So may I ask then, why an animal that is homozygous for caramel not good enough?
Why must he breed to a straight Caramel het for nothing? Is that really as easy to find as you think? And why would the results be different? How could they be different, it is still 100 percent CARAMEL gene, wether is a an Amber, or Golddust, or Butter.
I'm arguing the point about it doesn't matter what Caramel something you use. When something is homo for Caramel, you can use that animal to test for the Caramel gene!
A butter corn would have a TWO caramel genes the exact same as a straight Caramel would at that locus. As would a Golddust, or Amber, or Topaz... As long as the animal you are using is homozygous Caramel, it can be used to test for Caramel.
If I have an animal that is suspected to even just CARRY the Caramel gene, and all I had was a BUTTER corn, I'd still get all normal babies if he didn't carry the Caramel gene. And if he did carry, half the babies would be caramel since the butter is 100 percent Caramel.
So I ask you, why are you insisting it must be only Caramel and nothing else to be able to test for Caramel?