I was browsing the AFRMA standards pages looking at Cream and Ivory, and was wondering if you would mind explaining the difference to me. I just don’t understand the difference between the two.

A BEW can’t be c^ec^e in the normal sense as c^ec^e is usually very dark (what England calls Stone/our Reverse Siamese or our Coffee; Beige is also c^ec^e but a lighter shade; it’s just a dark version of Ivory) unless it is on dominant yellow or recessive yellow (ee c^ec^e). If it is not on

An Ivory (cec) owned by and photo by Karen Robbins.

dominant/recessive yellow, it would be c^ec selected for whiteness. In the photos you sent of a Bone and a BEW, they look the same, so based on the usual genetics of this color, they are both the same but selected for more white for the BEW. When you breed c^ec^e to cc you get all c^ec. Most clubs just use c^ec on chocolate (Ivory/Bone) selected for very light/white for this version of BEW. England’s B.E. Cream/our Ivory is c^ec on a Chocolate background. You can get it on a Black background—I have one recent male that was Bb as he produced Black and Chocolate when bred with Champagne [he went back to my cross of old PEW English that was genetically Lilac (P.E. Black aa pp) with the new English B.E. Cream bb]. The problem with using c^ec for BEW is they tend to get darker/watermarks and won’t stay “white.” You could get BEW by c^ec with agouti plus black (A– B– c^ec) and they would still have the off white problem but wouldn’t get fat. BEW is usually either Marked with all markings bred off, from Variegated, c^ec^e on dominant yellow, c^ec^e on recessive yellow, or very light Ivory/B.E. Cream/Bone c^ec. Genetically when you breed Ivory/Bone/B.E. Cream with PEW you get Ivory and PEW. The only way you could get Bone/Ivory from Silver Agouti is if the Silver Agouti were carrying other things.

I asked Nichole Royer (our genetics expert) for more details as I have never done a Silver Agouti to Ivory breeding and this is what she says about breeding Silver Agouti to Ivory and about BEW: “Recessive yellow eliminates all the black pigment from the coat and leaves just yellow pigment behind. c^ec^e eliminates all yellow pigment. So together that should give a BEW. I’ve never tried it, but logically that’s how it should work.

“Breeding Silver Agouti to Ivory would get some Agouti babies; however, if the Silver Agouti was actually Aa or Aa^t then it’s entirely possible to end up with Ivory/Bone. Silver Agouti could easily be Aa, and c^ch plus any of the alleles lower on the C locus will strip away yellow pigment (and dilute out the black slightly). Well, I should say any of the alleles other than c^h. Chinchilla with the white belly is Aa^t. Also, to truly get a really good Chinchilla you logically would aim for ‘c^chc^e’ or ‘c^chc.’ c^ch will leave the black pigments fairly dark, but carrying alleles lower down on the locus the red/yellow pigments even more than c^chc^ch. Thus, if you don’t assume the Chinchilla is AA c^chc^ch, but instead is carrying other things, then it is possible to get Ivory/bone. It’s not the combination I would breed ‘expecting’ to get Ivory/Bone unless you knew that your population of Chins happen to have been bred for that background.”

On your question on Cream vs. Ivory: Cream is for the Chinchilliated Fawn A^y– c^chc^ch or Chinchilliated Red A^y– bb c^chc^ch and that is what we had been showing prior to getting the English B.E. Cream, where the Ivory is for the “Beige” family c^ec (when these mice get “watermarks” or have moult marks, they can be streaked/blotched with Beige on them). England kept one standard and just changed what they show for that color—for the last many years it has been the c^ec mice, but in the beginning it was the Chinchilliated Fawn/Red.

AFRMA’s Mouse Genetics book would be useful for you to have if you haven’t gotten a copy yet.

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