When to count out recessive genes?

[miami13dol]

I have been breeding holland lops with (mostly) known gene sets for the A, D, and E genes which makes it fairly easy to manipulate. However, as all of my breeding stock has at least 1 dominant gene for both the B and C gene, when do you assume that they are homozygous dominant? Through all sets of offspring I have yet to see any chocolate (or chocoalte variation) and they all appear to have full saturation (C_). Is there a number of breedings that you would assume they do not carry the recessive genes for these traits or would you leave them unknown until they can be bred with another rabbit with known recessives?

 

[caroline]

you can't know until you breed with a known recessive. It can hide for many generations, especially if you don't have any [other] carriers that would show it up. Even when you breed with a known recessive it could take multiple litters for it to pop up. I've bred a black otter to a known chocolate carrier 4 times, for a total of 35 kits and it wasn't until her 6th litter that I bred her to another buck, also a known chocolate carrier and she had 1 chocolate kit out of a litter of 9.