AT Bowling

DP Sponenberg

Genetics Selection Evolution

English

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Note
Champagne, a dominant color dilution
of horses
DP Sponenberg AT Bowling
1 DePartment of Biosciences and Pathobiology, Virginia-Maryland Regional College
of Veterinary Medicine, Virginia Tech, Blacksburg, VA 2l061;
2 
Veterinary Genetics Laboratory, School of Veterinary Medicine,
University of California at Davis, Davis, CA 95616-8744, USA
(Received 3 June 1996; accepted 2 July 1996)
Summary - Champagne dilution of horses results in a group of pale colors which have
mottled dusky skin and amber eyes. Body color varies from light brown to gold or cream.
Eye color of champagne foals is blue, and darkens to amber with age. The mating of
champagne to nonchampagne horses resulted in 54 champagne and 40 nonchampagne
foals. These results are consistent with a dominant gene (X2 = 2.1, 1 df, P > 0.1). This
dilution is proposed as due to the champagne allele (ChC) at the Champagne (Ch) locus.
This allele dilutes black to pale brown with dark brown points, dilutes bay to yellow with
brown points, and dilutes chestnut to gold or yellow with yellow or pale points.
horse / genetics / coat color / champagne dilution
Résumé - Champagne : un gène dominant de dilution des couleurs chez le cheval. Chez
le cheval, le phénomène de dilution des couleurs appelé « Champagne» produit un ensemble
de couleurs claires allant avec une peau noirâtre tachetée et des yeux couleur d’ambre. La
couleur du corps va de brun clair à or ou crème. La couleur de 1’oeil des poulains champagne
est bleue et s’assombrit vers l’ambre avec l’âge. Des accouplements de champagne avec des
non-champagne ont donné 54 poulains champagne et 40 non-champagne, ce qui s’accorde
avec l’hypothèse d’un gène dominant (X2 = 2, 1, p > 0, 10). Il est proposé que le gène
responsable de cette dilution soit considéré comme l’allèle champagne (Chc) au locus
Champagne (Ch). Cet allèle dilue le noir en brun clair à points bruns foncés, le bai en
jaune à points bruns, et l’alezan en or ou jaune à points jaunes ou clairs.
cheval / génétique / couleur de la robe / dilution champagne
INTRODUCTION
Dilution of color in horses is associated with several different genetic mechanisms,
and each mechanism results in a distinct group of colors (Sponenberg and Beaver,
1983). Early work confused some of these mechanisms, and attributed the actions
of two loci to a single locus (Castle and King, 1951; Castle and Singleton, 1961;
Salisbury and Britton, 1941; Singleton and Bond, 1966). The present understanding
of horse color genetics is that dilution is accomplished by three distinct genetic
mechanisms (Castle and Smith, 1953; Adalsteinsson, 1974; Van Vleck and Davitt,
1977; Adalsteinsson, 1978; Sponenberg and Beaver, 1983; Craig and Van Vleck,
1985; Lauvergne et al, 1991). This paper provides evidence of a fourth color dilution
locus for the horse.
The cremello allele at the Albino locus behaves as an incomplete dominant
(Adalsteinsson, 1974). The result of the heterozygous state is that phaeomelanin is
lightened from red to yellow, and eumelanin is unchanged. Bay is therefore diluted
to buckskin, chestnut to palomino, and black is either unchanged or diluted vary
subtly to smoky. The result of the homozygous state is that both phaeomelanin and
eumelanin are changed to cream. The skin is pink, and the eyes are blue. On any
base color the homozygous state results in cream, although subtle differences from
different base colors may persist on some horses. The cremello allele, on its own,
does not cause the distinctive striping patterns which are characteristic of another
equine dilution locus.
The dun allele at the Dun locus results in the linebacked dun group of horse
colors. It is a dominant allele, with identical appearance of heterozygous and
homozygous horses (Adalsteinsson 1974, 1978; Van Vleck and Davitt, 1977; Craig
and Van Vleck, 1985). The dun allele dilutes phaeomelanin from red to tan or light
red, and eumelanin from black to pale beige or blue. The dun allele has minimal
dilution effect on the mane, tail, and lower legs. Distinctive stripes down the back,
over the withers, and on the legs are also characteristic of the dun colors. As a result
of the dun allele, bay is changed to zebra dun, chestnut is changed to red dun, and
black is changed to grullo. The actions of dun and cremello are not additive, so that
horses with both alleles are only subtly different from those with only one or the
other. The horses with both alleles tend to retain the striping associated with dun,
and the color is diluted to the maximal extent of either the dun or the cremello
allele. Bay is changed to light gold or yellow zebra dun, chestnut to linebacked
palomino, and black to grullo. Horses that are homozygous for cremello and also
have dun are usually cream colored with striping typical of duns.
The silver dapple allele at the Silver Dapple locus is a third genetic mechanism
for dilution of horse color (Castle and Smith, 1953). The silver dapple allele is
dominant, and heterozygous and homozygous horses are similar. Phaeomelanin is
not conspicuously changed. Eumelanin is diluted to pale sepia. The dilution is
greatest in mane, tail, and lower leg. The result on black is silver dapple, the classic
form of which is a dappled sepia with very pale mane, tail and lower leg. The
action of the silver dapple allele is variable, though, and sometimes its presence is
associated with only minimal dilution of eumelanin. Bay is changed to red silver,
which retains the red body of bays but has typical changes associated with the
silver dapple allele in the mane, tail and legs. Chestnut is changed minimally, if
at all, because chestnut phenotypes are phaeomelanic, and the silver dapple allele
therefore can have no action.
A group of horse colors that is distinct from the three previous dilute color groups
consists of horses with amber eyes (which are blue a birth and then darken) and
light colors all of which tend to have a bright metallic sheen. Horses with these
colors are sometimes born a dark color, which then lightens with age. This is the
reverse of most colors of horses (Sponenberg and Beaver, 1983), and contributes to
the confusion surrounding these colors. The skin of these horses is dusky pink with
dark mottling. This skin color is darker than that of the skin of horses homozygous
for cremello and is lighter than the skin of horses with dark color or with dilute
color from the other three genetic mechanisms. The colors of this group lack the
striping typical of dun horses. This group of colors occurs in a number of breeds as
a rare variant.
One of the colors within this group of dilute colors is metallic light brown with
darker brown mane and tail, which is the color called champagne by Tennessee
Walking Horse breeders. In the past this color has been registered as buckskin
or chestnut, probably for lack of a suitable alternative designation by registration
authorities. The champagne color does not fit the definition of either buckskin or
chestnut. A second variant within the group has a yellow body and brown mane,
tail, and lower legs. This variant is frequently registered as buckskin despite the
brown (rather than black) mane, tail and legs and the eye and skin characteristics
typical of the champagne group of colors. A third variant has a gold or yellow body
and legs, and light gold or flaxen mane and tail. This color is frequently registered
as palomino although these horses have the amber eyes and mottled dusky pink skin
associated with the champagne color group, unlike the palominos arising from the
cremello allele. In addition to their occurrence in the Tennesse Walking Horse, these
colors have been noticed in Spanish Mustangs and ponies of uncertain breeding. The
group of colors including champagne was studied in order to document their mode
of inheritance.
MATERIALS AND METHODS
The complete results of mating individual champagne dilute stallions and mares
were available, and are presented in table I. These included several Tennessee
Walking Horses, and one Spanish Mustang. The matings were all to nondilute
mates. The production records of other individual horses with the champagne allele
were studied to determine the colors resulting from the presence of the champagne
allele with various background color genotypes. This included horses for which
complete records were not available, and these records are presented in tables II
and III.
RESULTS AND DISCUSSION
The matings from champagne dilute horses for which complete data were available
produced 54 champagne and 40 nonchampagne foals. Under the hypothesis that
the champagne allele is dominant, X = 2.1, 1 df, P > 0.1. This allele is proposed
as the champagne allele at the Champagne locus.
All horses that produced brown foals with brown points (the champagne color)
also produced black foals, indicating that they had genotypes capable of producing
black foals. The champagne color was never produced by horses who failed to
produce black foals. The mating of champagne horses to black mates produced
six champagne and five black foals. These findings are consistent with champagne
color being the result of the champagne allele on an otherwise black background.

Horses with gold body color and yellow or white manes and tails consistently
reproduced this color or chestnut following mating to chestnut mates. This is
consistent with the gold color resulting from the action of the champagne allele
on an otherwise chestnut background.
Horses with yellow body color and brown points only were produced by matings
that could also produce bay genotypes, and it is likely that the yellow with brown
points color results from the action of the champagne allele on an otherwise bay
background.
In some instances horses with gold bodies and light manes and tails were mated
to palomino mates. Some of the resulting foals were ivory or cream colored, with
mottled dusky skin and dark bluish green eyes. One such ivory foal was mated to
a chestnut mare and reproduced the ivory color. The ivory color is probably the
result of the heterozygous condition fo both the champagne and the cremello alleles.
If this is true, then these two dilutions are additive. Extensive breeding tests have
not yet been accomplished, but the reproduction of the ivory color from a chestnut
mare indicates that the two alleles are not at the same locus, since they appear to
be segregating independently.
Instances in which two champagne-colored horses were mated to one another
were relatively rare, and only occurred with horses for which complete production
records were unavailable. As a result, the color of homozygotes is undocumented.
In all cases of champagne-to-champagne matings, the specific color mated together
was the gold type with pale points. These matings produced 15 foals, all of which
were gold. The consistent production of the gold color suggests that the homozygous
condition of the champagne allele does not result in more extensive dilution than
does the heterozygous condition, which argues against an interpretation of the
champagne allele as an incomplete dominant. The lack of nondilute horses from
these matings is an indication that perhaps not all foals are reported. If this is the
case, then extensively diluted foals may well have not been reported.
The champagne allele is dominant, and dilutes both phaeomelanin and eume-
lanin. Eumelanin is diluted most on the body, and less on the legs, mane, and tail.
Phaeomelanin is diluted to yellow or gold. The result of champagne on a black back-
ground is the original champagne color, which is a pale brown horse with darker
brown mane, tail, and legs. This is the most widely recognized of the group, mostly
because it is difficult to confuse this color with any other horse color. The result of
champagne on a bay background is yellow with brown mane, tail and legs. These
horses are frequently registered as buckskin, although the usual definition of buck-
skin describes those horses whose color arises from the cremello allele, and which
have black manes, tails and legs, and dark skin, with yellow body color. The result
of champagne on chestnut is a golden body and mane and tail which are either a
similar gold color or nearly white. This gold color is easy to confuse with the usual
palomino arising from the cremello allele, although the skin and eye characteristics
are distinct. The results of combining the champagne allele with other base colors
are less certain, but the effect of champagne on palomino is probably ivory, which
retains the skin and eye characteristics of the champagne group but is otherwise
similar to creams that are homozygous for cremello.
ACKNOWLEDGMENTS
The authors gratefully acknowledge the valuable work and interest of B Kincade, L Nutter,
S Batteatte and L Howland; and their sharing of data for this report.
REFERENCES
Adalsteinsson S (1974) Inheritance of the palomino color in Icelandic horses. J Hered 65,
15-20
Adalsteinsson S (1978) Inheritance of yellow dun and blue dun in the Icelandic toelter
horse. J Hered 69, 146-148
Castle WE, King FL (1951) New evidence on the genetics of the palomino horse. J Hered
42, 60-64
Castle WE, Singleton WR (1961) The palomino horse. Genetics 46, 1143-1150
Castle WE, Smith FH (1953) Silver dapple, a unique color variety among Shetland ponies.
J Hered 44, 139-146
Craig L, Van Vleck LD (1985) Evidence for inheritance of red dun dilution in the horse.
J Hered 76, 138-139
Lauvergne JJ, Silvestrelli M, Langlois B, Renieri C, Poirel D, Antaldi GGV (1991) A new
scheme for describing horse coat colour. Livest Prod Sci 27, 219-229
Salisbury GW, Britton JM (1941) The inheritance of equine color: II. The dilutes, with
special reference to the palomino. J Hered 32, 255-260
Singleton WR, Bond QC (1966) An allele necessary for dilute coat color in horses. J Hered
57, 74-77
Sponenberg DP, Beaver BV (1983) Horse Color. Texas A&M University Press, College
Station, TX
Van Vleck LD, Davitt M (1977) Confirmation of a gene for dominant dilution of horse
colors. J Hered 68, 280-282
