JB wow! That is a huge difference from 3 month to late summer! What is the coat like now?
So if it is recessive, they would need to be homozygous to display it? Similar to the red gene?
It’s amazing isn’t it?!
This was him on July 8 of this year, roughly the same time of year as that “3 months after that” pic from last year. He doesn’t look much different now, maybe a bit more faded.
Just for fun, this is him (showing his butt) playing with another brown horse, but one who looks more bay-like this time of year, and whose Winter coat is a good bit darker.
That 2nd horse in that pic looked like this in April of this year, pretty much shed out, and a lighter color already but not from bleaching, just a difference between a Winter and Summer coat
For a comparison, here’s a picture of a black (left), bay (middle) and the above brown horse (right) mid-May a few years ago
Oh, about the homozygous/recessive stuff:
To be brown, no, you don’t have to be homozygous. Agouti (responsible for bay and brown and wild bay) affects the distribution of black pigment. There are 4 forms of it:
- a, meaning “not there”
- A, for bay
- At, for brown
- A+, for wild bay, not yet testable, but thought to be dominant to bay.
We DO know that bay is dominant to brown, that’s a known fact.
This means to be bay, you first have to be black-based, and you can be either
- AA - homozygous for bay
- AAt - 1 copy each of bay and brown, and since bay is dominant, the horse is bay, or
- Aa - 1 copy of bay and 1 copy of “nothing”
To be brown, you’re firstly black-based, and then:
- Ata - 1 copy each of brown and “nothing”
- AtAt - homozygous brown
A brown horse cannot be AAt, or he’d be bay
The chestnut horse is homozygous for the recessive form because it’s in the spot that determines the base color - black or red. It’s recessive to black, so a heterozygous black horse - Ee - will be black-based, and it takes the homozygous recessive form ee to be red-based. Then, since Agouti doesn’t affect red-based horse (as it only affects black pigment) it can be any variation above and the horse is still chestnut (assuming no other modifiers)
Thank you for the education JB!
So here is a picture of the tobiano, whose color reminds me of the fillies. This is at it’s darkest, and I’m fairly certain based on all that has been said - brown. This is how the filly is in person, but with some more sunbleaching.
Yep, most definitely brown. Lovely picture!
[QUOTE=RacetrackReject;6507971]
No idea on color, but plese put her in a fedex box and mail her to Texas. Thank you. =)[/QUOTE]
That’s right. At which time I will snag her from your doorstep.
Watch your back RTR!
Adorable foal! A friends Pablo foal was that color when it was little and shedded out to be dark bay.
