18 contains a discussion on genetics.
The White Legbar is also identical to the Golden Crele Legbar and the Cream Legbar. It is understood to be a gold-based bird which has barring genes, and may or may not have the cream gene. The White Legbar does have two copies of the recessive white gene (c,c) which masks or prevents the expression of color and pattern.
You may enjoy these genetic discussions:
- Chicken Basics
- Genetics for Exhibition Breeders
- Poultry Genetics for Small and Backyard Flocks