Equine Reproduction

1
Equine Reproduction

• LACP
• Chapter 6, pages 157-165

2
Equine Breeding Data

• Type of estrous cycle
• Seasonally polyestrous (long day breeder)
• Age of female at puberty
• 10 to 24 months
• Age of male at puberty
• 10 to 24 months
• Time of first breeding
• Varies (2 to 3 years)
• Estrus cycle frequency
• 15 to 26 days (21d)
• Duration of Estrus
• 2 to 12 days (Average 4 to 7)

3
Equine Breeding Data (contd)

• Time of ovulation
• Last 48 hours of estrus
• Optimal time of breeding
• Every 24 to 48 hours while the mare is in heat
• Gestation period for light breeds
• 335 to 340 days
• Birth weight
• Varies by breed
• Litter size
• One (twins are rare and undesirable)
• Weaning age
• 4 to 7 months

4
Selecting a Mare and Stallion

• Mare

• Stallion

• Physical characteristics
• Temperament
• Athletic potential
• Evaluate previous foals, reproductive ability

• The four Ps
• Phenotype
• Performance
• Pedigree- proves parentage not quality
• Progeny

5
Breeding Soundness Examination

• Used on both males and females
• Usually performed near the beginning of the
  breeding season.
• A physical exam must be performed first

6
Male Evaluation Female Evaluation

• Rectal palpation
• Ultrasound exam of the ovaries, uterus, and
  cervix
• Visual exam of the vagina and cervix
• Uterine culture
• Possibly a endometrial biopsy

• Penis
• Prepuce/sheath
• Scrotum
• Testicles
• Semen analysis
• Venereal disease
• Physical exam

7
Puberty of the Male

• This is the age when a male can impregnate a
  female.
• 10 24 months of ages
• Castration or Gelding

8
Males in General for Breeding purpose

• Most males must be restrained for the breeding
  examination.
• Approach with CAUTION!
• Never turn your back on a stallion.
• Most males tend to resent handling of the genital
  areas.
• Consistency!- same handlers, same routine, same
  equipement for breeding , train to collect/breed
  properly (should start with first breeding)
• Do not associate breeding with pain

9
Preputial and Penile Cleaning Routine care of
the penis is a must in all male horses,
regardless of castration. Smegma is a combination
of secretions from sebaceous glands, sweat
glands, dead cells, and dirt.
10
Keep in mind that Houston gets hot-hot-hot!
11
Three masses of smegma beans. These beans can
become the size of walnuts.
12
Beans are bad!

• The beans can compress the tip of the urethra and
  make urination difficult and very painful.

13
Sheath Cleaning

• Gloves should be worn.
• Extract the penis manually or with the aid of
  tranquilization.
• One hand holds the penis, the other actually does
  the cleaning with warm water, mild soap and
  cotton or gauze.
• Antibacterial ointment can be applied to lesions
  if found.

14
Stallion Physiology
Onset of sexual maturity 10-24 mo (18)
Life span of sperm in female tract 2-4 days
Survival time with fertilizing capacity 1-2 days
Sperm output
Semen volume/ejaculate 20-100 ml
Sperm concentration X 106 30-800 ml
sperm/ejaculate X 109 6
15
Sperm Production

• Sperm Output and Production is influenced by
• Season
• Testicular size
• Age
• Frequency of ejaculation
• Behavior

16
Number of Sperm Depends On

• Seasonal Influences (Photoperiod)
• Effected Areas
• Ejaculate volume
• Sperm numbers
• Total sperm/ejaculate
• Sperm motility
• Willingness to breed
• Mounts before breeding
• Scrotal size
• Testosterone production

17
Semen Collection

• Quality and quantity of sperm
• Evaluate diseases of the male reproductive tract
• AIartificial insemination

18
Semen Collection and Storage

• Artificial vagina collection most common
• Avoid contact with air, sunlight, and extreme
  heat and cold
• Fresh
• Use within 24 hours
• Frozen
• 0.5-ml straws
• 500 million progressively motile sperm per
  insemination

19
Breeding phantom (Phantom) for semen collection.
Can be adjusted to a comfortable height for the
stallion
20
After mounting the mare the artificial vagina is
introduced to The stallion for ejaculation
collection.
21
AVArtificial vagina Optimal temperature inside
the AV is approximately 113F (48C)
22
Colorado Style
Missouri
23
French INRA model
Roanoke model
24

• http//video.google.com/videoplay?docid2375536614
  971713657eintI-SrarDpj0qAPFvP2WCgqstallionsem
  encollectionhlen
• http//www.youtube.com/watch?vySUq0xHIBig

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General Semen Analysis

• Appearance
• Volume
• Concentration of sperm
• Number of sperm
• Sperm morphology
• Live sperm
• Sperm motility
• pH (7.2-7.5)

26
Artificial Insemination

• Inseminate pipette into the uterus
• Multiple inseminations 24 to 48 hours apart
• Common to use ultrasound to monitor follicular
  growth

27
Extenders

• Milk based liquid- contains sugars, electrolytes
  and antibiotics
• Protection, prolonged sperm survival, optimal pH
  and osmotic pressure, protection against cold
  shock.

28

• Hormones- testosterone and estogen
• Leydig cells of the testes produce testosterone
  under the influence of LH (pituitary)
• Sertoli cells produce estrogen under influence of
  FSH (pituitary) - not well understood
  regulation and secretion of other hormones nurse
  cells
• Testosterone necessary for spermatozoa production

29
Female Reproductive System

• Mares are seasonally polyestrous, meaning that
  during the breeding season they cycle repeatedly.
• The natural breeding season centers around the
  period of long day length-light!
• January 1st is the designated birth date for all
  horses in the northern hemisphere. This means
  that a horse born in January and a horse born in
  June will both be considered 1 yr old the
  following January. Welcome to the horse world!

CTVT pg. 381
30
Mare Anatomy

• Vulva
• Vagina
• Cervix
• Uterus
• Oviducts
• Ovaries

Left Ovary
Vagina
Cervix
Oviduct
Left Uterine Horn
Uterine Body
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Female Reproductive System

• Cost-effectively mares are tricked into
  perceiving that the days are lengthening by
  providing artificial lighting and mimicking a 16
  hour daylight period.
• This can be done either indoor or outdoor. This
  should be done in the evening and not the morning.

CTVT pg. 381
33
Reproductive Physiology of the Mare

• Estrus Cycle 15-26 days (21)
• Estrus 4-7 days
• Ovulation last 48 hrs. of estrus
• Gestation 11 months (330-345 days)
• light breeds (305-365 days)

LACP pg. 157
34
Mares Cycle
Percent
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Mare Reproductive Physiology

• FSH- follicular recruitment
• LH- follicular maturation (with low
  progesterone), or aids in production of estrogen,
  ovulation, luteinization of CL
• Estrogen- released from growing follicle,
  initiates standing heat, relax cervix and vulva,
  increases smooth muscle contraction, negative
  feedback on FSH, positive on LH

37
Mare Reproductive Physiology

• Progesterone- secreated from CL, tightens cervix,
  readies uterus for pregnancy, decreased
  receptivity to stallion, decreases smooth muscle
  contraction, negative feedback on LH
• PGF2a shortens CL life span

38
Photoperiod Effect

• Reproductive activity in spring is stimulated by
  an increasing photoperiod
• 16 hrs daylight per day
• 30-60 days
• Mechanism
• Alteration of hormone secretion by the pineal
  gland and hypothalamus

39
Hormonal Manipulation

• Administer PGF2a to shorten life of CL (Lutalyse,
  Estrumate, Equimate)
• Estrus will be 2-4 days later (lasts 4-7days),
  breed at 7-12 days
• Progesterone administration- maintains a
  long-term estrus suppression, maintain pregnancy,
  suppresses LH and blocks ovulation
• When taken off 4-7 days to estrus, 7-12d to
  breed (Regumate)

40
Transition

• 1-3 waves of follicles develop regress
• Estrogens produced by developing follicles
• Irregular/prolonged estrus exhibited
• 1 follicle eventually ovulates
• Thereafter, mares ovulate at 21-day intervals

41
Prediction of Ovulation

• Number of days in heat
• Growth rate of largest follicle
• Average 3-5 mm/day
• Size of largest follicle
• Softness of preovulatory follicle
• Ultrasound image

42
Signs of Estrus

• Most consistent
• Elevated tail raise
• Winking
• Other supporting signs
• Leaning
• Squatting
• Standing still
• Urinating

43
Equine Breeding

• Successful breeding and pregnancy in female
  horses is not often easy to accomplish.
• Mares do not readily accept the male.
• Timing must correspond to ovulation.
• Mares usually breed and conceive in the spring
  and summer with deliver about 11 months later in
  the spring or early summer.
• Video..

LACP pg. 281
44
Pregnancy Diagnosis

• Rectal palpation
• Diagnostic Ultrasound, per rectum
• Diagnostic Ultrasound, Transabdominal
• External Palpation
• Abdominal Radiographs
• Laboratory Tests

45
Preparation of the Perineum/vulva

• Both areas should be cleansed so that you do not
  contaminate the vagina, cervix and uterus with
  fecal material and other debris.
• Tail should be wrapped or bandaged.

LACP pg. 282
46
Cleaning

• You can use a mild soap, povidone-iodine scrub,
  or a chlorhexidine scrub with warm water and
  rolled cotton.
• Clean the anal area first removing all fecal
  material. Scrub the lips of the vulva and
  gradually working a circular fashion, include the
  perineum, anus, and inner aspect of the buttocks.
  Repeat the process until cotton shows no evidence
  of residue.

47
A vaginal speculum examination being performed on
a mare using a disposable speculum.
48
A uterine biopsy instrument being inserted
through the vagina and cervix into the uterus.
49
Diagnostic Ultrasound
An ultrasound image of the black appearance of
multiple follicles on an equine ovary.
50
An ultrasound image of a 14-day pregnancy in an
equine uterus. This method can detect a fetus as
early as 10 days old and is more reliable than
rectal palpations. video
51
Diagnostic Ultrasound
Twin embryos at 12 days. The equine uterus is not
designed to support and nourish more than one
fetus competition for space and nutrition
usually results in the death and abortion or
stillbirth of both twin fetuses.
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Twins

• Occasionally, one twin may be born alive but is
  typically weak and small, and it faces a high
  mortality rate.
• Birth of living twins is rare, and survival of
  both is even rarer. When twin embryos or fetuses
  are detected, the vet needs to advise the owner
  of options to either terminate the pregnancy or
  to terminate only one of the embryos in hope that
  the other may survive.

53
Rectal Palpation

• Most common, rapid method
• As early as 18 days post ovulation
• Increase uterine tone, presence of vesicular bulge

54
External Palpation

• External abdominal palpation as used in small
  animals is not possible in large animals.
• You place both fists against the lower flank area
  on the mare and rapidly press inward this
  displaces the pregnant uterus (if present) and
  rebounds back into the original position by
  bumping against your fists. This method lacks
  accuracy and is not typically done.

55
Abdominal Radiographs

• Not useful for large animals, but commonly used
  in small animals.

56
Wee-Foal-CheckerUrine pregnancy test for mares
57
Laboratory Tests

• Used when rectal exams are inconclusive or
  impossible to perform.
• Can be difficult to interpret and have limited
  usefulness. You usually can only perform these
  during the later stages of pregnancy.
• Progesterone assay- (16-24d) nonspecific, high
  values may mean functional CL
• Estrogen- (60-100d) higher then during estrus

58
Natural Breeding vs. Artificial Insemination
ADVANTAGES
DISADVANTAGES

• More efficient use of semen
• Reduce transmission of diseases from stallion to
  mare
• Reduce risk of breeding injuries in mare

• Success of AI requires greater knowledge and
  skill
• Increased cost
• Greater risk of human injury during collections

59
Embryo Transfer, Why?

• Foals from older, injured, or sub fertile mares
• Access to wider gene pool
• Increase production and profit on genetically
  superior mare

• Get embryo from mares who foal late in season
• Foals from 2 year old mares
• Foals form mares in competition

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Embryo Transfer, why not?

• Expensive
• Need trained personell
• Embryo recovery can be low
• Lack of commercially available embryo

• Lack of interest by many registries
• Many breed organization do not accept
• Harder to superovulate

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Embryo Transfer

• Synchronization of donor and recipient mare
• Embryo flushing
• Embryo transfer procedure

62
PGF2? Lutalayse or Estrumate

• Shorten the interval between estrous periods
• Treatment of a maintained corpus luteum
• After foal heat
• Estrous synchronization with prostaglandins

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Embryo Transfer

• Ultrasound or palpation for follicular
  development
• Prepare donor mare
• Induce ovulation
• Flush 7 to 9 days after ovulation
• Embryos collected in filter cup
• Viewed
• Transferred within 12 to 24 hours

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Recipient Mare

• Good health and BCS
• Easy to handle
• Similar in body size to donor
• 4-10 years old
• Sound breeding condition
• Responsive to teaser
• Regular cycling
• cheap

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