Anyone want to know about greys and roans...?

[chev]

Greys first, because they're nice and easy to understand.

Grey acts as a dominant gene, and some consider it technically not a colour gene but a colour-replacing gene. A horse only needs one copy of grey to go grey. Greying is not related to age - horses that will go grey show signs of doing so as early as six months old, when they start to shed the baby coat.

Interestingly, foals that will go grey are often born a deeper colour than those that don't. For example; a bay horse will usually be born with fawn coloured legs - it's only when they shed the foal coat that the black points show up. A bay foal destined to go grey will often be born with a deep bay coat and black legs.

Greys don't just grow white hair - the first stage of the greying process also adds black hair, so some colours will appear to get darker instead of lighter as they grow.

All greys, if they live long enough, will end up white. They will go through a variety of interesting stages to get there though. The first signs are often no more than a sprinkling of white hairs, leading to some confusing their grey for a roan.

Steel greys develop from black horses; rose greys from horses with a red base. At this stage, they are still easy to confuse with roans.

Next stage is dapple grey - by this point it's obvious that a horse is going grey, and not a roan. Some horses remain dapple grey (sometimes quite dark too) for years, while others are completely white by six or seven.

Some greys that have gone white will then develop flea-bitten markings, where they show freckles of black or brown.

Some pictures of grey....

First is Gelfy when we first has him. His body was still very brown - almost roaned, to look at - but note how although his body and points might fit the roan description his face is much whiter. If he'd been roan, his head would have had little or no white on it at all.

 

[chev]

Next stage - rose grey. He's really obviously going grey now, but still has enough bay pigment to make him a very reddish grey.

 

[chev]

This stage shows the dappling to good effect, although lots of dapple greys are much darker. He's well on his way to being white now. His mane and tail are getting paler now too, and his legs show some odd patches as they grey out.

 

[chev]

And this is how he'll eventually end up... This one is May, who was white when we bought her, at just six. She's now starting to show signs of freckles - her flanks have a brown ticking on them in the summer, so she may go fleabitten over the next few years.

Edited to add Gelfy's continuing into grey... He's now white all over and has started developing fleabites mainly in the face. Not great piccies (taken on OH's phone) but hopefully you can see the developments...

 

[chev]

And roan...

Roan mixes white hair evenly with a horse's base colour. The head and lower legs remain solid with very little or no white.

Roan may not be apparent when a foal is born, but once the foal coat is shed and roan is visible, it remains stable throughout the horse's life. Roan is not progressive - roan horses do not get greyer through life. Nor do they develop later in life - a roan will be roan at birth. Roans do, however, often vary according to the season - it's not uncommon for a roan to be an obvious roan in summer, and then shed out to a darker more solid looking colour in winter. Often they go through very white phases as the coat changes - but these variations will be the same every year - no tlike Gelfy's whose changes are progressive over time.

Roan is not related to Varnish Roan patterns in Appaloosas - Varnish roan is another progressive pattern that gradually overtakes the base colour.

Terminology is confusing with roans - these are one version!

Roan on black - blue roan. Head and lower legs will be black, body mixed with white hairs has a grey, or blue appearance.

Roan on bay - bay or red roan. Again, head remains bay, and the black points remain black, while the body appears a pinkish colour.

Roan on chestnut - legs, head, mane and tail stay chestnut, body is a pale orangey colour.

Roans also show something known as 'corn marks' - that is, where the skin is damaged, instead of the hair growing back white as it would with a solid horse, it grows back in the base colour - so a bay roan would have bay marks where the skin has been scratched in an otherwise roan coat.

 

[Rips]

Chev your colour threads are brilliant! I think I understand most of what has been said in all three but I still can't figure out my own mare's genes.

If a horse has one grey parent does it have to throw a grey horse? Can a grey have a foal that won't grey out? A brown horse...

 

[horseygal90]

Your threads are really interesting me - We've only touched genes in Biology at the minute, and it is a subject I enjoy looking at.

 

[chev]

Grey is another simple dominant. A horse only needs one copy of the grey gene to go grey - which it gets from one parent or another.

So, if a horse is grey, at least one of its parents must also have been grey.

If a horse has one grey gene (heterozygous for grey) there's a 50/50 chance it'll pass that gene on and throw grey - so yes, a heterozygous grey can have a non-grey foal.. If, however, it has two grey genes, it'll always throw grey.

This is why greys are best avoided in colour breeding programs - nothing more depressing than watching your beautifully marked tobiano foal getting greyer, and greyer....

 

[Rips]

Interesting, so I know then my mare definately is heterozygous for grey because her dam was grey.

What about brown (she's registered as brown) is this gene like bay? Her sire was a bay from a line of bays and blacks.

While she's registered as brown, and does go very brown sometimes even her mane, she always has black legs and does go almost completely black at some times of the year.
She doesn't have any white hairs or markings.

 

[chev]

Brown is bay with the addition of a sooty gene - this can turn bay into bay with countershading (that could be as little as a stripe resembling a dorsal stripe) through mahogany bay to dark bay. It's also now believed that the sooty gene is also what causes seal brown, as many seal brown horses are shown to have the Agouti gene (and therefore a bay base) when tested.

If your mare is brown, and showing no signs of grey, then she's not heterozygous for grey - that would mean she has a grey gene. This we know she doesn't - because she's not grey!

Because we don't know what colour her dam is 'under' the grey, it's hard to say what colour she's got from which parent.

 

[Rips]

Ok, so she got a non-grey gene from her grey dam,who had to be heterozygous, but we can't know what that gene is. Gotcha

Well at least then I know she doesn't carry a grey gene
Thanks Chev, you should write a book... "Genetics for idiots"

 

[chev]

Originally posted by Rips
Ok, so she got a non-grey gene from her grey dam,who had to be heterozygous, but we can't know what that gene is. Gotcha

Well at least then I know she doesn't carry a grey gene
Thanks Chev, you should write a book... "Genetics for idiots"

Almost. She just didn't get a grey gene. Grey genes are separate to base colour genes - it's a bit like an optional extra on a car, if you like! If the base colour of car is blue - the grey gene would be like the option of a metallic finish. It doesn't change the fact that the car is blue - but it does change the way it looks.

The book.... that'd be what I read before I got my head round it!!

 

[~Perdita.M~]

These threads are fascinating Chev, thanks! Can't get over the difference in Gelfy, the first one looks like he's been rolling in a ditch The only interesting things that shams coat does.....um.......in winter he gets some darker grey patches on his hind legs, and........um........he has ONE fleabitten chestnut bit on his neck at all times

 

[Bobbi77]

Originally posted by chev
And roan...


Roan on chestnut - legs, head, mane and tail stay chestnut, body is a pale orangey colour.

This is pretty interesting stuff! Just one thing - our pony is chestnut roan and she is pale orangey - darker in winter - but her mane and tail aren't exactly chestnut - more a dirty grey colour. Ithink she's lovely all the same

 

[chev]

How old is she and do you know what colour her parents were Bobbi? It's possible she has grey - see how her face has white mixed in with it? That's typical of greying, not roan - a roan has no white on the face at all (markings aside, obviously).

So (particularly if she's young still) she could be following a greying pattern and not actually roan at all - greying can look astonishingly like roan at times. She could also be a roan with grey - the grey would slowly overtake the roan pattern and hide it.

Or, she could have sabino in there - very very likely given the white markings on her face - that could cause the roaning too. She could be sabino with roan (which is why her ears are darker - roan works on the body not the head, and sabino working on her face, leaving her ears free from roaning!) or the roaning could be an extensive form of sabino.

The grey in her mane could be unconnected with either - I have a liver chestnut with the same grey mane and tail - if she carried roan as well she'd have the same kind of patterning.

Your pony doesn't look like a classic roan - it could be something else causing the pattern, or roan and something else. If one of her parents is a classic roan it would be easier to say for sure what genes she might be carrying - if neither parent is roan, it's also easy to see she isn't a classic roan. I'd guess at classic roan with extensive sabino roaning on top. Does she have lots of white on her legs or belly?

Whatever she is (and I'm intrigued now!) she's a remarkably pretty pony.

 

[chev]

Perdita - it's even more astonishing when you consider that Gelfy was probably a lovely rich bay with black points when he was born too! Seems a shame somehow that he'll end up white after all that....

 

[Bobbi77]

Chev, she does have white legs - I have attached a pic that was taken about a year ago. She is rising 4. Her mother was grey and her father was bay. She goes a lovely peachy colour in the summer - almost pink!

 

[chev]

She is pretty! That's a definite sabino too - the roaning, the white face, the ragged legs - she's absolutely classic.

So we still don't know if she's a true roan since her mother's colour was hidden under grey - she still doesn't look convincing to me though. Very difficult to judge when the sabino is hiding what dark points she would have, but with the possibility of her having inherited grey from mum as well.... My guess would be chestnut sabino greying out, to be honest. The roaning on her body just isn't even enough to be as a result of roan.

She is absolutely gorgeous though!

 

[Bobbi77]

Thanks for that info Chev - I've learnt something new now!

I think she's pretty but I'm a little biassed. At the moment she is a scruffy little madam as she has been turned out for the past 4 months to have some fun! Unfortunately, we will probably be selling her this spring - will be upsetting but Fern will probably have outgrown her by the time she is ready to do any real work with her, and we can't afford to keep two ponies!

She is a lovely little pony though - we adore her

 

[Stiltz]

what about this one?

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