Steel Rabbit Genetics

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First the Facts: The 'Es' gene results in the undercolor extending all the way up the hair shaft, wiping out the ring, and eliminating the white belly on an agouti. Steels can come in black, blue, chocolate or lilac, and either gold-tipped or silver-tipped.

Agoutis that express their yellow pigment (castors, chestnut agoutis, etc.) turn into gold-tipped steels in the presence of a single Es gene.

Agoutis with yellow pigment suppressed will become silver-tipped steels.

The rabbit pictured below is (I think!) a black tortoise holland lop, however it exhibits steel rabbit genetics. The steel gene completely changes the appearance of the rabbit. It now falls into the category of a gold tipped black steel.

Double the ‘Es’ gene (EsEs), and, depending on the modifiers, you may get a rabbit that is virtually black--so dark as to overpower even the tipping. But, we suspect you might be able to find a clue somewhere in its fur...some snippets of color...that the rabbit may not be a simple black rabbit.

An ‘EsEs’ with very few darkening modifiers might simply be a very dark steel.

Because of its nature, the Es gene can play sneaky tricks on the breeder.

The 'Es' steel gene appears to have the ability to hide, to sneak around the gene pool and crop up here and there as if on a lark. And since the 'Es' gene is frequently described as being dominant, more than one expert rabbit breeder has been shocked senseless to discover steel rabbit genetics in the nest box.

There IS a very logical explanation for the sneaky ‘Es’ steel gene.

This rabbit is a white-tipped black steel Mini Lop.

By definition, a dominant gene shouldn't ever be able to 'hide.' So by its behavior, the ‘Es’ gene is most likely incompletely 'dominant.' It appears to be dominant only because its effect is usually overpowering.

What we think happens is this: The ‘Es’ performs its role while still allowing the other half of the locus to also perform its role. Geneticists call this incomplete dominance. (See ‘C’ Rabbit Colors for more examples of incomplete dominance.)

What happens when you put opposites -- 'Es' and 'e' -- into the same rabbit? If ‘Es’ were completely dominant, you'd see a steeled rabbit. Instead, in the animal with ‘Ese,’ the 'Es' will extend the black, and then the 'e' will wipe it out, because that is what 'e' does. The ‘Es’ still allows the 'e' to perform its role, and the end result is the 'e' canceling out the effect of the 'Es.' What you SEE in real life is something resembling a normal-colored rabbit!

This is how an animal you coulda sworn was a normal, run-of-the-mill chestnut agouti, suddenly has a steel baby. It was ‘Ese’ genetically, not ‘EE.’ Pretty crazy.

The 'Es' gene can affect selfs and tans as well. The pedigree might help you track down where the steel came from, when you start getting big surprises in the litter box.

If you wish to eliminate the ‘Es’ gene in your rabbits, the surest method is to test-breed to an ‘ee’ rabbit. We know that the dominating steel gene can 'hide' and play tricks, but there's for sure no steel gene in a non-extension ‘ee’ rabbit. By observing the genetic makeup of the offspring, you can determine the identity of the E locus genes, and use only those animals that do not carry a steel gene.

Just know that any first generation (F1) offspring that "look" normal ‘EE’ agouti might actually be ‘Ese’ hidden steels. Continued breeding will identify the underlying genes, and you can keep the animals that no longer carry an ‘Es.’

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Here are some other links you may enjoy:

• Rabbit Care

• Plush Rabbit Toys

• Conditioning Rabbits for Show

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