COLOR GENETICS! Testbreeding Using Ruby-eyed White: How, why, and when to do it by Kathryn M. Saria
In last month's issue of the HCRCBA newsletter, we touched on the basics of color genetics, including the basic rule not to breed shaded--represented as c(chl)--to agouti (A). Well, what if you have already made that mistake in your herd? What do you do then? Are you stuck with mottled color genetics and unpredictable litters, likely not to produce an entire litter of show quality animals... for life?
Nope. And here's why. I will begin by telling you my story.
I am a breeder of French Angora rabbits. I am very particular about choosing my breedings based not only on who I believe will compliment eachother body-wise, coat-wise, and in other ways applicable to my breed, but also breeding colors together that will not cause problems for my customers, or myself for that matter, down the line.
HOWEVER, I broke my own rule of having absolutely "clean" (compatible, following the color genetics rules to produce predictably show quality-colored litters) color genetics from start to finish in their pedigrees when I acquired a new fawn doe, Evangeline. Evangeline, a fawn French Angora doe, was offered to me from a breeder in Washington. One who did not speak color genetics, but who had produced some stunning offspring (which I had seen firsthand, here in California) from Evangline. So, what is the problem with Evangeline?
While Evangeline is show quality, and a lovely example of fawn color on a French Angora... she was produced by the breeding of two rabbits of incompatible colors: a "black pearl" (in most breeds, we refer to this as sable point, but in Angora, we call it by this name... yes, like the ship in the movie Pirates of the Caribbean--as a couple of exceptionally cute 4-H kids pointed out to me, when purchasing a buck from me bearing this color) and a fawn. What's the problem? Well... remember, one of the basic rules from last months article: DON'T breed SHADED to AGOUTI. While black pearl (or sable point) is a shaded color, fawn is an agouti color. Now, this is a bit of a tangent, but I feel the need to explain, as I have been asked this question before. If fawn is an agouti color, why is it listed in books under the category of "wideband"?
Here's the answer. While fawn is, indeed, a "wideband" color, the wideband colors are agouti colors. What makes them different from other agouti colors, such as chestnut or chocolate agouti, is the lack of the extention gene (remember, from last month's color genetics, big E means extention, little e means non-extension, referring to how far along the hair shaft the color is carried). In short, yes, fawn is an agouti color, and, if breeding true to the laws of color genetics, Evangeline's original breeder should not have chosen to mix a shaded and agouti color. BUT... here she is. And I needed fresh blood--purebred French Angora from another area, which can be difficult to find. Additionally, a friend owned Evangline's daughter, another fawn doe, and I have had the honor of carrying her doe to the show tables: amazing density, nice balance of guard hair, and awesome body. All those things we French Angora breeders are looking for. So, despite my rule to follow the color genetics laws within my herd, when Evangeline was offered to me, I accepted. Despite the unfortunate color genetics in her background, I do not regret it. And here's why:
Okay, here is Evangeline's true color using genetic code. Remember, she is a nice example of a fawn to all appearances, but that doesn't mean she isn't hiding other things that I should be aware of. Because of the previous owner's breedings, as well as my testbreeding with my grand champion ruby-eyed white buck, Frith (more on this soon), I know that, although Evangline is an agouti color, she carries shaded from her shaded parent. Evangeline's genotype: AaBbCc(chl)D-ee. I've highlighted the shaded gene she carries, because that is what can give us trouble with breeding.
So, what do you do when you have a doe (or buck) like this, with color genetics that aren't ideal, but whom you still want to use in your breeding program? In the case of Evangline, who carries shaded, you testbreed using ruby-eyed white, or REW. I will explain why in a minute. BUT... there is one very important fact you must keep in mind. REW can carry Agouti, but it can never (nope! Impossible! Goes against the laws of color genetics!) carry shaded. So, because I have many shadeds, and many REWs out of shadeds or self parents in my herd, I had no problem choosing a buck. I chose a buck with shaded in his ancestry, but NO agouti. REWs can carry agouti, and that will ruin your testbreeding, so make sure you are choosing a REW that is definitely aa, or a true self (not hiding agouti). I said in last month's article that a REW is like any colored rabbit wearing a white sheet. That's true. Just because they appear albino on the surface does not mean that they do not carry other colors.
So, in order to keep my lines "clean", I will breed Evangline to only non-agouti REW. I choose Frith, who I knew to be aa, and ended up with a litter that contained an interesting color mix of fawn, tort, pearl (a shaded color), and a couple of non-showable shaded agoutis (shaded colors with eye rings, having inherited both the shaded gene AND the agouti gene from Evangline, and were sold as wool animals to spinners with no interest in show... the problem in not breeding for proper color genetics). But, here's the good thing: my lines are clean, even using Evangline and her messy genetics within them. These babies can be used in my breeding program, and I will KNOW what their genotype is. If I would have bred Evangeline to any COLORED animal (anything but REW), containing a big C in the genetics (remember, REW is cc), I could ended up with beautiful agoutis (like Evangeline) who were hiding shaded! In that case, not only would I have the potential to really make a mess of the color genetics in my own herd, but if I ever sold one of her offspring bred to a colored animal (big C, not cc), I would be potentially passing on the problem to my customers... not part of my value system, thank you very much. With that said, Evangeline's original breeder simply didn't know any better. There are a lot of people out there who have not had the opportunity to learn these color genetics rules, and if you are one of them, don't feel badly. You are learning now!
Here's why it's safe to breed Evangeline to non-agouti cc (REW). The little c's can't hide her c(chl). So, if I end up with shadeds, I know they really are shadeds, so I can advise my customers (or myself) to breed to shadeds. If I end up with agoutis, I know they're really agoutis, not agoutis hiding c(chl), which can cause problems. So, even though Evangeline came to me with a background showing an interesting mix of color genetics, thanks to my non-agouti REW bucks, she can still be an asset to my breeding program. In fact, I have a fawn buck out of her that I am maintaining and quite excited about--and I don't have to worry about him hiding any incompatible colors, because he was bred to cc (REW). With that said, look very closely when dealing with a doe or buck with messy genetics like these. Look for eye circles on shadeds, white bellies, rings and other signs of agouti. I was extra careful when observing the colors of her litter develop, and paranoid as to shaded-agouti signs. If you have a doe or buck that you suspect MAY be carrying c(chl), because of their genetic background, but don't know for sure, testbreeding with non-agouti REW is also an excellent choice.
Hope this helped! Stay tuned for more color genetics tips next month!