A friend of mine has a Grulla colored mare. We were both curious because compared to another Grulla at out stables, the two look totally different! Is there different color types for Grulla or are all the variations just call Grulla?
All grullas are grullas. People can make up all the shade variations they want and call them different thing but in the end theyre all just Grullas. My best friend and I both have red roans. Her's is more roan and looks absolutely pink with a coontail and flaxen mane. Mine looks almost tan. Not as much roan, base color isnt as bright. Mine's tail is sorrel and her mane is almost flaxen. We both consider them red roans. Because that's what they are reguardless of the shades or amounts of their colors.
Yep, all grullas are genetically the same (for the genes we know about so far). They just express differently in individual horses. You see the same thing in a lot of different colors- chestnut/sorrel horses, for example, can be anything from a bright coppery red
While a grulla is a grulla is a grulla, their colors can range from an olive-ish looking color to a slate color. My girl has been called a blue grulla (see my avatar) because she is a slate color. She is still just another grulla, though.
A grulla is a black dun- black with dun gene. Any base coat color can have the dun gene, and as with any base color, there are lots of different shades, brightnesses, and can be other 'modifiers' like flaxen or sooty. It also may depend on your horses diet- do they get a lot of oil and fatty food? Or sun exposure- do they spend most of their time indoors or in a stall? Are they a rich, dark color, or are they slightly dull and sun bleached.
They can vary from light to dark, but genetically they are all grullas, and they are going to have certain characteristics that are same. That said I've seen plenty of sooty buckskins and grays that people called grulla.
(my favorite is "well he was buckskin, but he's turned grulla")
That's due to Lp going all "funkify" on her coat though, nothing to do with being grulla. Well, except that Lp loves to funk with black bases most of all.
In terms of colour variation, there are a few reasons for the huge variety in grulla. First, is the natural tendency for horses to have coats that have an "individual" shade even if they are genetically the same. These two mares are clones, so share identical DNA. Yet even then, you can see some variety in the expression of colour, with dark areas being more extensive in some areas etc.
Another reason shade can vary so much from horse to horse is that coat condition, and therefore coat colour, is linked very closely to diet. While a horse might get the very best diet for their health, some owners use supplements (such as paprika) to specifically target coat colour, while others do not.
Lastly, I would like to see a lot more grullas being tested for agouti. Brown based dun can mimic grulla, just like brown based roan can mimic blue roan.