This site requires the Adobe Flash Player.
straightegyptians

Welcome Guest ( Log In | Register )

4 Pages V   1 2 3 > »   
Reply to this topicStart new topic
> Colours & Genetics
corsu
post Jul 19 2012, 06:52 AM
Post #1


Advanced Member
***

Group: Members
Posts: 93
Joined: 24-April 10
From: Belgium
Member No.: 35141



A question, can a brown stallion produce chestnut with a grey mare?

I have bred a chestnut colt from 2 greys (I believe) which didn't come as a surprise considering the dominant chestnuts in the pedigree but since the chestnut colt is probably turning rabicano and daddy stays as dark as last year and the year before I'm wondering if he could not be a rabicano brown (although the brown would come from really far away). Bellow a few pictures of the sire (straight Egyptian 4 year old) that I believe to turn grey but doesn't seem to be coming through

Somewhere in the back of my head I had a pop-upp that brown x grey could not produce chestnut
Attached thumbnail(s)
Attached Image
Attached Image
Attached Image
 
Go to the top of the page
 
+Quote Post
barbara.gregory
post Jul 19 2012, 09:19 AM
Post #2


Gold Member
Group Icon

Group: Members
Posts: 1768
Joined: 22-March 03
From: Bury St Edmunds, UK
Member No.: 202



Chestnut is recessive so two chestnuts will always produce a chestnut. Grey is dominant so a HOMOZYGOUS grey will always produce grey whatever colour the other horse is. However two heterozygous greys, by the law of averages, will produce three greys and one colour (depending on what genes they carry) for every four foals. Of course, they may always produce greys or more than one "coloured" foal, this is just the law of averages. I thought a brown stallion could produce a cheatnut but I may be wrong, I am sure there are others who will know for sure.

Barbara
Go to the top of the page
 
+Quote Post
rhoni
post Jul 19 2012, 10:00 AM
Post #3


Senior Member
*****

Group: Members
Posts: 222
Joined: 8-May 04
From: Scotland
Member No.: 1347



Dad could still be a grey - pictured (right) is my stallion Samsara Zaghalll at age eight, who is registered as black/brown but has been genetically tested as GREY. He is showing a few grey hairs through his coat and a silver core to his tail but could never be described as grey by his appearance at this age, very much looking like rabicano. Also pictured, his (definitely) chestnut three year old daughter (also with rabicano markings)
Attached thumbnail(s)
Attached Image
Attached Image
 
Go to the top of the page
 
+Quote Post
amysouthworth
post Jul 19 2012, 10:57 AM
Post #4


Advanced Member
***

Group: Members
Posts: 95
Joined: 27-August 08
From: UK
Member No.: 19428



I always use this website for colour calculating!

http://www.horsetesting.com/ccalculator1.asp
Go to the top of the page
 
+Quote Post
tracek
post Jul 19 2012, 11:12 AM
Post #5


Advanced Member
***

Group: Members
Posts: 158
Joined: 6-November 03
From: Australia
Member No.: 945



Yes, if the brown stallion has a chestnut ancestor and the mare has a chestnut ancestor. smile.gif

Go to the top of the page
 
+Quote Post
Robert 1
post Jul 19 2012, 01:38 PM
Post #6


Gold Member
Group Icon

Group: Senior Member
Posts: 2814
Joined: 14-November 05
From: Pennsylvania USA
Member No.: 2895



QUOTE (barbara.gregory @ Jul 19 2012, 10:19 AM) *
Chestnut is recessive so two chestnuts will always produce a chestnut. Grey is dominant so a HOMOZYGOUS grey will always produce grey whatever colour the other horse is. However two heterozygous greys, by the law of averages, will produce three greys and one colour (depending on what genes they carry) for every four foals. Of course, they may always produce greys or more than one "coloured" foal, this is just the law of averages. I thought a brown stallion could produce a cheatnut but I may be wrong, I am sure there are others who will know for sure.

Barbara

I have yet to believe there is HOMOZYGOUS grays, blacks, bays in any Arabian horses, because for this to happen the pedigree would need to be nothing but that particular color for at least SEVEN generations or more. Yes, Chestnuts are recessive genes, same as white color in German Shepard dogs. To the original post, you answered your own question with your resulting foals. The only color that has been culled out of the Arabian horse is large white spots over six inches and this is now becoming and being called a color.
Go to the top of the page
 
+Quote Post
MHuprich
post Jul 19 2012, 02:05 PM
Post #7


Senior Member
*****

Group: Members
Posts: 488
Joined: 19-April 03
From: Georgia, USA
Member No.: 338



QUOTE (Robert 1 @ Jul 19 2012, 09:38 AM) *
I have yet to believe there is HOMOZYGOUS grays, blacks, bays in any Arabian horses, because for this to happen the pedigree would need to be nothing but that particular color for at least SEVEN generations or more. Yes, Chestnuts are recessive genes, same as white color in German Shepard dogs. To the original post, you answered your own question with your resulting foals. The only color that has been culled out of the Arabian horse is large white spots over six inches and this is now becoming and being called a color.


Since there is a test for homozygous for grey it is believable according to modern science. I know of a horse that is homozygous for grey and he has chestnut in only the second generation back.

Where did you get the info it takes at least 7 generations to get homozygous? Please share the math for this genetic calculation.
Go to the top of the page
 
+Quote Post
anitae
post Jul 19 2012, 07:50 PM
Post #8


Advanced Senior Member
******

Group: Members
Posts: 740
Joined: 23-November 04
Member No.: 1964



Corsu,

I want to clarify if you mean brown or bay. I am assuming from the picture that this is what we would call a bay horse (black mane/tail/lower legs).

In that case, a grey and bay can certainly produce a chestnut. Below is an explanation of how this can happen, but you should understand that there are three different sets of genes that can affect coat color, not a matter of several versions of a single "color" gene.

The three sets of genes have different influences on color. One determines the "base" color (chestnut or black). The other two gene sets are "modifiers" that can influence the basic coat color of black or chestnut. Bay and grey aren't, in a sense, different "colors" at the same level as chestnut or black. They are modifications of the base color.

One of the modifiers (called the "agouti" because this type of modification was first identified in a rodent called an agouti) determines whether a black horse will, instead, be bay because the gene limits the black hair distribution. The other modifier influences whether the horses that would otherwise be black, chestnut, or bay will eventually become gray.

1. Every horse has 2 genes that determine if the horse base coat color is chestnut or black. Chestnut is recessive (e), so to be chestnut the horse has both copies of the recessive form of the gene . If black, the horse has either one or two copies of the dominant version (E) - so a chestnut horse is ee and a black is either Ee or EE.

2. IF the horse would be black (per #1), AND if it has either one or two copies of the gene (called "agouti") that limits the black to the "points" (mane, tail, legs), then the horse will be bay. (A for the dominant; a for the recessive/non-bay). So a bay horse has to be either Ee or EE AND it has to be either AA or Aa.

3. Any horse that is grey has all the possibilities of chestnut/black and agouti or not. The grey is a completely different gene. If it is inherited in the dominant form, it causes the horse to lose the color in the hair. G is for dominant; g is recessive (not grey)

So, the bay horse has at least one dominant "black" gene (E), but could also have one "chestnut" gene (e). It could be "Ee" and it has to be "Aa or AA" to be bay AND it must be "gg" because it is not grey.

The grey horse can have any combination of black/chestnut/agouti. To produce chestnut the horse only has to be Ee. so it can pass on the 'e'. It might be aa or AA or Aa for agouti. To produce a chestnut, the grey parent has to be Gg so it can pass on the 'g' .

If the bay passes on its one chestnut gene, and if the grey horse has at least one chestnut gene and passes it on, then the foal can be chestnut. Because there is no black hair to be influenced by the agouti gene, it doesn't matter whether the foal has "AA" or "Aa" "aa" - you won't see any influence of whatever the underlying gene situation is for the agouti pair of genes.

The bay can't pass on any gene that would cause the foal to go grey.

However, this also means that the gray parent must have one dominant gray (that's why that parent is grey), and one "recessive" (won't cause the foal to go grey). So if the grey parent also passes on the "recessive" form of the greying gene (won't go grey), then the foal will stay chestnut.

Please post any further questions. This can be quite confusing until you get the basic concept that each of the three genes can have different combinations and that two of the gene sets are modifiers, not "independent" colors.
Anita


Go to the top of the page
 
+Quote Post
anitae
post Jul 19 2012, 07:55 PM
Post #9


Advanced Senior Member
******

Group: Members
Posts: 740
Joined: 23-November 04
Member No.: 1964



QUOTE (tracek @ Jul 19 2012, 04:12 AM) *
Yes, if the brown stallion has a chestnut ancestor and the mare has a chestnut ancestor. smile.gif


You are right - but with one qualification: the chestnut (recessive) form of the gene has to exist in both the immediate parents. Of course, parents get their genes from their parents, etc., so there has to be chestnut in the pedigree from ancestors on both sides. But some folks (not you, but others with whom I've spoken) seem to think a color can "jump" generations. The truth is that the genes that determine coat color are in the parents. The "surprise" color comes, typically, when you get a recessive expression that people didn't expect - such as a chestnut from two greys, with their parents in turn being grey or bay or black. There might not be a chestnut "showing" for several generations, but if the recessing 'e' comes down into both parents, then they can produce a chestnut foal (depending, of course, on the grey influence).

Anita
Go to the top of the page
 
+Quote Post
Robert 1
post Jul 20 2012, 01:34 AM
Post #10


Gold Member
Group Icon

Group: Senior Member
Posts: 2814
Joined: 14-November 05
From: Pennsylvania USA
Member No.: 2895



QUOTE (MHuprich @ Jul 19 2012, 04:05 PM) *
Since there is a test for homozygous for grey it is believable according to modern science. I know of a horse that is homozygous for grey and he has chestnut in only the second generation back.

Where did you get the info it takes at least 7 generations to get homozygous? Please share the math for this genetic calculation.

Anything within SEVEN generations is possible of showing up given enough breeding by that horse, this is not saying it will as Anita so well explained but, it is possible. This is why those unexpected colors come up every so few and far between.
I know about the testing for homozygous, and it just dosen't hold water unless for example which ever color it is that is homozygous,every horses in the pedigree for seven generations must be that color. The parents determine the color as do there parents and so on.
Which stallion is tested to be homozygous grey? Ansata focused on grey color for over forty years but still had the occasional colored horse.
Go to the top of the page
 
+Quote Post
Robert 1
post Jul 20 2012, 01:36 AM
Post #11


Gold Member
Group Icon

Group: Senior Member
Posts: 2814
Joined: 14-November 05
From: Pennsylvania USA
Member No.: 2895



QUOTE (MHuprich @ Jul 19 2012, 04:05 PM) *
Since there is a test for homozygous for grey it is believable according to modern science. I know of a horse that is homozygous for grey and he has chestnut in only the second generation back.

Where did you get the info it takes at least 7 generations to get homozygous? Please share the math for this genetic calculation.

Anything within SEVEN generations is possible of showing up given enough breeding by that horse, this is not saying it will as Anita so well explained but, it is possible. This is why those unexpected colors come up every so few and far between.
I know about the testing for homozygous, and it just dosen't hold water unless for example which ever color it is that is homozygous,every horses in the pedigree for seven generations must be that color. The parents determine the color as do there parents and so on.
Which stallion is tested to be homozygous grey? Ansata focused on grey color for over forty years but still had the occasional colored horse.
Go to the top of the page
 
+Quote Post
MHuprich
post Jul 20 2012, 02:12 AM
Post #12


Senior Member
*****

Group: Members
Posts: 488
Joined: 19-April 03
From: Georgia, USA
Member No.: 338



Ecaho homozygous grey with one bay grandparent

Where did you get the info it takes at least 7 generations to get homozygous? Please share the math for this genetic calculation and the source of the belief it takes 7 generations.

Thanks
Go to the top of the page
 
+Quote Post
alythlong
post Jul 20 2012, 05:33 AM
Post #13


Member
**

Group: Members
Posts: 30
Joined: 8-November 04
Member No.: 1834



QUOTE (Robert 1 @ Jul 20 2012, 03:34 AM) *
Anything within SEVEN generations is possible of showing up given enough breeding by that horse, this is not saying it will as Anita so well explained but, it is possible. This is why those unexpected colors come up every so few and far between.
I know about the testing for homozygous, and it just dosen't hold water unless for example which ever color it is that is homozygous,every horses in the pedigree for seven generations must be that color. The parents determine the color as do there parents and so on.
Which stallion is tested to be homozygous grey? Ansata focused on grey color for over forty years but still had the occasional colored horse.



Anitae is correct....we are dealing with 3 sets of genes here.

Bay/black/brown is half of one pair with the recessive chestnut. You could have 100 generations of heterozygous bbb parents still produce a chestnut foal....it all depends on the random selection at fertilization.

The agouti gene decides the patterning of the black colouring - all over or limited to points or mixed with brown hairs.

The grey modifying gene. All grey horses have one grey parent. If both parents are grey you might get a homozygous grey foal, which is still born a base colour (bbb or chestnut) and will turn grey.

There are other pairs of genes that affect Arabians - one of them being sabino - the white patterning, including "roaning". But I haven't studied these in detail....

Go to the top of the page
 
+Quote Post
anitae
post Jul 20 2012, 05:49 AM
Post #14


Advanced Senior Member
******

Group: Members
Posts: 740
Joined: 23-November 04
Member No.: 1964



QUOTE (alythlong @ Jul 19 2012, 10:33 PM) *
....

There are other pairs of genes that affect Arabians - one of them being sabino - the white patterning, including "roaning". But I haven't studied these in detail....


Here's a bit more information about sabino and roan. The sabino gene found in other breeds is not found in Arabians. In other breeds (such as Quarter horse) it is the SB1 gene. That gene, however, has not been found in Arabians. So we don't know yet what causes the sabino-like markings in Arabians. Similarly, we don't yet have a simple genetic explanation for roaning.

Another yet-to-be-identified is what causes the rabicano markings like "skunk" tail.

More research to be done!!!

Anita
Go to the top of the page
 
+Quote Post
alythlong
post Jul 20 2012, 08:14 AM
Post #15


Member
**

Group: Members
Posts: 30
Joined: 8-November 04
Member No.: 1834



QUOTE (anitae @ Jul 20 2012, 07:49 AM) *
Here's a bit more information about sabino and roan. The sabino gene found in other breeds is not found in Arabians. In other breeds (such as Quarter horse) it is the SB1 gene. That gene, however, has not been found in Arabians. So we don't know yet what causes the sabino-like markings in Arabians. Similarly, we don't yet have a simple genetic explanation for roaning.

Another yet-to-be-identified is what causes the rabicano markings like "skunk" tail.

More research to be done!!!

Anita



In the US you don't recognise extreme sabino Arabians do you? We have one here - a "medicine hat" purebred Arabian that is pure white with a teeny bit of brown around the edges of her ears....dna'd as pure. She was "not judged" at our National show by a US judge, we think because of her colour. And I believe there was one in Oz quite a few years ago, before current knowledge was available and many people thought he was "impure" because of his colour....So is the sabino gene in Arabians SB2? I am sure there is still a lot more to be learned!!!
Go to the top of the page
 
+Quote Post

4 Pages V   1 2 3 > » 
Reply to this topicStart new topic

 

Lo-Fi Version Time is now: 21st October 2014 - 15:09
This site requires the Adobe Flash Player.