# Bay is not a modifier



## KigerQueen (Jun 16, 2013)

WOW! this just blew my mind and i LOVE IT! i have read about 5 post about color genetics from this. so this leads me to wonder where brown fits into this. was it an early mutation that predated black horses? or did it make way for other genetic color variations?


----------



## DraftyAiresMum (Jun 1, 2011)

We say bay is a modifier because it makes it simpler than going into a whole huge long genetics explanation with someone who just wants a simple answer (i.e.-is my horse bay or brown?).


----------



## kassierae (Jan 1, 2010)

Yes but Drafty, brown tests as bay, the brown test has been pulled due to impossible results. So until they find out what really causes brown, it is just a phenotype of bay. It was hard for me to wrap my head around bay not being a modifier because I was initially taught incorrectly. If we teach people the correct information from the start we wouldn't have so many people thinking bay is a modifier. If you aren't already, you should join the equine color genetics page on Facebook. I consider myself extremely knowledgable about genetics, I've been studying them for almost ten years now. But even I learn new things almost daily.
_Posted via Mobile Device_


----------



## blue eyed pony (Jun 20, 2011)

So if agouti isn't a modifier (modifying black), does that mean non-agouti is modifying bay? And therefore all Ee/EE horses are bay-based with aa horses being modified to be black all over?

I think I'm being a little sarcastic with the above ^ but it's also honest curiosity.


----------



## kassierae (Jan 1, 2010)

No, think of red and black as pigment type switches. E is the ability to produce red and black pigment, e is the ability to produce only red pigment. Agouti tells the black where to express. Think of the two loci as a unit, not separate entities.
_Posted via Mobile Device_


----------



## DraftyAiresMum (Jun 1, 2011)

But kassie, Joe Shmoe owner doesn't WANT to know all the technicalities and lingo. They want to know in the plainest terms possible. 

Also, by definition, agouti IS a modifier if it's telling the black where/how to express.
_Posted via Mobile Device_


----------



## blue eyed pony (Jun 20, 2011)

I was definitely being sarcastic more than curious because I do know this 

It's 7am and I haven't slept so don't mind me... I say stuff without knowing why I'm saying it when I'm this tired!


----------



## kassierae (Jan 1, 2010)

But that's incorrect information, why perpetuate the issue if we know the correct information? Did you even read the article? Because honestly it's easier to understand the way the genes work if you learn it correctly the first time, instead of having to relearn it.
_Posted via Mobile Device_


----------



## kassierae (Jan 1, 2010)

Lol, BEP, I forget you're in Australia. I tend to not form coherent sentences when I first wake up and I'm feeding the baby 
_Posted via Mobile Device_


----------



## blue eyed pony (Jun 20, 2011)

I don't have a baby as an excuse  (nor do I want one)


----------



## Corporal (Jul 29, 2010)

I guess that I am reading this tired bc it sounded Greek to me...=b
Does this explain why my black horse bleaches red in the sun every summer?


----------



## kassierae (Jan 1, 2010)

No, lol. Some black horses just fade. Could be nutrition, lacking a mineral, or he just plain fades. My pony's had the same diet for 19 years, and some years she fades, some she doesn't
_Posted via Mobile Device_


----------



## KigerQueen (Jun 16, 2013)

after reading every post on that site in one day i feel i have a better grasp on this. and ill share this pic as it explains it best. the author was also talking about dog genetics as well.


----------



## Zexious (Aug 2, 2013)

Interesting thread and read! Thanks for sharing <3


----------



## stevenson (Sep 12, 2011)

I was told that my draft cross mare was brown, even thought she has the black points, reddish 
body , but cinnamon on her nose and flanks in summer was brown. I always called her bay.
and On black horses if they had the cinnamon muzzles and flanks that was considered brown, but now people call that fading black. So how you to know the true color without DNA test.


----------



## kassierae (Jan 1, 2010)

A fading black is just a black that fades, if it has the cinnamon points it is brown. I don't know anyone who would call a brown horse a fading black.
_Posted via Mobile Device_


----------



## SunnyDraco (Dec 8, 2011)

stevenson said:


> On black horses if they had the cinnamon muzzles and flanks that was considered brown, but now people call that fading black. So how you to know the true color without DNA test.


That isn't fading black, that is still brown. There are few exceptions to a black having cinnamon colored lighter areas like foal coats and excessive sweating (which greatly amplifies sun bleaching) as two examples that can confuse viewers about coat color. 

Seal brown will show in a test for agouti as it is an agouti mutation. The brown test itself had problems as it was inconsistent on any kind of accuracy, there was never a test for the wild bay agouti which is another mutation of agouti. 

My mom's black mare is a fading black, my sisters color tested her for agouti because they were convinced she wasn't a black because she always had a brown look to her. Results from UC Davis confirmed that she had no agouti and was heterozygous black, she just fades all year round.


----------



## Regula (Jan 23, 2012)

KigerQueen said:


> after reading every post on that site in one day i feel i have a better grasp on this. and ill share this pic as it explains it best. the author was also talking about dog genetics as well.


That image is correct for horses, but not for dogs.
The agouti in dogs is much more complex, as there are several different loci that express differently (sable, black & tan, wild color). Dogs also have two kinds of black, dominant black and recessive black, where eecessive black resembles that in horses.
_Posted via Mobile Device_


----------



## KigerQueen (Jun 16, 2013)

The author was trying to help horse people understand colors by useing horse termanology. she brakes it down first then gets alot more complex as the next image on the post showed. i just did not share it here as it was not relivent to the conversaton.


----------



## Bridgertrot (Dec 2, 2011)

DraftyAiresMum said:


> But kassie, Joe Shmoe owner doesn't WANT to know all the technicalities and lingo. They want to know in the plainest terms possible.
> 
> Also, by definition, agouti IS a modifier if it's telling the black where/how to express.
> _Posted via Mobile Device_


It doesn't have anything to do with "Joe Shmoe" not wanting to know all the lingo. It's that it's perpetuating it being taught incorrectly.

I'm actually glad to see this thread. The last handful of times I tried explaining that article and sharing it I got a bit of backlash. Good to see people coming to the dark side :rofl: for a lack of a better term. So I've been sticking to the Equine Genetics Facebook.

I actually struggled for a long time with extension and agouti. Even during my college equine genetics course I was totally lost...but was totally fine with everything else. It wasn't until after I finally figured it out. And then I saw it explained as the article shows. Then it all made sense. 

I was always hung up on "If a horse is homozygous black but looks bay then where is the red coming from?"

3 base colors. And dominant extension does not mean black. It means the ability to produce both black and red pigment.


----------



## FrostedLilly (Nov 4, 2012)

Haha, I've been keeping in the background on this too because it's still kind of hard for me to understand. The easiest way someone explained it to me is that all horses have the agouti locus, but not every horse has an allele at said locus (difference between aa and AA or Aa) and that extension (E) does not signify black, but the ability to produce black or red pigment - which depending on if the horse is recessive or dominant agouti, you will have bay (red pigment on body with black points) or black. 

It's not a modifier like cream because every horse has it (either dominant or recessive), whereas in the case of cream, not every horse will have it. Ever notice on genetic tests how agouti is either AA, Aa, or aa? It's never A/n or n/n like cream or other modifiers are?


----------



## Peppy Barrel Racing (Aug 16, 2011)

Glynnis your wording is a bit wrong. You said they won't always have an allele there. But they will always have an allele there either dominant or recessive agouti allele will be present since all horse have agouti. I think you understand it is just worded it wrong. 

Back on the main topic: Extension and agouti are a unit. All horses have extension and agouti and that will determine the base color. E is the ability to produce Red and Black pigment and e is just red pigment. It's partner agouti tells the pigment where to go it is not a modifier. A way that someone brought up to me the other day that made more sense is to think of dominant A as bay agouti and recessive a as black agouti. I like that a lot, dominant bay agouti A combined with at least one dominant E allows black pigment to be restricted to the points. Black agouti a, when combined with at least one dominant E allows black pigment to cover the entire body. 

As for the argument of teaching the wrong way vs. teaching the right way. I think the correct way should be taught from the beginning so when someone learns more about genetics they aren't confused later. As you can see many that were taught wrong had to relearn and were confused. I've been teaching new learners on Facebook just fine the correct way. People are capable of intelligence they don't need things dumbed down to an incorrect level. Teach them right the first time and be done with it.


----------



## FrostedLilly (Nov 4, 2012)

Peppy Barrel Racing said:


> Glynnis your wording is a bit wrong. You said they won't always have an allele there. But they will always have an allele there either dominant or recessive agouti allele will be present since all horse have agouti. I think you understand it is just worded it wrong.
> 
> Back on the main topic: Extension and agouti are a unit. All horses have extension and agouti and that will determine the base color. E is the ability to produce Red and Black pigment and e is just red pigment. It's partner agouti tells the pigment where to go it is not a modifier. A way that someone brought up to me the other day that made more sense is to think of dominant A as bay agouti and recessive a as black agouti. I like that a lot, dominant bay agouti A combined with at least one dominant E allows black pigment to be restricted to the points. Black agouti a, when combined with at least one dominant E allows black pigment to cover the entire body.
> 
> As for the argument of teaching the wrong way vs. teaching the right way. I think the correct way should be taught from the beginning so when someone learns more about genetics they aren't confused later. As you can see many that were taught wrong had to relearn and were confused. I've been teaching new learners on Facebook just fine the correct way. People are capable of intelligence they don't need things dumbed down to an incorrect level. Teach them right the first time and be done with it.


Woops, yes, definitely worded that wrong.  Not quite sure what I was writing there. 

I like black agouti and bay agouti - it definitely makes it easier for me to understand. As someone who was originally taught incorrectly, it's been tough for me to wrap my mind around this concept!


----------

