The genetics of bay, black and chestnut

Following on from this, do you know if the pattern genes have any statistical liklihood like the colours do eg if I bred my pure Haflinger (chestnut with flaxen mane/tail) to a strawberry roan or chestnut roan what might I get odds wise???
 
Black, bay or chestnut.

It depends on the exact genetics, but if both black and bay are hiding chestnut, you have a 25% chance of an orange baby. If neither have chestnut, or just one, you won't get chestnut.

Say neither has chestnut; if the bay has two copies of bay, baby will be bay. If the bay has only one copy of bay, you have a 50/50 chance of black or bay.
 
Heres a question for you chev, what determines the color of bay? My geldings dam was a gorgeous dark mahogany bay, and his sire is black w/a red gene(Sire's dam was dark bay as well). Jackson is a much lighter copper bay almost the color of a penny when freshly shed out, he does have some countershading but there is no dun in his lineage so I know it's not a "dorsal stripe" as w/Dun. Do both parents have something to do w/the color bay, or is it mainly just the parent that contributes the agouti gene?
 
The sooty gene contributes to dark bays, and can give quite a variation from vague countershading that resembles dun stripes through to those who have countershading all the way down the ribcage to the soft parts.

But as to what causes different shades... that question hasn't been answered yet!
 
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