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Laura Behning
75 Glass Spring Rd.
Covington, GA 30014
770-385-1240
morgans@mindspring.com
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This is probably the hardest part of color genetics to understand. Once you understand this, the rest is easy!
All horses- regardless of what additional color genes they may have- are either RED or BLACK (red is chestnut)
at their base color.
Everything else that you see- and consider a different color- is actually the result of additional modifying genes
added to the base color of RED or BLACK. They change the appearance, or phenotype, of the horse- but the horse is still RED or BLACK. RED and BLACK are called BASE COLORS.
Black (which is written as "E", "E" meaning the Extension locus, which is
the place on the horse's genetic code where base color is determined) is dominant to
Red (which is written as "e"); chestnut/red is recessive to black. This means that if a horse has at least one one black gene, it will be black (or a black based color), and it needs TWO red genes (thus no black gene at all) to be red (or any red based color).
In other words, black "covers" red.
Our first and most common modifier is Agouti, the "bay gene".
BAY and BROWN are actually a modification of BLACK. In other words, bays and browns are black horses with a dominant modifying gene- called AGOUTI- added.
Agouti acts to restrict the black of the black horse to just the points- in other words, the mane, tail and lower legs.
This allows the red that is "uncovered" by agouti to show through on the body of
the horse- in varying degrees depending on the type of Agouti present. Chestnuts can carry agouti, but it won't show on them as they have no black hair to restrict to the points. They can, of course, pass it on to their offspring. Black horses cannot have agouti, because if they did, they'd be bay and not black. For example, a black X chestnut cross might produce a bay foal; this happened because the agouti, or bay gene, actually came from the chestnut parent, and the black base color came from the black parent.
It is theorized that there are three different types of agouti. "A" is the Agouti which causes "regular" bay; "A+" is the "wild type" Agouti, which results in a light bay horse with very little black on the legs, usually just around the fetlocks; and "At" is brown, or what is sometimes called "seal brown", a nearly black horse with reddish areas on the muzzle and flanks. A horse will have some combination of the three types, one of the three types p lus one non-agouti gene (one non-agouti gene is written as "a"), or have no agouti at all ("aa"). |
Evidence suggests that there is an order
of dominance amongst the various agoutis, with wild bay (the most restrictive of black) being dominant to bay,
and bay being dominant to brown (the least restrictive of black). If this is
true, two browns could not produce a bay. Also, if a horse has one bay and one wild bay gene, he'll be
wild bay; if he has one brown and one bay he'll be bay; but he'll need two brown genes or one brown, one "no agouti" (a) to be brown at all.
There is a lot of crossover in phenotype (appearance) between very dark bays and browns. At this time there is no way to distinguish which of the three types of agoutis a horse has when color testing.
The difference between the two may just be a matter of shade, just as other colors have a vast range of shades from very light to very dark.
There is artwork depicting a medium shade of each color on each page of our Color Gallery. Be aware that the possible shades in each color may vary (lighter or darker) than what you see in the artwork; the photos used will illustrate those variations in shade. Also, keep in mind that the bay base horse will always be on the left, the chestnut based horse in the middle, and the black based horse on the right. This will help you remember what base color is "underneath" the various dilution genes and modifiers
shown on this website.
Click on any picture to enlarge
BOBCAT'S WONDERFUL TONITE (Denlore's Desert Storm X Courtland Charisma), 2004 dark bay
or brown mare (left) with her owner Catherine LaBarre and
COURTLAND CHARISMA (UVM Elite X Disco Dolly),
1990 brown mare with Bob Armstrong. "Tootsie" was thought to be black, but Agouti
testing showed her to have one Agouti gene- which, taken with her very dark phenotype, means she is actually a seal brown.
Black horses cannot have Agouti or they will be modified to bay or brown. Many brown horses
are mistaken for blacks, and often Agouti testing is the only way to sort them
out. Photo by Denlore Photography.
OKAN STORM KING (Meredith Billirubin X Good News Priscilla), 1997
brown stallion owned by Don & Mary Curtis, Okan Morgans.
At the present time there is no way to distinguish dark bay from brown via testing. The difference between the two may just be a matter of shade, just as
other colors have a vast range of shades from very light to very dark. Photo by Tim O'Neal.
AMADEUS MOZART ARA-LI (Jake Mint X Amadeus Nekomia Ash), 1995 black stallion owned
by Ara-Li Acres, New
Brunswick, Canada. Mozart is hitched to an 1890 New Brunswick
carriage built in Port Elgin. The driver and horse owner is Dawn Brown, and
the passenger is Lynn Wells, whose grandfather built the carriage. Both
women are friends from Collina, NB, just west of Sussex. They are seen in
front of the stagecoach house once operated by Hugh McMonagle of Sussex
Vale. This business was the half-way stop for travelers going between Saint
John and Moncton. Mr. McMonagle was a prominent local businessman, sportsman
and politician in the mid-1800s who introduced the Morgan Horse to New
Brunswick. Mozart is a full Lippitt Morgan. (Vanessa Packman photo)
MTN TOP WHIPPOORWILL TANEK (Whippoorwill Talisman X Spring Lake Katefly), 2005 black colt owned by Kristal Khomoki of Mtn Top Morgans, PA. Black foals can be born any shade from an inky all over black to a more silver gray as here- or even lighter.
TELISHAN REJOICE (Telishan Santiam X LCS Fine Crystal), 1999 dark bay mare with her 2005 black colt
CASTLERIDGE ABOVE, by Above Command. "Joy" is so dark that she might be called brown by some people. This "gray area" in defining dark bay vs. brown has led some registries (for example, the Jockey Club) to simply list "dark bay/brown" as a color choice on their registration applications.
Joy is owned by Melody Faber of Telishan Morgans, GA and "Abe" is owned by Debi Boies, Castleridge Farm, SC.
TASHOTA'S WARRIOR (Serendipity Storm B X Cambridge Velvetrose), 1984 brown stallion owned by Marilyn Esteb, Stone Pine Farm. Photo by Laura Behning.
WINDEN MY WINGS (Shanghai X Essex Aria), 2005 bay colt owned by Jeanine
Key. "Wings" shows that not all bay foals have a starkly black mane and tail; his is a mix of gray, black and brown hairs and with his still-light lower legs, he might be mistaken for a chestnut foal. Chestnut foals, however, generally have a self colored mane and tail in some shade of red like the body. Bay foals' legs shed to black at the foal shed; darker bay and brown foals are born with quite a bit of black already on their legs.
All foals can have quite a bit of light hair in the tail. This grows out as the foal matures. Photo by Tami Johnson, Windenhill Morgans.
GAB CREEK TRAVELER (Funquest Erick x Gab Creek Gay Mashanta), 2004 chestnut stallion owned by
Bill and Susan Visi. Pictured as a two year old. Photo by Laura Behning.
The late ANDA'S BALLERINA (O-At-Ka Carl Marshal x Princess Pierette) 1969 chestnut mare pictured at age 36. This grand old mare
was a lifetime friend and partner for her owner Sue Colby of Macushla Morgans in NH. She has competed in Hunt Seat, Western and Carriage Driving, done extensive trail riding, parades and weddings. She also
produced three foals: the bay gelding Macushla Squire Dan (by Medomak Cavalier) who still competes, including over fences, with his young rider; the chestnut mare Macushla Cashmere (by Serenity March Time) who was Sue's Combined Driving horse; and the bay mare Macushla Brenna (by Medomak Sea Splendor), also owned by Sue.
SCATTERED OAKS BOLDVENTUR (Venturous Colonel X New Heritage Laura Knight) is a full Lippitt chestnut stallion, foaled in 2000, and owned by Lisa Algarin, Claywood Farm, SC.
CBMF RUBY (GLB Bell Pepper X Cy Don's Libby), 2000 chestnut mare owned by Paula Reny of ME.
MERWIN ALL A BREEZE (Mr. Breezy Cobra X Merwin's Adonna),
1976 black chestnut stallion (deceased). This horse shows the darkest shade of chestnut- so dark it could be
mistaken for black. A close examination of the hair around the fetlocks would reveal a few reddish
or silver hairs, a clue that this is not a black horse. All chestnut foals are born some shade of red, and it is only after they shed the foal
coat that their true shade of chestnut begins to become apparent. Photo courtesy of Sandra Nichols.
  
All three photos are of the 1998 wild bay gelding
BLYTHEWOOD BEAU BRUMMEL (Equinox Beaubrook X Coreen Ashmore), owned by Pat Thrasher and bred by Kathy Newcomb,
Blythewood Morgans. Beau is particularly interesting
because his washed out points, including the mixed silver-gray mane and tail, make him a very good mimic of a silver dapple bay.
His sire is a brown, so cannot be hiding a silver dapple gene; his dam is flaxen chestnut, and while silver dapple does not "show" on
chestnuts, she is from the very prolific breeding program of Frances Bryant, based on Jubilee King and Lippitt lines. If silver dapple
was "hiding" in the chestnuts from these lines (and many similarly bred horses have been bred by the Quietude Stud, as well), it is
likely we'd have seen it by now. Photos courtesy of Kathy Newcomb.
BUSH CREEK TRILLIUM (Mainframe, chestnut X FCF Escapade, bay), 2005
wild bay filly owned by Janie Denning. This filly's sire appears to be carrying at least one wild bay gene. We know this because
"Trilly's" dam is a bay, and if she had a wild bay gene,
she'd be wild bay instead of "regular" bay (because wild bay is thought to be dominant to all the other agouti genes). Another
wild bay by Mainframe can be seen here, the 2005 colt, Warlock's Eminent Domain.
Despite the fact that wild bay is the
most dominant of the agoutis, it is fairly unusual in our Morgan gene pool. If you have a wild bay Morgan,
we'd love to feature it on this site! Email Laura Behning with your picture(s). Photo courtesy of Doug Sluiter.
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