jelibean
Well-Known Member
At the risk of being the thickest person in the world, please could someone explain to me the meaning of red factor and Agouti (Heterozygous agouti) in colour genetics.
Ta
Ta
I dont understand.
- Thread starter jelibean
- Start date
Anastasia
Well-Known Member
LOL.........dont look at me for any help.......have never got my head round the colour factors of some horses!
ashbank
Well-Known Member
The Extension gene (E) which is associated with red factor means that the horse will have black hair in the coat (EE or Ee). Lack of extension (ee) means the horse is chestnut.
The Agouti gene (A) determines the distribution of black hair. In it's dominant form (AA or Aa) the horse will be bay - with the black hair limited to the points. In it's recessive form (aa) the black hair is evenly distributed throughout the coat - ie the horse is black.
Heterozygous Agouti along with E means the horse is bay (in the absence of any modifying genes such as cream/tobiano/grey etc)
HTH
The Agouti gene (A) determines the distribution of black hair. In it's dominant form (AA or Aa) the horse will be bay - with the black hair limited to the points. In it's recessive form (aa) the black hair is evenly distributed throughout the coat - ie the horse is black.
Heterozygous Agouti along with E means the horse is bay (in the absence of any modifying genes such as cream/tobiano/grey etc)
HTH
Fahrenheit
Well-Known Member
I gave up claiming I had any knowledge on colour genetic ages ago! After the Black debate where I was told it was dominant when its recessive....
I think all colour queries should be directed to Ashbank
he can be our colour genes expert
, just like AP is the fertility and AI expert
I think all colour queries should be directed to Ashbank
jelibean
Well-Known Member
Thankyou very much ashbank, that helps a little, it seems very complex.
ashbank
Well-Known Member
[ QUOTE ]
I think all colour queries should be directed to Ashbank
he can be our colour genes expert
[/ QUOTE ]
Hey! Why have I been demoted to male??!! And you're right, black is recessive.
Jelibean - I will be happy to answer any specific questions on colour if you'd like, although I'm not sure I am an expert!
I think all colour queries should be directed to Ashbank
[/ QUOTE ]
Hey! Why have I been demoted to male??!! And you're right, black is recessive.
Jelibean - I will be happy to answer any specific questions on colour if you'd like, although I'm not sure I am an expert!
pocomoto
Well-Known Member
[ QUOTE ]
At the risk of being the thickest person in the world, please could someone explain to me the meaning of red factor and Agouti (Heterozygous agouti) in colour genetics.
[/ QUOTE ]
I don't think you are thick at all many people don't make the effort to even look at colour inheritance and are unaware of the terms red factor and agouti, many of them breed some form of colour!!
Simply put (I think), E is the so called extension series gene and is written EE or Ee if it is present, this indicates that a horse has a black base coat from the presence of a pigment and a lack of the extension gene is depicted as ee, this indicates that there is no dominant black pigment so the recessive red can express itself and the horse is a chestnut. Black is dominant over chestnut so a horse that is EE (homozygous black) will never produce a chestnut but a horse that is Ee can, if it is bred with a chestnut ee or another like itself Ee and the offspring does not inherit E ie it is ee.
The Agouti A , only has a known visible effect on the black base coated horse , (though it might well influence coat shade but this is pure theory) If it is present (AA or Aa) and meets a black coat it will change that coat to leave black just at the extremities in the bay, brown/tan at the extremities in the seal brown or make a horse brown all over. A lack of the agouti gene aa means that the E gene if present is unaffected and the horse stays black.
(Agouti is combined with brown for testing results, since the scientists are currently unable to establish the difference in the number of nucleotides * that separate the agouti coat colours. I.e. the bay, the brown and the seal brown (blackish with brown/tan soft parts)).
(don't read this bit if you are confused! - Then there is the theory of the dominant black reported by some Frisian breeders, which if it does exist is a gene on a different locus that effectively overrides A !!!)
It's often not mentioned that the presence of A has no obvious effect on the chestnut base coat but that chestnuts carry A which only comes into play when it eventually meets E?. So as a result a chestnut can be incapable of producing a black if it has the genotype AA.
*(the structural components of DNA and RNA used to distinguish the presence or absence of specific genes)
Hope that helps!
At the risk of being the thickest person in the world, please could someone explain to me the meaning of red factor and Agouti (Heterozygous agouti) in colour genetics.
[/ QUOTE ]
I don't think you are thick at all many people don't make the effort to even look at colour inheritance and are unaware of the terms red factor and agouti, many of them breed some form of colour!!
Simply put (I think), E is the so called extension series gene and is written EE or Ee if it is present, this indicates that a horse has a black base coat from the presence of a pigment and a lack of the extension gene is depicted as ee, this indicates that there is no dominant black pigment so the recessive red can express itself and the horse is a chestnut. Black is dominant over chestnut so a horse that is EE (homozygous black) will never produce a chestnut but a horse that is Ee can, if it is bred with a chestnut ee or another like itself Ee and the offspring does not inherit E ie it is ee.
The Agouti A , only has a known visible effect on the black base coated horse , (though it might well influence coat shade but this is pure theory) If it is present (AA or Aa) and meets a black coat it will change that coat to leave black just at the extremities in the bay, brown/tan at the extremities in the seal brown or make a horse brown all over. A lack of the agouti gene aa means that the E gene if present is unaffected and the horse stays black.
(Agouti is combined with brown for testing results, since the scientists are currently unable to establish the difference in the number of nucleotides * that separate the agouti coat colours. I.e. the bay, the brown and the seal brown (blackish with brown/tan soft parts)).
(don't read this bit if you are confused! - Then there is the theory of the dominant black reported by some Frisian breeders, which if it does exist is a gene on a different locus that effectively overrides A !!!)
It's often not mentioned that the presence of A has no obvious effect on the chestnut base coat but that chestnuts carry A which only comes into play when it eventually meets E?. So as a result a chestnut can be incapable of producing a black if it has the genotype AA.
*(the structural components of DNA and RNA used to distinguish the presence or absence of specific genes)
Hope that helps!
alleycat
Well-Known Member
Trouble is, you've got to define what you mean by black.
Now we know more about it, it seems to have become more confusing.
As has just been said, a black horse owes its blackness to the action of two genes; the first for black as a colour, the second for the distribution of that colour all over the body instead of just being confined to the points, as in a bay.
The first gene is dominant; (as in bay is dominant to chestnut).
The second gene is recessive (as in two bays carrying this hidden gene could produce black). A chestnut horse can also carry this gene, or two copies of this gene, but it cannot be expressed if there is no black present for it to work on.
This confuses me utterly when the coloured horse people, who seem to like bay- rather than chestnut skewbald, describe their horses as being "homozygous for black" meaning not that they ARE black but that they can't produce a chestnut, I think......
Edited to say that pocomoto has just beaten me to it, and with longer words!
Also one thing I can't fathom is how a chestnut horse, which shouldn't carry the gene for black in its coat at all, can often have quite a lot of black hair in its mane, as if bay-ness had been supressed. Any ideas on how this works?
Now we know more about it, it seems to have become more confusing.
As has just been said, a black horse owes its blackness to the action of two genes; the first for black as a colour, the second for the distribution of that colour all over the body instead of just being confined to the points, as in a bay.
The first gene is dominant; (as in bay is dominant to chestnut).
The second gene is recessive (as in two bays carrying this hidden gene could produce black). A chestnut horse can also carry this gene, or two copies of this gene, but it cannot be expressed if there is no black present for it to work on.
This confuses me utterly when the coloured horse people, who seem to like bay- rather than chestnut skewbald, describe their horses as being "homozygous for black" meaning not that they ARE black but that they can't produce a chestnut, I think......
Edited to say that pocomoto has just beaten me to it, and with longer words!
Also one thing I can't fathom is how a chestnut horse, which shouldn't carry the gene for black in its coat at all, can often have quite a lot of black hair in its mane, as if bay-ness had been supressed. Any ideas on how this works?
Anastasia
Well-Known Member
Am going to hijack this thread for one second. Whats the name of the website where you can get your horse checked for the red gene?? I know someone posted it on here but I dont want to troll through all the threads again....
Anastasia
Well-Known Member
This might as well be in swaheli for all I understand.......
Can someone not write this in the form of the "Idiots guide to horse colours.......?"
So if I have a mare who has three sires who are all black, and her dam and grand-dam are also black......what are the chances of her producing a chesnut and also a black?
Can someone not write this in the form of the "Idiots guide to horse colours.......?"
So if I have a mare who has three sires who are all black, and her dam and grand-dam are also black......what are the chances of her producing a chesnut and also a black?
alleycat
Well-Known Member
What colour is she, and has she produced any foals yet,; and if so, who to?
Her mum & dad must each carry 2 genes for the colour distribution which produces black rather than bay, as these are recessive; they couldn't be black themselves without having 2 of them. So they must have passed on one each to her. Therefore she should have 2 genes for the black "pattern", if you like, and must pass one on to her foals. For it to produce black instead of bay, the father would also need to pass on the same gene. If she is chestnut (you don't say she's black herself, so I take it she is chestnut?) she will also pass on a gene for chestnut. To get a black foal you need a black "pattern" gene from the sire to complement hers(so you don't get bay) and a black "colour" gene to override her chestnut contribution.
This is if the family are really black, and not just dark brown....
Her mum & dad must each carry 2 genes for the colour distribution which produces black rather than bay, as these are recessive; they couldn't be black themselves without having 2 of them. So they must have passed on one each to her. Therefore she should have 2 genes for the black "pattern", if you like, and must pass one on to her foals. For it to produce black instead of bay, the father would also need to pass on the same gene. If she is chestnut (you don't say she's black herself, so I take it she is chestnut?) she will also pass on a gene for chestnut. To get a black foal you need a black "pattern" gene from the sire to complement hers(so you don't get bay) and a black "colour" gene to override her chestnut contribution.
This is if the family are really black, and not just dark brown....
Damien
Well-Known Member
Avian Biotech Avian Biotech
It doesn't really matter, (well it will infleunce the outcome) but what is important is that one of the parents does not carry the red factor
But even they don't you could still get a bay foal
Reason being that chestnuts have two copies of the red gene -one passed on from each parent. If one parent does not carry the red gene the foal can never be chestnut.
It doesn't really matter, (well it will infleunce the outcome) but what is important is that one of the parents does not carry the red factor
But even they don't you could still get a bay foal
Reason being that chestnuts have two copies of the red gene -one passed on from each parent. If one parent does not carry the red gene the foal can never be chestnut.
Anastasia
Well-Known Member
Alleycat she is black herself. Her sire line is De Niro (Donnerhall) x Hohenstein x Rubinstein. Her mum is black as is her grand dam... she has not produced any foals yet. Her mum has produced blacks and bay and produced a dark bay colt this year to Diamond Hit.
Fahrenheit
Well-Known Member
[ QUOTE ]
[ QUOTE ]
I think all colour queries should be directed to Ashbank
he can be our colour genes expert
[/ QUOTE ]
Hey! Why have I been demoted to male??!! And you're right, black is recessive.
Jelibean - I will be happy to answer any specific questions on colour if you'd like, although I'm not sure I am an expert!
[/ QUOTE ]
Sorry slip of the keyboard
[ QUOTE ]
I think all colour queries should be directed to Ashbank
[/ QUOTE ]
Hey! Why have I been demoted to male??!! And you're right, black is recessive.
Jelibean - I will be happy to answer any specific questions on colour if you'd like, although I'm not sure I am an expert!
[/ QUOTE ]
Sorry slip of the keyboard
pocomoto
Well-Known Member
Sorry lets have another go, this may not be conventional as this is how I cope with it!
There are only two base coat colours in the horse black and chestnut. Everything else is a gene that modifies those colours in some way.
Only one base colour can be inherited from each parent, but each parent has two to put into the mix. So part one of the lottery!
The E gene is the one that determines if the coat appears Black or Red (Chestnut).
Big E as I like to call it means that the horse has inherited black from a parent and Big E Big E means that it has inherited one Big E from each parent. You only need one E to make a black coat and two Es means that that horse will only ever produce a black base coat.
In a genetic fight Big E wins out over little e which then sits in the background. So the old adage from pre genetics horse breeding is proven, breed a chestnut to a chestnut and you will always get a chestnut so a chestnut is always little e little e, because if that horse had a big E it would be black.
So Big E Big E is homozygous (the same) for a black base coat and will win out over chestnut, it is dominant.
Big E Little E Is a black coat carrying the chance of a chestnut, so in the right circumstances as below you can get a chestnut:
Little e Little e is always a chestnut.
A = Agouti but sometimes I wonder if this is where the problem lies only has a visible effect on the black base coat (so its more like the extension you see in dogs and other more well studied animals). Same principle here Big A Big A or Big A Little a means it has Agoui Little a Little a means it hasnt.
Agouti is a separate gene from the base colours and only has a visible effect on the black base coat, so in effect a chestnut can still carry the A quietly until it is finally passed on to a foal that also has one or two big Es (a black) . Then this up till now silent big A will produce a brown, seal brown or bay from that black coat. So if a chestnut is carrying two big As you cant get a true black coat, but it might be very dark brown!
If you are still stuck I have an article somewhere with diagrams that I can send you.
http://www.horsedna.co.uk/ is the cheapest ive come across this side of the pond but check out USA with the dollar rate at the mo, you only need to send some mane or tail hairs.
There are only two base coat colours in the horse black and chestnut. Everything else is a gene that modifies those colours in some way.
Only one base colour can be inherited from each parent, but each parent has two to put into the mix. So part one of the lottery!
The E gene is the one that determines if the coat appears Black or Red (Chestnut).
Big E as I like to call it means that the horse has inherited black from a parent and Big E Big E means that it has inherited one Big E from each parent. You only need one E to make a black coat and two Es means that that horse will only ever produce a black base coat.
In a genetic fight Big E wins out over little e which then sits in the background. So the old adage from pre genetics horse breeding is proven, breed a chestnut to a chestnut and you will always get a chestnut so a chestnut is always little e little e, because if that horse had a big E it would be black.
So Big E Big E is homozygous (the same) for a black base coat and will win out over chestnut, it is dominant.
Big E Little E Is a black coat carrying the chance of a chestnut, so in the right circumstances as below you can get a chestnut:
Little e Little e is always a chestnut.
A = Agouti but sometimes I wonder if this is where the problem lies only has a visible effect on the black base coat (so its more like the extension you see in dogs and other more well studied animals). Same principle here Big A Big A or Big A Little a means it has Agoui Little a Little a means it hasnt.
Agouti is a separate gene from the base colours and only has a visible effect on the black base coat, so in effect a chestnut can still carry the A quietly until it is finally passed on to a foal that also has one or two big Es (a black) . Then this up till now silent big A will produce a brown, seal brown or bay from that black coat. So if a chestnut is carrying two big As you cant get a true black coat, but it might be very dark brown!
If you are still stuck I have an article somewhere with diagrams that I can send you.
http://www.horsedna.co.uk/ is the cheapest ive come across this side of the pond but check out USA with the dollar rate at the mo, you only need to send some mane or tail hairs.
Anastasia
Well-Known Member
LOL.........trust you HG to get the sex wrong..........
Thanks Opie for the link........
x
Thanks Opie for the link........
alleycat
Well-Known Member
Then she has to pass on the black PATTERN (rather than just dark points as in bay) but to get a black foal (rather than bay), you would need the sire to do likewise. If he is black, he must; but if he is any other colour (including chestnut) he could still be hiding this recessive gene for black pattern.
However, you would also need at least one gene from either parent for black, rather than red, HAIR COLOUR. As chestnut is recessive, you don't know whether the mare is hiding it (hence the test?) . If she had had a chestnut parent you would know that she had received one gene for chestnut; but hers were both black. The foal only needs one black hair colour gene to be black or bay (depending on the pattern genes it had inherited) as this gene is dominant. So if the mare doesn't carry chestnut you can be sure that she can never give you chestnut.
If the red factor test shows you that she doesn't carry chestnut and you put her to a black stallion, she & he should always produce black.
Even if she does carry chestnut, if you put her to another stallion who isn't chestnut but carries it, you've only got a 1 in 4 chance of producing chestnut, as the foal will need to inherit both genes for chestnut before ithe colour can be expressed.
I did this myself a couple of years ago with 2 mares; bay to bay (to produce bay) and palomino to palomino ( to produce cremello). What did I get?...... 2 chestnuts........
However, you would also need at least one gene from either parent for black, rather than red, HAIR COLOUR. As chestnut is recessive, you don't know whether the mare is hiding it (hence the test?) . If she had had a chestnut parent you would know that she had received one gene for chestnut; but hers were both black. The foal only needs one black hair colour gene to be black or bay (depending on the pattern genes it had inherited) as this gene is dominant. So if the mare doesn't carry chestnut you can be sure that she can never give you chestnut.
If the red factor test shows you that she doesn't carry chestnut and you put her to a black stallion, she & he should always produce black.
Even if she does carry chestnut, if you put her to another stallion who isn't chestnut but carries it, you've only got a 1 in 4 chance of producing chestnut, as the foal will need to inherit both genes for chestnut before ithe colour can be expressed.
I did this myself a couple of years ago with 2 mares; bay to bay (to produce bay) and palomino to palomino ( to produce cremello). What did I get?...... 2 chestnuts........
Anastasia
Well-Known Member
OMG brain overload...............I am seeing "E"'s flashing in front of my eyes
. OK, I need to digest this and see if I can understand what you are saying......thanks for all the info.........takes something else to get your head round it......