Colour Genetics Help Please- Lots of Pictures

catroo

catroo

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Basically is my pony black or brown? What colour genes do you think he has? His mum is black (I'd call her a fading black rather than a true black) and dad is a chestnut (bright orange). His colour changes depending on season/length of coat, here are some pictures showing what I mean

As a foal (couple weeks old)
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Summer coast last year (Yearling)
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Full Double Winter coat (yearling) - very black
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Spring & Autumn Single Winter Coat - reddish brown tinge (this is Spring this year as a two year old)
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Also the white spot on his shoulder comes and goes, it's in his Summer & Double thick Winter coat but not visible in Spring/Autumn.

What colour genes do you think he has? Does he have the Agouti allele? If so would this not of come from his mum?
 
I can see the photos perfectly!
Don't know anything about genes though so can't really help but just wanted to say, its a beautiful pony! :)
 
I can see them..

I'd call him brown purely because even when his coat appears black, his mane doesnt but then I'm no colour expert at all!
 
The first pony book I had as a child gave black-brown as a colour, so I'd call him that :D. But then again that white shoulder patch would mean piebald...or do I mean overo?:p BTW he is gorgeous!
 
He looks like a faded black to me.

It is possible that he needs copper and zinc in his feed as many people with faded blacks have found that their grazing is lacking these minerals. Once the horse has a really good vit&min supplement, the coat grows in black and stays black.
 
Faracat said:
He looks like a faded black to me.

It is possible that he needs copper and zinc in his feed as many people with faded blacks have found that their grazing is lacking these minerals. Once the horse has a really good vit&min supplement, the coat grows in black and stays black.
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Exactly what I was going to say!
 
In the shetland world we call that a Muddy Black. A true black will never fade in the sun and will be black throughout whatever their coat and time of year. Muddy Blacks just look sun bleached lol!
 
Lets call the black genes A's. So a true black will be AA - both parents having given it the A gene. The Muddy Black gene we'll call a. So any pony with an a in it will be muddy - Aa or aa. An aa pony can never produce a true black offspring. An Aa has a 50% chance of it - depending on what the other parent puts in.
 
EKW said:
Lets call the black genes A's. So a true black will be AA - both parents having given it the A gene. The Muddy Black gene we'll call a. So any pony with an a in it will be muddy - Aa or aa. An aa pony can never produce a true black offspring. An Aa has a 50% chance of it - depending on what the other parent puts in.
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Sorry EKW, but that's just not true.

The first gene is called the "E" gene.

It was named the "Extension" locus because the dominant allele, E, "extends" the eumelanin (black pigment). The recessive allele, e, blocks the eumelanin, leaving only phaeomelanin (red pigment). When the black pigment is present, that is what we see, so the horse looks black (in the absence of any further modifying genes, which will be discussed later). Therefore, ee would give a red (chestnut) horse, EE would give a black horse which cannot produce a chestnut foal, and Ee would give a black horse that can produce a chestnut foal. There is now a DNA test which can tell you exactly which "E" genes your horse is carrying. It's especially popular with breeders that are partial to the color black, since a black horse that is EE will never have a chestnut foal, and when bred to another black, will always have a black foal. But the test can come in handy in solving some kinds of color mysteries, too, since some colors can look very similar to each other.

Some older books have theorized that there is a third allele, called ED, dominant to the other two, which would explain the "non-fading black" which is rare, but occasionally seen. However, more recent studies have discounted this theory. It is a fact that some very few black horses do not fade in the sun, but it is unknown at this time what genetic mechanism causes this. One theory that has been conclusively disproved is that the "faders" are Ee, and the "non-faders" are EE. Now that there is a test for the "E" genes, plenty of blacks that fade terribly have been identified as EE, so that can't be the answer.
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Faracat said:
He looks like a faded black to me.

It is possible that he needs copper and zinc in his feed as many people with faded blacks have found that their grazing is lacking these minerals. Once the horse has a really good vit&min supplement, the coat grows in black and stays black.
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Thank you, I'll look at adding those to his diet. He's on a general supplement, because he's on poor grazing to control his weight I worry about him getting all vital nutrients, especially as he's still a youngster
 
A bit of info regarding the copper and zinc theory. It's not proven, but a good vit&min supplement isn't going to do any harm, so worth a go.

A copper dependent enzyme called tyrosinase is responsible for the production of melanin, brownish black pigments synthesised from the amino acid tyrosine. This occurs in plants and animals including micro organisms and us. The lack of tyrosinase activity is responsible for albinism and is related to grey hair in us. Sufficient copper is needed to produce the pigment in buckskins and chestnuts and both copper and zinc are needed for black/brown/grey coats.

The purpose of the pigments is to act as a shield against light. The fading is caused by ultraviolet light oxidising the pigments. If there are less than optimal levels in the diet, the hair will be more prone to bleaching but will look normal until enough pigment has been damaged to cause the colour change.

That’s why a newly grown winter coat will appear darker but then lightens over time if the horse is copper and zinc deficient. If your horse is on a more than adequate nutrient and mineral balanced diet, there is no need for rugging or worse, being kept indoors.

Copper deficiency in other species influences coat quality and produces ‘rusting’ of dark coats, this is especially noticeable in the manes of bays and black horses. This effect in horses has not been formally proven, but horses showing red tips on dark manes of dark coats respond well to copper and zinc supplementation.
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ETA, yes, I think that Ee is highly likely. :)
 
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