NZW and Silver Fox Cross - Black Agouti!

[Seeker]

Hi, I am new here. I just had to share this and ask if this has happened to others:

We have been crossing New Zealand Whites and Silver Foxes for about a year. Our SF buck is black and has consistently thrown black and blues whether breed with our SF Blue or our NZWs. This last kindle, we got two black broken, two blue broken, two blues, and two blacks...so I thought, but one of the blacks looks like a black agouti! I am not sure if this one has the NZ roll back fur or the SF fur, but what a surprise to get the agouti look when we only have solids and steel tipped--actually that probably should read silvers.

 

[Bunnylady]

You aren't confusing the silvering of the Silver Fox with Steel, are you? Steel and Silver are two entirely different genes, and the reason I ask, is because a lot of NZ's carry Steel. Two copies of Steel results in a rabbit that is solid colored, like a Self, even if it has two Agouti-pattern genes. When you breed such a rabbit to one that doesn't have Steel, you get babies with only copy of the Steel gene and one normal gene, which can result in Agouti-patterned babies coming from two apparently self-colored rabbits. A rabbit that is a visual Steel (showing the dark, ticked, Agouti-patterned coloring called Steel) can only have one copy of the Steel gene (because rabbits with two copies look like Selfs). Some Steels are very dark, and may just have a little bit of ticking, which to some degree may resemble the scattered white hairs of the Silver. But if you breed a visual Steel to a rabbit that has at least one copy of something other than Steel, you can get babies that have no copies of Steel, like a Chestnut Agouti.

I refer to Ruby-eyed White as "the light switch," because you really can't tell what sort of genes a REW is carrying (other than two copies of REW) just by looking at them. Sometimes their pedigrees will give you a clue, but often, it's only by seeing what they produce that you'll really know. Obviously, at least one of your NZW's is carrying Broken . . . . aren't genetics fun!

 

[Hens and Roos]

Welcome , post some pictures when you can- it would be neat to see the colors! We are still learning genetics with our rabbits!

 

[Seeker]

I admit not knowing much about the variations in colors because we only had NZW for several years. The kindle is way too young to know if they are silvering yet, but this one has more of a blue underside so it may be more of a steel. I just don't know, that is why I am here! Here's a pic:

 

[Hens and Roos]

Neat coloring, hopefully someone will give you an answer as to the coloring.

 

[Bunnylady]

Seeker, that baby looks like a gold-tipped Steel.

This is a picture of a Gold-tipped Steel that someone posted here (sorry, I don't remember who it was, if this is your image, I hope you don't mind me borrowing it, whoever you are ). If I remember correctly, both of this rabbit's parents were New Zealands, they just were different colors:

A typical Steel looks a lot like a Chestnut, the biggest difference being that there is a lot more black in the coat; even the belly and underside of the tail frequently wind up dark.

 

[Seeker]

Thank you. It looks like you have identified it. Still shaking my head how we got anything showing Chestnut! I guess I have lots of learning to do when it comes to genetics.

 

[Seeker]

Okay, one more question. I have been reading information about the genotypes. Several places state that for the ticking to show the A series genotype has to be Agouti (A_) and a few other places on the Internet state it can be self (aa). Since REW can hide so much of their genotype, I am confused and the kit does not have a light underside as I believe is the Agouti color--in fact, we have not seen that at all in any of the breeding we have done in the past year. So what would be the genotype of my black gold tipped steel, assuming that is the correct description?

 

[Bunnylady]

Genotype of a gold-tipped black Steel:
A_B_C_D_EsE

I can't imagine why anyone would think you could see Steel ticking on a rabbit that has self in the A series (aa). That makes no sense at all to me.

Look at it this way:

Every rabbit has the potential to produce 2 pigments, a black/brown pigment (Eumelanin) and a yellow/red pigment (Pheomelanin). There are a bunch of genes that determine how much of each pigment a rabbit produces, and just where those pigments show up.

Unless a self-patterned rabbit (aa) has other genes that say otherwise, it has both black and yellow pigments in its hair, you just can't see the yellow because the black that runs unrestricted all through the hair shaft is covering it all up. The Agouti gene (A) restricts the black pigment to certain areas, which allows the yellow pigment to be seen in the areas where the black isn't.

Steel happens in the Extension (E) series. When the people who first worked all of this out did so, they assumed that normal extension would be the most dominant gene in the series, so they gave it the upper-case E. Then they discovered Steel, which turns out to be dominant to normal extension, so the E series has two capital E's, normal extension (E) and steel (Es).

On a typical Agouti-patterned rabbit (in this case, Chestnut), the body hairs have a black tip, a yellow band in the middle, and a dark gray base. The black tip "extends" the normal distance from the tip down the hair shaft. On a Steel, the black tip gets extended further, which makes the yellow band much narrower, and the whole effect is a darker, blacker coat, with just gold ticking rather than the gold-and-black sort of salt-and-pepper blending that results in the typical wild-type Chestnut color. Steel frequently causes extra black pigment to appear in other areas where an Agouti-patterned animal normally would be light-colored, like the belly and the underside of the tail.

Since the Steel gene causes the black tip to extend further than normal, Steel on a self-patterned rabbit has no visible effect at all. I mean, extending a black tip down a hair shaft that is solid black anyway looks like what, exactly?

The crazy thing about Steel, is that how it looks depends on what it is paired with in the E series. If a rabbit inherits Steel from both of its parents (EsEs), it will be solid black, looking exactly like a self (aa), even if it actually has Agouti genes (AA). I have seen Steel do this when paired with non-extension (e) and harlequin (ej), too. I bred a NZW to a pedigreed Harlequin, and got 100% solid black babies. All of the offspring inherited an Agouti gene from their Harlequin father, but the Esej combination made them solid black. I have seen a little bit of ticking on rabbits that were Esej or Ese, but to get the look of a classic Steel, you must have one copy of Steel, and one of normal extension (EsE).

 

[Seeker]

Thank you, Bunnylady, for taking the time to explain it all with so much detail. I am beginning to understand more about how each series works in combination. I am sorry to keep bothering you, but I trying to zero in on the genotypes of the REW we have. I know that no matter which way I cross the three of them with our Silver Foxes, NZW doe or buck, I am getting brokens (Enen) therefore all of them are carrying the series that controls that. So would you put that as just En_ for the REWs?

While on that subject, is it possible for an REW to carry both En and Es or could the SF carry the steel and not show it? From the things I was reading it is such a tricky series so I understand why this is the first time we have seen it. We have nothing on the NZW but we have a pedigree on the SF sire and as far as we know his genotype looks like this aa B_ C_ Dd E_ sisi.