Also, testing a horse for Agouti does not tell you whether it is A+, A, or At. It's not always obvious, because a horse with A/At will appear as a bay horse, but you don't know he can produce brown (or nearly black). There is also debate as to whether brown is actually entirely caused at the A locus, or whether there are other factors in play. Since Pet DNA services keeps the test procedure secret - nobody knows how they test for brown, except them. There are a lot of black horses in brown lines. If you study pedigrees, this becomes apparent very quickly. Look at the Morgan breed, too - where browns, livers and blacks are more prevalent (probably descended from Welsh Cob).
This brown stallion, (At a E e) was registered as a bay. But his 'a' gene came from a liver chestnut horse - so he only gave liver and brown. 90% of his foals were darker than his red mares 10% were the same red shade as his mares, and zero foals were lighter than his mares. There's so much we don't know about how Agouti series may affect the shade of red - and what effect the presence of other unknown modifiers might have.
What? A great horse can ABSOLUTELY
... also be a wonderful color!
Last edited by LilacsGirl; 07-18-2010 at 06:59 PM.