Download Equine Reproduction and Genetics

Equine Reproduction
and Genetics
Equine Science 2
A. Heat Detection is Key to any
Breeding
1. The ability to determine when the mare
is ready to be bred is important for the
success of any equine reproduction
management system.
a. Conception rates are highest when mares
are bred 1 -2 days before ovulation.
b. Therefore, the best time to breed occurs 24
to 48 hours before the end of estrus.
B. Key to Detecting Estrus
1. The key signal of estrus is the receptivity of
the mare to a stallion.
a. To determine if a mare is in heat and is receptive to
a stallion, one can tease a mare with a stallion to
observe specific behaviors.
b. A handler, or some form of barrier, partition, or
restraint is used to ensure the mare and stallion
remain separated while behaviors are observed.
B. Key to Detecting Estrus
2. Keep accurate records for each mare for
each teasing secession or teasing
program will not be effective.
a. A numbered scoring system is often used,
where 0=the mare rejects the stallion and
4= the mare shows intense interest in the
stallion.
C. Ways of Teasing a Mare to
Detect Estrus
1. Group teasing is used when a large
number of mares need to be observed.
a. A stallion is placed in a central pen
surrounded by connected and adjoining
pens where several mare can be placed to
allow the equine limited contact.
1) Sometimes called a teasing mill.
2) required a minimum amount of handling.
C. Ways of Teasing a Mare to
Detect Estrus
a) Disadvantages is the shy mares may not
approach the stallion to exhibit behaviors and
dominant mares may hinder shy mares.
b. Mares must be given a minimum of 15 -20
minutes to show signs.
2. Individual teasing is used when one
mare is teased by the teasing stallion.
a. A teasing rail is used to keep a single mare
and stallion apart while behavior is observed
C. Ways of Teasing a Mare to
Detect Estrus
b. The teasing rail should be a solid partition of
about 4’ high to avoid injury to the mare or
stallion.
D. Behaviors exhibited by a mare
in standing heat:
1.
2.
3.
4.
5.
6.
Flexing the pelvis.
Raising her tail.
Frequent urination.
Spreading her hind legs.
Contracting and relaxing the vulva.
Allowing the stallion to nip and chew on her flanks and
neck.
7. A mare the shows intense interest will practice
winking, where she raises her tail, urinates, and
exposes the clitoris as she assumes the mating
position.
E. Reasons for Manipulating
Estrus
1. Mares are seasonally polyestrous, that is, a)
2.
the go into heat several times a year, but b)
they usually go into heat during specific
seasons of the year.
Most mares do not cycle naturally in the
winter.
a. Spring-type conditions of increased daylight,
warmer temperatures and improved nutrition from
better quality of forage have a indirect affect on the
pituitary gland.
E. Reasons for Manipulating
Estrus
a. The result is that the pituitary gland secretes FSH
(Follicle Stimulating Hormone) and LH
(Lutenizing Hormone) which are essential for the
estrus cycle.
3. The two major reasons for rearranging
the heat cycles of the mare are:
a. For the convenience of the owner for showing
and racing.
b. Higher reproductive efficiency.
E. Reasons for Manipulating Estrus
4. Race and show equine ages are based on the
calendar year. Therefore, they need to be bred
earlier than the natural breeding period for
equine.
a. The common birthday for race and show horses is
considered January 1st.
b. Foals born closer to January 1st will be older relative
to foals born later in the year and should have an
advantage over other individuals in their age
division.
E. Reasons for Manipulating Estrus
c. Rather than breeding in March or April as
usual, these animals need to be bred in
early February.
F. Two most common techniques used
to manipulate estrus
1. Environmental stimulation is the simplest and
most effective technique used.
a. Extending day length to 16 hours of light with
artificial lights has worked best.
b. A 200-watt incandescent bulb or 2 40-watt
florescent bulbs hung at a height from 7’ to 8’
provides adequate light in the average stall.
c. Artificial light increases shedding.
d. Increased heat and improved nutrition are part of
the increased lighting program.
F. Two most common techniques used
to manipulate estrus.
b. Three hormones have been used in conjunction to
manipulate estrus:
1) Prostaglandin is the most widely used and has been used
to induce estrus and control the lifespan of the corpus
luteum. (mares must be cycling to work)
2) HCG (Human Chorionic Gondotropin) is the most common
gondotropin hormone and has been used to control
ovulation.
3) Progesterone and synthetic progestin such as “Regumate”
are steroid hormones that keep mares out of estrus.
F. Two most common techniques used
to manipulate estrus.
2. Chemical hormone control has been used
to stimulate cycling and control
ovulation.
a. Chemical control requires the
synchronization of ovulation and estrus and
works best when used along with rectal
palpation and reproductive ultrasonography.
A. Care of the mare.
1. Classifications of mares affect the kind of
management decisions.
a. Maiden mares have never been bred nor had a
foal. A maiden mare may be frightened or reject
her foal when it tries to nurse.
1) Rubbing some of her milk on the foal helps her
identify the foal as hers.
2) Avoid touching the foal, the mare and foal
identifies one another by smell, the dam and
the foal must bond or the foal may become
attached to humans.
A. Care of the mare.
b. A barren mare is one that
is not pregnant, but was
bred in the previous or
current season.
1) Indicates there was a failure
in conception or in
maintaining pregnancy.
A. Care of the mare.
c. An open mare is
one that was not
pregnant and not
bred in the
previous or current
season.
d. Pregnant mare will
foal in the current or
following season
A. Care of the mare.
2) Management involves discovering if there is a
problem and correction it.
3) Uterine infections are a major cause of infertility
and is most often caused by pnuemovagina,
(windsucking), as a result of poor breeding
conformation.
4) Age and poor nutrition may also contribute to
breeding problems.
A. Care of the mare.
e. Wet mares are nursing a foal and need a
ration to supply energy and protein for
lactation.
1) Energy needed increases by about 45%, but is
helped if the mare is in proper body condition.
2) Protein needed for lactation increases by
almost 65% and is often more limited.
A. Care for the mare.
2.
Importance's of proper
body condition
a.
Body condition scoring
is an excellent
management tool.
1)
Numbers 1-9 are used
to indicate the amount
of body fat on an
equine with higher
scores meaning the
animal is carrying more
body fat.
A. Care for the mare.
2) Mares should score
between a 5.5 and
7.5 on body
condition; some fat
is deposited along
the withers, behind
the shoulders,
around the tail head
and ribs cannot be
scene but felt with
some fat in
between.
A. Care for the mare.
b. The second
trimester is the best
time to help a mare
get in the correct
body condition if
she is not already
there.
1) Feed .4 to .6 pounds
of grain per 100
pounds of body
weight and
supplement with hay
if pasture is poor.
A. Care for the mare.
3. Pregnancy checking is important for all bred
mares in the fall to ensure mare have
maintained pregnancy, even though they
were checked in the spring breeding season.
Pregnancy checking can be accomplished
by:
a. Palpation or using one hands to feel the form,
size, position and consistency of the uterus.
(usually done by veterinarians and trained horse
people)
A. Care for the mare.
1) A mare must be 28 to 30 days into gestation
(pregnancy) before palpation can be used to
diagnose pregnancy.
2) Is one of the quickest and most efficient
methods of diagnosing pregnancy.
A. Care for the mare.
b. Ultrasonography uses an ultrasound probe
inserted into the equine’s rectum and
moved across the reproductive tract to
produce sound waves the either reflect
from or propagate through various tissue
materials to produce an image that
determines and monitors pregnancy.
1) Ultrasonography is very accurate, can diagnose
pregnancy as early as 14 days, and is very
useful in determining the length of pregnancy.
A. Care for the mare.
2) Ultrasonography can determine the sex of the
animal between 60 to 70 days of the gestation
period.
3) . Ultrasound can diagnose reproductive
problems in nonpregnant mares
A. Care for the mare.
c. Blood test to determine changes in
hormone level can give an indication of the
stage of pregnancy.
1) The presence and levels of ECG (Equine
Chorionic Gonadotrophin) in the mares blood
between 40 and 130 days of gestation indicate
the mare has “settled” and high levels of
estrogen sulfate (a form of estrogen) indicate a
live embryo or fetus.
A. Care for the mare.
4. Feeding management means meeting the
mare’s maintenance requirements for the first
8 months of gestation. If the mare is in
correct body condition.
a. It is important to say consistent, that is do not let
her loose or gain weight.
b. She probably will not need grain if pasture is
adequate, but should have ample clean, fresh
water and trace mineralized salt provided free
choice.
A. Care for the mare.
5. Health care includes dental,
hoof, deworming, and
scheduled vaccinations.
a. Do no give unnecessary drugs
during the first 60 days and the last
30 days of pregnancy.
b. Vaccinations are common for
rinopneumonitis, influenza, tetanus,
equine encephalomyelitis.
A. Care for the mare.
6. Preparing for foaling
a. While broodmares do not need shoes, if they are
shod, shoes need to be removed prior to foaling to
protect the foal at birth.
b. The mare should be moved where she is going to
foal 30 days prior to foaling so that she may
produce protective antibodies for the environment
to be included in colostrum.
1) The foal has to obtain antibodies against infection from
colostrum.
A. Care for the mare.
2) Foal’s intestines will absorb antibodies only
during the first 24 hours after birth.
c. The best prediction of foaling time is past
foaling history and knowledge of gestation
lengths.
1) Normal gestation period is 342 days plus or
minus 20 days.
2) Signs will vary but may include signs of
restlessness and sweating.
3) Wax beads (drops of colostrum) appear on the
teats 3-4 days prior to foaling.
A. Care for the mare.
7. Foaling should occur in a clean place where
the mare and foal can bond without
unnecessary interruptions. If in a small
paddock, no other horses should be around.
a. In a normal birth presentation, the foal’s front feet
(one slightly in front of the other) appear first with
the heals down toward the mare’s hock. The foal’s
nose should be lying on or about the knees.
A. Care for the mare.
b. If foaling is in a stall, the preferred bedding is
wheat, rye, or barley straw since shavings and
sawdust cling to afterbirth and may lead to
infections.
c. In the absence of dystocia (difficult foaling) due
to abnormal presentation position, twinning, or
other birthing problems, the foal and mare
should be monitored but allowed to bond
without human contact.
A. Care for the mare.
d. Foaling occurs in three stages:
1) Mare may be restless a few minutes to 24
hours prior to her water breaking.
2) Hard labor should last from 20 to 30 minutes, if
the foal’s front feet and head are not seen
within 5 to 10 minutes of the onset of hard
labor, the mare should be gotten up and walked
until a veterinarian arrives.
3) The uterus shrinks and the placenta (afterbirth)
is expelled within 2 to 3 hrs of birth or a medical
emergency exist that requires a veterinarians
assistance.
A. Care for the mare.
8.
Post foaling management includes:
a. Close monitoring for the first 48 to 72 hours.
b. Allowing the foal and mare out in the paddock for
exercise the day after birth, weather permitting, to
assist the mare in uterine discharge and return to
normal.
c. Looking for signs of a swollen, feverish, udder that
indicate the foal is not nursing.
d. Providing the mare with slightly warm water, some
form of wet-bran mash, and alfalfa hay to give a
slightly laxative affect to assist and comfort her in
defecating.
A. Care for the mare.
9. Foal heat occurs 3-12 days after foaling and
sometimes an attempt is made to breed
mares during this short estrus cycle.
a. Conception rate is only 40% and increased risks
are present.
b. The advantage is that the next years foaling date
is moved up when the mare successfully carries a
foal consummated during foal heat.
B. Care of the stallion.
1. The number of
mares a stallion will
settle (breed
successfully)
depends largely on
the age of the
stallion and the
mating system
used.
B. Care of the stallion.
Age of stallion
Average number of
mares settled when
hand mated is used
Average number of
mares settled when
pasture mating is used
Two year old
10
5
Three year old 30
15
Mature
stallions
25
50
YEARLINGS SHOULD NOT BE DEPENDED ON
FOR BREEDING PROGRAM
B. Care of the stallion.
b. Breeding stallions should
be fed like an equine at
hard work
1) Approximately 1.5
pounds of grain and 1
pound of hay per 100
pounds of body weight.
2) Grazing good grass, if
only for short time
periods, is
recommended
B. Care of the stallion.
c. Fencing should be
tall and strong
particularly when
mares are in
adjoining pastures,
unless pasture
mating is on a ready
serve basis.
d. Regular exercise
usually results in
increased sexual
vigor and fertility.
A. Newborn foal care.
1. First, make sure the foal is breathing
properly by cleaning the mucous out
of its nostrils. This can be done by
carefully placing the thumb and
forefinger along the top of the
nostrils towards the muzzle.
2. Make sure there are no objects in
the foals mouth that might choke it.
A. Newborn foal care.
3. If the umbilical cord does not break
in birthing and there is no danger to
the foal, wait 10 to 15 minutes after
birth to break it.
The extra time allows about 30% of the
foals blood to flow from the mare.
b. NEVER cut the umbilical cord,
because a clean cut causes excessive
bleeding.
a.
A. Newborn foal care.
c.
Procedures for breaking the umbilical
cord:
1)
2)
3)
4)
Find the narrowing of the umbilical cord
located about 2 inches from the foals
abdomen.
Place the cord over the first and second
fingers with narrow area between them.
Press down with thumb until cord breaks.
NEVER pull against the foals abdomen.
A. Newborn foal care.
4. The naval stump needs to be
treated soon after birth with a 2%
iodine or 50-50 mixture of 7% iodine
and glycerine to prevent infection
and neonatal septicemia.
The glycerine causes the iodine to
stick to the naval stump.
b. Apply iodine 2 to 3 times a day during
the first day at 6 to 8 hour intervals.
a.
A. Newborn foal care.
5. If the mare has
not had a tetanus
immunization
before foaling,
give the foal a
tetanus antitoxin
injection.
A. New born foal care.
6. The foal must nurse within 2 to 3 hours
after birth, and the foal must obtain an
adequate amount of colostrum during its
first 12 hours of life to supply antibodies.
a.
b.
There is no placental transfer of antibodies
from the mare to the foal during pregnancy,
Foals rely on passive transfer of immunity
from colostrum to protect them from disease.
A. Newborn foal care.
7. Many newborn
foals are
constipated and
should be treated
with a 4-ounce
Fleet phosphate
enema available
from drug stores.
B. Foal observation.
1. Observe the foal
especially during
the first 48 to 72
hours after birth.
a.
b.
A normal foal should
be active when
awake.
A healthy foal will
normally sleep on
their side.
B. Foal observation
2. Foals should nurse as often as seven
times a hour during their first week, and
gradually decline to where they only
nurse once per hour by seven weeks of
age.
a.
b.
A mare with a full, hot, or leaking udder is an
indication the foal has not nursed and a sure
sign that the foal is sick.
A foal that is nursing, but not gaining weight
may not be getting adequate milk as a result
of the mare’s eating endophyte-infected
fescue pasture
C. Weaning
1. Weaning normally occurs at 4 to 6
months and is a stressful time for the foal
and dam.
a.
b.
Reduce stress by separating with a fence that
allows the dam and foal to see, smell, and
hear each other.
Separation for increased lengths of time also
works well to prevent stress. The foal may
nurse 3 times the first day, 2 times the second
day, once in the third day, and completely
separated the fourth day.
C. Weaning
2. Foals who are eating creep feed
suffer less at weaning. Creep feed
for foals must contain 16-18 percent
protein, 0.8 percent calcium, and
0.55 percent phosphorus. The
calorie to protein ratio should be 5550 grams of protein per Mcal.
C. Weaning
3. Delay worming, vaccinations and
halter training until 3-4 weeks after
training.
A. Pasture Mating is the Least
Managed System of Breeding
1.
2.
Mares and stallions
are allowed in the
same pasture.
Stallions breed any
mare in heat.
B. Hand mating

1.
2.
Hand mating is a system of breeding where a handler
restrains the mare to prevent injury to the stallion while
allowing the stallion to pursue the breeding process.
Most expensive horses are hand mated.
Mares that are selected for hand mating are
supposed to be in heat.
C. Artificial Insemination

Artificial Insemination (A.I) is a system of breeding
where semen is collected from a stallion is
deposited into the uterus of a mare without
copulation.
1.
Semen is collected in an artificial vagina from a
stallion that mounts a mare or phantom mare.
A catheter is placed into the uterus of the mare in
heat and a syringe is used to transfer the collected
semen through the catheter.
2.
D. Embryo Transfer

1.
Embryo Transfer is the non-surgical removal
of an embryo from the uterus of one mare
and inserting it into the uterus of another
mare.
The recipient mare contributes nothing to the
genetics of the foal.
D. Embryo Transfer
Consists of three phases:
2.
1)
2)
3)
Synchronization of the donor and recipient mares so that
ovulation occurs in both within a 12 hour time period is
done with hormone therapy
Flushing the embryo in a sterile solution 7 to 8 days after
insemination
Transferring the embryo in a nurturing solution through a
uterine transfer catheter ( an extra recipient mare is
usually used to insure use of the best synchronization.
A. Pasture mating
1. Advantages of pasture mating:
a. Pasture mating is convenient to
the equine owner because very
little labor and management are
required.
b. Pasture mating catches mares
shy about breeding.
c. Pasture mating results in a high
“settle percentage” ( a high
conception rate among mares
that are bred)
A. Pasture Mating
2. Disadvantages of pasture
mating:
a. A lower number of mares can be
serviced by the stallion.
b. Breeding dates are hard to
determine.
c. There is some risk to injury to
the stallion in pasture mating.
(Stallions shown for conformation
cannot safely be pasture mated)
B. Hand Mating
1. Advantages of hand mating
a. Hand mating prevents injury to
the stallion during the breeding
process.
b. Breeding sanitation is preformed
by the handler which protects
both the mare and the stallion.
B. Hand Mating
2. Disadvantages of hand mating:
a. The settling percentage is not as
high as pasture mating.
b. Hand mating requires additional
labor to have a handler present
during the breeding process.
C. Artificial
Insemination (A.I)
1. Advantages of artificial
insemination
a. Venereal disease control is possible by
diluting collected semen with
antibodies prior to depositing in the
mare.
b. Chances of injury to handler and
equine are less than with other mating
systems.
c. Overuse of the stallion is less likely
since one collection of semen may be
enough to breed several mares.
C. Artificial
Insemination (A.I)
d. Semen is evaluated for quality at
periodic intervals during the use
of A.I.
2. Disadvantages of Artificial
Insemination
a. A higher number of mares fail to
settle or conceive than with
pasture mating.
b. A.I. requires trained personnel to
collect and deposit semen at the
appropriate time for conception.
c. A.I. is labor intensive.
D. Embryo Transfer
1. Advantages of Embryo
Transfer
a. Increased production of foals
from genetically superior mares.
b. Reproduction from older, less
fertile mares that are great
mares.
c. Reproduction by 2-yr old mares.
d. Allows a valuable sport donor
mare to reproduce without
incurring term of pregnancy.
D. Embryo Transfer
2. Disadvantages
of Embryo
Transfer
a. Very
expensive.
b. Yield is low.
A. Genetics

The study of heredity and variation.
A. Genetics
Heredity- is the resemblance among
individuals that is passed on, or capable of
being passed on, genetically from parents
to offspring.
1.
a.
Genes are the basic unit of inheritance and are
passed to the next generation in gamete (sex
cell) formation on chromosomes.
A. Genetics
b.
c.
d.
Different forms of the same gene at the same
location on the chromosome are called alleles.
Genes are made of DNA (deoxyribonucleic
acid) in specific sequence (DNA sequence) that
gives an organism its own unique traits.
Genes are carried on chromosomes and must
occur in distinct pairs for normal body growth
and development.
A. Genetics
e.
Chromosomes also occur in distinct pairs and
are consistent in number for a species of horse
having 64 chromosomes (32 distinct pairs) and
donkeys having 62 chromosomes or 31 distinct
pairs to make up their genome (complete set of
chromosomes)
A. Genetics
Variation is the occurrence of differences
among individuals of the same species due
to genetic variation.
2.
Chromosomes and gene numbers change
during gamete (sex cell) formation:
a.
1)
First, the 32 chromosome pairs of a cell duplicate,
then one of the four members associated with the
duplicated pairs is randomly transferred to one of
the four forming gametes.
A. Genetics
2)
3)
4)
The random transfer of chromosomes and their
genes to forming gametes is the major cause of
genetic differences among related individuals.
The newly formed gamete now contains only one
member of each original chromosome pair.
When egg and sperm unite at fertilization, the
chromosome number is restored to its original
value.
A. Genetics
The new cell formed is the zygote that develops
into a fetus.
b.
1)
2)
The zygote has one member of each chromosome
pair from its sire and the other member from its
dam.
The resulting offspring is genetically different from
either parent, but carries genetic traits of both.
B. Genetics and traits
The genetic make-up (specific genes that
reside in the gene pairs which control a
trait) is the animal’s genotype.
1.
a.
Each cell contains a duplicate set of genes
derived from the single gene sets received at
conception by both the mother and father.
B. Genetics and traits
b.
The duplicate genes
(alleles) are similar but
not necessarily
identical. For example,
while both sets of
genes are for hair
structure, one set may
be for straight hair and
the other be curly hair.
B. Genetics and traits
2.
Both sets of genes function simultaneously
in the cell. If the pair has identical genes, it
is a homozygous gene pair. If the gene pair
has different genes, the gene pair is a
heterozygous gene pair.
B. Genetics and traits
If the gene pair is heterozygous, one allele may
be dominant and the other recessive. Dominant
does not mean better, but that the allele is
expressed when placed in relationship with the
recessive allele.
a.
1)
2)
the dominant allele of a gene is expressed with a
capital letter such as A,B,C,D…..W,X,Y,Z
The recessive allele of a gene is expressed as a
lower case letter such as a,b,c,d,…w,x,y,z.
B. Genetics and traits
b.
Very few economically
important traits are
controlled by one or
few gene pairs, but
rather possibly
hundreds of gene
pairs.
B. Genetics and traits
There are two categories of traits:
3.
Qualitative traits are:
a.
1)
2)
3)
Controlled by one or very few gene pairs that can
be easily identified
Little impacted by the environment
Easily broken into distinct categories that look the
same.
B. Genetics and traits
Quantitative traits are controlled by hundreds or
thousands of gene pairs.
b.
1)
2)
3)
The environment does affect the expression of the
gene pairs controlling quantitative traits.
Most economically important traits are quantitative
traits.
Phenotypes of quantitative traits are not able to be
classified into distinct categories.
B. Genetics and traits
4.
Regardless of whether the traits are
quantitative or qualitative, the individual’s
phenotype (what we can see) is the sum of
effects of the genotypic and the
environmental effects.
B. Genetics and traits
5.
Influence of Genetics and Environment on Certain Traits in
Equine
Trait
Due to Genetics%
Due to
Environment-%
Height at Withers
40 to 50
50 to 55
Body Weight
25 to 30
70 to 75
Body Length
30 to 40
60 to 65
Heart Girth Circumference
20 to 25
75 to 80
Pulling Power
20 to 30
70 to 80
Walking Speed
40 to 45
55 to 60
Movement
40 to 50
50 to 60
Temperament
25 to 30
70 to 75
Reproductive Traits
10 to 15
85 to 90
A. Genetics and Sex
Determination
Chromosomes determine the sex of an equine.
1.
a.
b.
2.
Females carry XX chromosomes and every egg
possesses one X chromosome.
Males carry XY chromosomes and half the sperm carry
the X chromosome and the other half carries the Y
chromosome.
When the eggs and sperm unite, half the zygotes
will be female (XX) and the other half will be male
(XY).
B. Genetics and Color
1.
Genetic determination
of coat color is based
on the presence of
alleles or different
forms of each gene
that determines coat
color.
B. Genetics and Color
Dominant alleles are represented by a capital
letter. They are never hidden by their related
recessive alleles.
a.
1.
2.
When present, W (white) or G (grey) gene alleles
will hide other coat-color genes.
You cannot determine by looking at an animal if the
second allele is dominant or recessive.
B. Genetics and Color
Recessive alleles are represented by a lower
case letter. Hidden recessive genes are hidden
by a dominant allele.
b.
1)
Recessive genes can only by expressed if both of
the pair are the same. For example, recessive
genes such as ww will always be expressed as
nonwhite, gg will always be nongrey.
B. Genetics and Color
2.
Coat Color Classification
Based on the Effects of
the Alleles of Seven
Genes (see handout)
C. Mules and Hinnies
Mules are a genetic abnormality in that they have
an uneven number of chromosomes. (63
chromosomes)
1.
a.
b.
c.
d.
Sire is a male donkey (jack) which has 62 chromosomes
(31 pairs).
Dam is a female horse (mare) which has 64
chromosomes (32 pairs).
The mule has the features of a horse in size and body
shape, but has a shorter, thicker head with long ears and
the braying voice of a donkey.
Mules are usually infertile.
C. Mules and Hinnies
The hinny or jennet is the reverse cross
between a stallion and a female donkey.
2.
a.
b.
Similar to the mule in appearance, but smaller
and more horse like, with shorter ears and a
longer head
Hinnies are more difficult to produce than
mules, and rarely will a female mule or hinny
come into heat and produce a foal.
A. Steps in defining coat
color
1.
Determine if G or W alleles are present.
If they are present, the process stops.
They mask other colors.
2. If neither G or W alleles are present,
look for black hair either on the points
or distributed over the body. If yes,
then the EE or Ee allele is present. If
the hair is red, then the ee allele is
present.
B. Genetic Formulas and Resulting Coat
Colors
Genetic Formula
Color
W
White
G
Gray
E, A, CC, dd, gg, ww, toto
Bay
E, aa, CC, dd, gg, ww, toto
Black
ee, aa, CC, dd, gg, ww, toto
Red
E, A, CCer, dd, gg, ww, toto
Buckskin
ee, CCer, dd, gg, ww, toto
Palomino
CerCer
Cremello
E, A, CC, dd, gg, ww, TO
Bay Tobiano
ee, CC, D, gg, ww, TO
Red Dun Tobiano