Dominant and recessive brown in goats

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Dominant and recessive brown in goats

Dp Sponenberg, C Lamarsh

To cite this version:

Note

Dominant and recessive brown in

_goats

DP

_Sponenberg

₁

C

LaMarsh

2

1

Virginia-Maryland Regional College of Veterinary Medicine,

Virginia Tech, Blacksburg,

VA 24061;

2

Blue

_Berry

Sunrise Farm

_{Pygmy Goats, 14453 S Macksburg Rd,}

Molalla,

OR

_97038,

USA

(Received

2

_May

1995;

accepted

18 October

₁₉₉₅₎

Summary -

Pygmy

goats in the USA occur in a

_variety

of colors

_{including black,}

roan

(called

agouti by

breeders),

and

badgerface.

In a

_minority

of animals the black areas are

replaced by

dark brown or medium brown. The colors of kids from

_matings

_among

_black,

dark-brown,

and medium-brown _goats were observed. The results are consistent with three

alleles at the Brown locus: dark brown

_(B

_d

₎

dominant to wild type

(B

+

)

which is dominant

to medium brown

_B

_b

_).

goat

/

genetics

/

coat color

_/

brown

_/

_Pygmy goat

Résumé - Bruns dominant et récessif chez la chèvre. Les chèvres

_Pygmy

des

États

Unis

_présentent

une variété de couleurs _comprenant le _noir, le rouan

_(appelé

_agouti

_par

les

_éleveurs),

et

_{« face}

de blaireau»

_(«badger

_face»).

Chez

_quelques

animaux les zones

noires sont

_remplacées

par du brun

foncé

ou du brun _moyen. On a observé des chevreaux issus de croisements entre des parents noirs, brun

_foncé

ou brun _moyen. Les résultats sont

en accord avec l’existence de trois allèles au locus Brun: le brun foncé

(N

d

)

dominant sur

le _{type sauvage}

_(B

₊

₎

lui-même dominant sur le brun _moyen

(B

b

).

chèvre

_/

_génétique

_/

couleur de robe

_/

brun

_/

chèvre _Pygmy

INTRODUCTION

Inheritance of coat color in

_goats

has received less attention than has that of

_sheep,

primarily

due to the economic

_importance

of white

_sheep’s

wool and lack of a

similar

_importance

for color in most

_goats.

Recent work

_{(Adalsteinsson}

et

_al,

₁₉₉₄₎

has documented the

_similarity

of the

genetic

control of many

goat

colors to

_sheep

colors.

include those of Asdell and Buchanan Smith

₍₁₉₂₈₎

and

_Eidregevic

_(1941),

who concluded that brown was dominant to black. This was further substantiated

_by

Hards

_(1950).

_Lauvergne

and Howell

₍₁₉₇₈₎

_postulate

that both brown and

_light

brown are recessive to

_black,

but

_segregation

data were not available for

_analysis.

Adalsteinsson et al

₍₁₉₉₄₎

conclude that

_light

_brown,

_typical

of the

_Toggenburg

breed,

is dominant to black. The

_general

conclusion one can draw from

_past

work

is that brown is dominant to

_black,

and that this brown is the

_light

brown of the

_Toggenburg

breed. Other

_types

of brown have been less well documented

_by

segregation

data.

Two

_types

of brown are

_present

in the

_Pygmy

_goat

breed in the USA. That these are eumelanic is substantiated

by

the fact that each of these browns is seen

in

_conjunction

with the

badgerface

pattern

(termed

caramel in this

_breed)

in which the browns

_replace

black in the

_typical

_pattern.

These two

_types

of brown are

distinct,

and are

_{easily recognized by}

breeders. One is a dark

brown,

and is often

called cocoa brown

_by

breeders. This is a _very dark brown. The other is a medium

brown which is much

_lighter

and

_brighter

than the dark

_brown,

and is termed red

by

breeders even

though

it is an eumelanic

phenomenon,

and not

_pheomelanic

as

are most colors termed red

_by

livestock breeders. Medium brown is more rare in the

Pygmy

breed than dark brown. The

_light

brown of the

Toggenburg

is not

_present

in the

_Pygmy

_breed,

is _very

_visually

distinct from the two browns in the

_Pygmy

breed,

and

_probably

represents

a third

_type

of brown in

_goats.

MATERIALS AND METHODS

Data from a herd of

_Pygmy

_goats

in which both dark-brown and medium-brown

goats

occurred were available for

_study.

Dark-brown

_goats

were used for several

matings,

and the

_{resulting figures}

were tested

_by

statistical

_analysis

for

_goodness

of

fit to the

_hypothesis

that dark brown is dominant to black. Medium-brown

_goats

were also used for several

_matings,

and the

_resulting

data were tested for

_goodness

of fit to the

_hypothesis

that medium brown is recessive to black.

RESULTS

The results of various crosses are

_presented

in table I. Black

_goats

mated to

black

goats

produced

over 100

kids,

none of which were dark brown. The

_mating

of black

_goats

to dark-brown

_goats

_produced

23 black and 17 dark-brown kids. These results agree with the

hypothesis

that dark brown is due to a _gene

(B

d

)

that is dominant to black

_(wild

_type,

_B

₊

_),

and that all dark-brown

_parents

are

heterozygous

(B

d

B

+

):

chi

2

=

0.9,

1

df,

P _> 0.05. The

mating

of dark-brown

_goats

to dark-brown

goats

produced

no black and seven dark-brown kids. These results

agree with the

hypothesis

that dark brown is due to a _gene

(B

d

)

that is dominant

to black

_(B

₊

_),

and that all

parental

dark-brown

goats

are

_heterozygous

(B!B!),

binomial

_test,

P = 0.13.

Medium-brown

_goats

mated to black

_goats

_produced

62 black and four medium-brown kids. These results do not

_support

the

_hypothesis

that medium brown is due to a _gene

(B

b

)

that is dominant to black

_(B

₊

_):

chi

2

=

_51,

1

If medium brown is recessive to

_black,

the black

_goats

_heterozygous

for the _gene and those not

_heterozygous

for the gene cannot be

_adequately

_separated

into two classes even

though

_they

_represent

two different

_genotypes.

Medium-brown

_goats

mated to black

_goats

which had one medium-brown

_parent

(these

being obligate

heterozygotes

under the

hypothesis

that medium brown is

_recessive)

_produced

42

black and 26 medium-brown kids. These results agree with the

hypothesis

that medium brown

_(B

_b

₎

is recessive to black

_(wild

_type

_B

₊

_),

and that the black

_goats

with a medium-brown

_parent

are

_heterozygous

(B

6

B

+

),

while medium-brown

_goats

are

_homozygous

(B

b

B

b

):

chi

2

=

3.76,

1 df,

P _> 0.05. Medium-brown

_goats

mated _to

medium-brown

_goats

_produced

28 medium-brown

_kids,

and no other

_colors,

which

is consistent with its

_being

a recessive _gene.

The

_only

occasion on which a dark-brown

_goat

with a medium-brown

_parent

was mated to a medium-brown

_goat

the kids were one dark brown and one medium

brown.

DISCUSSION

The

_homologies

and interactions of the various browns in the literature are

currently

uncertain,

although

some

_proposals

are now

possible.

The two different

_types

of brown in the

_Pygmy

_goat,

described in this

_report,

have distinct

_patterns

of inheritance. Dark brown is dominant to

_black,

and medium brown is recessive to black.

_Pygmy

_goat

owners

_rarely

cross the two distinct

_types

of

_brown,

and therefore

a

_complete

test of allelism was not

_possible

from the data. The

_{single mating}

of interest for a test of allelism was of a dark-brown

animal, carrying

medium

brown,

to a medium-brown

_goat.

The

_resulting

_kids,

one dark and one

_{medium-brown,}

are

consistent with the two

_being

allelic,

but the numbers are too few for this to be a

complete

test.

The alleles for dark brown and medium

brown, plus

a wild

_type

_allele,

can be

probably

the same as the rossa

(B

r

)

color noted in

_Lauvergne

and Howell

(1978).

The

_symbol

B

6

is

_proposed

for the recessive medium brown allele

_{(named brown),}

since this is the allele that is most

_{likely homologous}

with recessive brown in other

species.

The

_light-brown

coat color that is

_typical

of the

_Toggenburg

breed has been

assigned

to the Brown locus

_by

Adalsteinsson et al

_(1994),

with the

_symbol

BB!.

The

_symbol

should be

_changed

to

B

l

to be in

_keeping

with

_past

recommendations of COGNOSAG

_(Millar

and

Lauvergne,

1990),

as well as current COGNOSAG

(1995)

recommendations. The

_light

brown allele is dominant to wild

type.

The

_light

brown discussed in

_Lauvergne

and Howell

₍₁₉₇₈₎

could be

_homologous

with either the

_light

brown of Adalsteinsson et al

_(1994),

or the medium brown of this

_report.

The absence of

_segregation

data in

_Lauvergne

and Howell

₍₁₉₇₈₎

make it difficult

to

_assign

their

_light

brown with

_certainty.

The order of dominance within the Brown locus is

_probably

B! ? B

d

>

B

+

>

B

b

.

REFERENCES

Adalsteinsson

_{S, Sponenberg}

DP, Alexieva

_S,

Russell AJF

₍₁₉₉₄₎

Inheritance of _goat coat

colors. J Hered 85, 267-272

Asdell

_SA,

Buchanan Smith AD

₍₁₉₂₈₎

Inheritance of

_{color, beard, tassels,}

and horns in

the goat. J Hered 19, 425-430

COGNOSAG

₍₁₉₉₅₎

Revised

_guidelines

for gene nomenclature in ruminants

(1993)

Genet

Sel Evol _27, 89-93

Eidregevic

EV

₍₁₉₄₁₎

A contribution to the

problem

of

_{morphogenesis}

and evolution of

_pigmentation

in the _goat. 1’r

_Buryat-Mong

Zoovet Inst

_(Ulan-Ude)

2, 173-187

_(in

Russian);

Anim Breed Abstr 14, 237

Hards ER

₍₁₉₅₀₎

The inheritance of coat characteristics in the _goats of the British Isles.

British Goat

Society’s

Year Book 67-69

Lauvergne JJ,

Howell WE

₍₁₉₇₈₎

Un

_premier

inventaire

_g6n6tique

de la chèvre Corse. Ethnozootechnie 22, 86-88

Millar

_{P, Lauvergne}

JJ

₍₁₉₉₀₎

Loci for coat colour of goats. In: Loci

_for

Coat Colour

of

Shee