02/03/2024
Information Regarding Recessive Chocolate
Article by Christina M. Cain (Nevermore Rodentry).
If you would like to post the information on this article, you are welcome to, but please give proper credit.
If you would like your Rattery added to known breeders with this variety, please contact me. If you would like to contribute to the article or photos, I would love that. You will be given full credit.
Genetics: b/b (b-locus)
Black Pigment (eumelanin) is diluted to brown. Yellow and Red pigmentation is unaffected.
General Standard: Chocolate (a/a b/b) - To be a rich, warm Chocolate Brown color, devoid of rusting, discoloration or molting patches. Avoid Silvering. Aim towards breeding this variety in self. The topline color should match the ventral area and be as evenly colored as possible. Eyes Black. Skin, Tail and Ears should be brown.
Chocolate Agouti (A/- b/b) - Chocolate Agouti is a rich warm reddish brown, ticked in Chocolate brown fur. The base of the coat is to be slate grey. Chocolate Agouti is quite distinct from Agouti when compared to each other. Next to Cinnamon, Chocolate Agouti takes on the appearance of Agouti, as Cinnamon is a much richer shade than Chocolate Agouti.
Additional Information: Recessive Chocolate is exceedingly rare in the United States. We simply do not have it circulating in the pet fancy. In over two decades of breeding, I have only randomly encountered it twice. I have worked with five different lines of Chocolate and three of those were given to me as proven lines. If you think you have Chocolate, you probably do not. I'm not saying this to discourage you from testing out your lines, but I think it is very important to have realistic expectations. That said, some lines do indeed test out. So, if you have the room, time and patience, by all means, test breed and attempt to find out. I will include information below on identifying Chocolate and test breeding to find out if you have Chocolate.
Breeding Goals: Most lines of Chocolates do not start out a rich warm brown and might appear as a slightly off brown that resembles a bad black. Does this mean every bad black is a Chocolate? No, most certainly not. But once you've proven your line to be recessive Chocolate, selective breeding can begin to breed towards the proper shade of brown, if this is your desire.
Sometimes, it's simply a matter of selective breeding. Set a goal for the warmer and lighter animals and continue to slowly work towards these goals.
Other times, a decent out cross will assist you in achieving your goal a touch quicker. When out crossing Chocolate to achieve a warmer brown, I would recommend one of two out crosses. One, out cross to a RED. This seems to lighten and assist you with warmth.
The secondary out cross would be to rich, warm Agoutis with excessive reds in their banding. Stay away from Agoutis that are cool in shade, with excessive yellows. The goal isn't to breed the Agouti to standard, but to bring in the warmth from them and the possible modifier that is causing it. While this doesn't get you to where you need to be immediately, it does seem to warm and lighten the brown slightly. The goal is to remove the coolness out of the line you are working with and bring in warmth and a warm Agouti has always been a way to accomplish this, in my opinion.
When trying to brighten Cinnamons and add warmth to Mink, both of these methods seem to be effective.
Identifying the Gene -
Tim Tam or Dominant Chocolate: There are Chocolates in the US that are dominant. We imported them with Australian Mink and they are called Dominant Chocolate or Tim Tam. If you breed your Chocolate to an unrelated rat and continuously produce Chocolate, you are likely working with Tim Tam or Dominant Chocolate. They can look extremely similar to Recessive Chocolate, with a warm brown coloration and rich colors. They generally have interesting molting patterns, unlike Recessive Chocolate.
Silvermane Diluting Black to Chocolate: Silvermane has the ability to dilute Black to a brown Chocolate color. They can be quite convincing to the untrained eye, but again, the inheritance will be dominant. Breeding them to another unrelated rat will sometimes produce more. A key visual difference is while they are very Chocolatey in tone, they are also very cool colored.
c-diluted Black: There is no visual difference between Recessive Chocolate and an excellent c-diluted Black. I've made more attractive c-diluted Blacks that I have Chocolate. They are rich and warm in coloration. That said, they are generally extremely hard to reproduce and with age, they tend to cool in shade quite a bit. Inheritance is extremely spotty and doesn't seem to pass dominantly or recessive in nature. They are random within a c-locus line. I have hypothesized that there is perhaps a modifier at play.
Bad Black: Offspring are born with black skin and black eyes. Generally speaking, they do not reproduce themselves. While they might mimic the darker, cooler Chocolates, the will not breed true. Skin black, ears, tail, feet and eyes black. Prone to patchiness.
Snowflake: Snowflake is prone to dilute black to a rich reddish brown coloration. They are generally quite splotchy and rather than a warm brown, they are a slightly reddish brown. Inheritance is tricky as Snowflake is capable in the first generation of diluting black to brown, it can also take a few generations to do so. Most likely, if your browns originate from a Snowflake line, I would highly suspect the Snowflake gene is at play. To test breed, I would approach them by breeding two of the browns together. If you get an entire litter of browns, I would attempt further testing. Inheritance doesn't seem to be recessive with the diluted browns in Snowflake lines.
American Mink: A warm American Mink can be deceiving. They can match phenotype relatively well, inheritance will be Recessive. Visual differences are subtle, but skin is much lighter as kits with American Mink than Chocolate and eyes are often a very dark ruby. Kits will develop their pigmentation a few days after black kits. Use a flash light to shine kits to see the difference in black eyes vs. very dark ruby.
Recessive Chocolate: Eyes Black, coloration of tail, skin, ears will be a light brown. Skin color should be virtually black, with a slight shade different. Next to a black kit, it should be barely noticeable. Kits will develop skin pigmentation generally one day slower than black siblings. Eyes should be as black as a black kit's eyes. This will assist you in identification with kits. Inheritance is Recessive. Coloration can be cool and brown to warm, rich and brown, depending on the line. Chocolate is extremely variable in expression.
Test Breeding:
Check the inheritance of the gene you are working with to eliminate dominant genes from the list of possibilities.
Test breed against other browns you know the genotype of. If you have American Mink or UK Mink, test breed against them.
Out cross to self black lines to assure it is not dominance in nature.
I will include a link to known breeders with Recessive Chocolate. Contact one in your area and see if they will test breed for you once you have gone through the rest of the steps.
Different Varieties of Chocolate -
A/- b/b - Chocolate Agouti (Chocolate + Agouti)
a/a d/d b/b - Russian Chocolate (Russian Blue + Chocolate)
a/a m/m b/b or a/a mo/mo b/b - Cocoa (Chocolate + Mink or American Mink)
a/a g/g b/b - Classic Lilac (Chocolate + American Blue)
Breeders with Known Lines of Chocolate -
https://www.facebook.com/nevermorerodentry
https://www.facebook.com/jaawillamettevalleyrattery
https://www.facebook.com/CosmicBlissRats
https://www.facebook.com/KaiZenRodentry
Additional Resources -
https://ratvarietyguide.weebly.com/chocolate--sienna.html
https://www.afrma.org/c-c_chocrats.htm
https://www.nfrs.org/articles_self.html
Album Link: https://www.facebook.com/media/set/?vanity=nevermorerodentry&set=a.892815672637657
