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Building the Genotype of NZW-B

NZW-B is going to a new home in two to three weeks and I have bred him twice successfully. I cannot provide a pedigree on him but I can give his new owner what I know about his genotype, even if that is not really something that he will need if he only breeds New Zealand Whites as planned. However, plans change and now I wish I had kept more detailed records previously because I might have noticed some things far sooner and made different choices with breeding, but it was not our focus at the time. As I wrote, things change.

NZW-B is a New Zealand White, which means that he has hidden alleles, with the exception of the ones on the C-locus, until bred and the phenotypes (the colors seen) in the offspring provide information. This works best if the genotype of the partner is known also (but I just learned what one thinks she knows about genotypes of her older does might not be completely accurate even then).

This is the short answer about what I do know with certainty so far:

NZW-B is A_ __ cc DD __ enen

Now for the long answer...and I have put these in the order of most obvious or proven to least obvious and most unknown. When considering genotypes, it must be remembered that on each locus one allele comes from the father and the other from the mother. Also, the capitalized letter is the most dominate, while recessives are in small letters, and while all loci contain only two alleles, some have more than two possibilities, which have an order in dominance, but some alleles have co-dominance also.

C-Locus
I am starting with this locus because his phenotype is Red Eyed White and all REWs must have the double recessive "cc" on the C-locus. There is absolutely no guess work there. There are four to six, depending on who you read, possibilities on the C-locus but "c" is the most recessive. If this REW is bred with a rabbit not "carrying" white, that is not having a recessive "c," then none of the offspring will be the phenotype REW, but all the offspring will be white carriers in the genotype.

En-Locus
Another thing I know with certainty is he is not carrying the "En" broken gene, which can hide in REWs but not when bred with colored rabbits. It is so dominate that usually about half the offspring would be broken (spotted) and he did not throw any in two breedings. So, he should have the double recessive "enen."

D-Locus
There are only two possibilities on the D-locus: "D" for dense and "d" for dilute referring to the color. Dense colors are Black and Chocolate and dilutes are Blue, the dilution of Black, and Lilac, the dilution of Chocolate. NZW-B was bred with two different does: one Blue, who is a double dilute "dd," and the other was her daughter, who does not show dilute, but must carry it as she got it from her mother, so she is "Dd." None of his offspring presented in dilute colors, so NZW-B has to have a double dominate "DD" for dense. 

A-Locus
He definitely carries Agouti. "A" on the A-locus of the genotype. This is a picture of a Chestnut Agouti, one of his offspring when crossed with my Blue Silver Fox, Misty Blue, who is a Self "aa" and cannot be Agouti. Agouti is the most dominate on the A-locus, so if a rabbit has Agouti, it will show Agouti, unless it is hidden in a White, as in the case of NZW-B. 




In both breedings, he threw a Black Gold-Tipped Steel (GTS), which is also an Agouti rabbit or should have a dominate "A". 




The difference in between the Agouti Chestnut and the Black GTS is the pattern of the colors. The Agouti has white or cream inside the ears, and on the belly and tail, like a common cotton-tail wild rabbit.




The Black GTS has no cream or white on the fur, but a dark belly with black inside the ears. However, both have banded hairs that you can see when you either blow on the fur or part it.




Comparing the Chestnut with the Black GTS, they both have banding on the hair shaft where in places the black coloring is not covering the yellow base color of the hair, causing the golden tips in the fur. The overall effect makes both look brownish, but the Chestnut more so, yet both of these kits were born with black skin, not brown.

B-Locus
Although all of NZW-B's offspring have been versions of black and not chocolate, I cannot determine what is on the B-locus, because all the does have also only had versions of Black and no Chocolates. 

E-Locus
The E-locus the trickiest in this case because of the dominate Steel phenotype. Since Black GTSs showed up in both breedings, at least one parent in both breedings contributed Steel, but which? 

Steel is kind of a sneaky gene and will hide on an "aa" Self rabbit, only showing on an Agouti and a Tan-patterned. For Steel to show, it depends on the A-locus. I bred him with a Black GTS and a Blue (self) Silver Fox. I cannot say with absolute certainty that he is carrying Steel because I know one of the does has it and the other would hide if she did. However, I suspect NZW-B would have it because it is rather common for NZWs to have Steel and the albino coloring hides all the genetic color markers.

Still, the truth is there is not enough evidence to determine what is on the E-locus for NZW-B at this point.

The Possibility of  Super Steel
An "EsEs" Super Steel is basically a rabbit that looks like a solid Black, but is not actually an "aa" self colored rabbit. In both of his breedings, there were solid Blacks, one from an "Aa" Black GTS and the other from an "aa" Self Blue. If NZW-B carries an "a" Self allele, one to all of those solid Blacks could be Self Black. However, one to all of those solid Blacks could also be a Super Steel, where Black will cover the yellow banding on any Agouti.

My Silver Fox Blue doe is a Self rabbit and Steel can be carried on a Self, yet not seen. After the surprise of finding she carries Chinchilla, I suspect her geneotype much more than I would like. Her daughter, the Black Gold-Tipped Steel, obviously carries Steel, and likewise she could have it from her mother or her NZW father. 

So, it is as likely that the solid Black offspring are Super Steels as it is that they are Self Blacks and for that reason, I cannot fill in the E-locus with any certainty at all, therefore it remains completely blank. Test breeding would have to be with a doe that is known not to have Steel to prove or disprove Steel in NZW-B. If it was proven he did not have it, then none of his Black offspring could possibly be Super Steel Blacks.

So, for now we know that NZW-B is an Agouti that would have been born with Black skin if he did not have the albino alleles.