Equine ReproductionEquine Reproduction

LACP LACP

Chapter 6, pages 157-165Chapter 6, pages 157-165

Equine Breeding DataEquine Breeding Data

Type of estrous cycleType of estrous cycle Seasonally polyestrous (long day breeder)Seasonally polyestrous (long day breeder)

Age of female at puberty Age of female at puberty 10 to 24 months 10 to 24 months

Age of male at puberty Age of male at puberty 10 to 24 months10 to 24 months

Time of first breeding Time of first breeding Varies (2 to 3 years)Varies (2 to 3 years)

Estrus cycle frequency Estrus cycle frequency 15 to 26 days (21d)15 to 26 days (21d)

Duration of Estrus Duration of Estrus 2 to 12 days (Average 4 to 7)2 to 12 days (Average 4 to 7)

Equine Breeding Data (cont’d)Equine Breeding Data (cont’d)

Time of ovulationTime of ovulation Last 48 hours of estrusLast 48 hours of estrus

Optimal time of breedingOptimal time of breeding Every 24 to 48 hours while the mare is in heatEvery 24 to 48 hours while the mare is in heat

Gestation period for light breedsGestation period for light breeds 335 to 340 days335 to 340 days

Birth weightBirth weight Varies by breedVaries by breed

Litter sizeLitter size One (twins are rare and undesirable)One (twins are rare and undesirable)

Weaning ageWeaning age 4 to 7 months4 to 7 months

Selecting a Mare and StallionSelecting a Mare and Stallion

MareMarePhysical Physical

characteristicscharacteristicsTemperamentTemperamentAthletic potential Athletic potential Evaluate previous Evaluate previous

foals, reproductive foals, reproductive abilityability

StallionStallionThe four “P’s”The four “P’s”PhenotypePhenotypePerformancePerformancePedigree- proves Pedigree- proves

parentage not parentage not qualityquality

ProgenyProgeny

Breeding Soundness ExaminationBreeding Soundness Examination

Used on both males and femalesUsed on both males and femalesUsually performed near the beginning of Usually performed near the beginning of

the breeding season.the breeding season.A physical exam must be performed firstA physical exam must be performed first

Male Evaluation Female EvaluationMale Evaluation Female Evaluation

PenisPenis Prepuce/sheathPrepuce/sheath ScrotumScrotum TesticlesTesticles Semen analysisSemen analysis Venereal diseaseVenereal disease Physical examPhysical exam

Rectal palpationRectal palpation Ultrasound exam of the Ultrasound exam of the

ovaries, uterus, and cervixovaries, uterus, and cervix Visual exam of the vagina Visual exam of the vagina

and cervixand cervix Uterine cultureUterine culture Possibly a endometrial Possibly a endometrial

biopsybiopsy

Puberty of the MalePuberty of the Male

This is the age when a male can This is the age when a male can impregnate a female.impregnate a female.

10 – 24 months of ages10 – 24 months of agesCastration or Gelding …Castration or Gelding …

Males in General for Breeding Males in General for Breeding purpose purpose

Most males must be restrained for the breeding Most males must be restrained for the breeding examination. examination.

Approach with CAUTION!Approach with CAUTION! Never turn your back on a stallion.Never turn your back on a stallion. Most males tend to resent handling of the genital Most males tend to resent handling of the genital

areas.areas. Consistency!- same handlers, same routine, same Consistency!- same handlers, same routine, same

equipement for breeding , train to collect/breed equipement for breeding , train to collect/breed properly (should start with first breeding)properly (should start with first breeding)

Do not associate breeding with painDo not associate breeding with pain

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.

Keep in mind that Houston gets Keep in mind that Houston gets hot-hot-hot!hot-hot-hot!

Three masses of smegma “beans”. These Three masses of smegma “beans”. These beans can become the size of walnuts.beans can become the size of walnuts.

Beans are bad!Beans are bad!

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

Sheath CleaningSheath Cleaning Gloves should be worn.Gloves should be worn. Extract the penis manually or Extract the penis manually or

with the aid of tranquilization.with the aid of tranquilization. One hand holds the penis, the One hand holds the penis, the

other actually does the cleaning other actually does the cleaning with warm water, mild soap and with warm water, mild soap and cotton or gauze.cotton or gauze.

Antibacterial ointment can be Antibacterial ointment can be applied to lesions if found.applied to lesions if found.

Stallion PhysiologyStallion 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

Sperm ProductionSperm Production Sperm Output and Sperm Output and

Production is Production is influenced by:influenced by: SeasonSeason Testicular sizeTesticular size AgeAge Frequency of Frequency of

ejaculationejaculation BehaviorBehavior

Number of Sperm Depends On:Number of Sperm Depends On:

Seasonal Influences (Photoperiod)Seasonal Influences (Photoperiod) Effected AreasEffected Areas

Ejaculate volumeEjaculate volume Sperm numbersSperm numbers Total sperm/ejaculateTotal sperm/ejaculate Sperm motilitySperm motility Willingness to breedWillingness to breed Mounts before breedingMounts before breeding Scrotal sizeScrotal size Testosterone productionTestosterone production

Semen CollectionSemen Collection

Quality and quantity of spermQuality and quantity of spermEvaluate diseases of the male Evaluate diseases of the male

reproductive tractreproductive tractAI=artificial inseminationAI=artificial insemination

Semen Collection and StorageSemen Collection and Storage

Artificial vagina collection most commonArtificial vagina collection most common Avoid contact with air, sunlight, and Avoid contact with air, sunlight, and

extreme heat and cold extreme heat and cold FreshFresh

Use within 24 hoursUse within 24 hours FrozenFrozen

0.5-ml straws0.5-ml straws500 million progressively motile sperm per 500 million progressively motile sperm per

inseminationinsemination

Breeding phantom (Phantom) for semen collection. Can be adjustedto a comfortable height for the stallion

After mounting the mare the artificial vagina is introduced to The stallion for ejaculation collection.

AV=Artificial vaginaOptimal temperature inside the AV is

approximately 113°F (48°C)

Colorado Style

Missouri

French INRA model

Roanoke model

http://video.google.com/videoplay?docid=2375536614971713657&ei=ntI-SrarDpj0qAPFvP2WCg&q=stallion+semen+collection&hl=en

http://www.youtube.com/watch?v=ySUq0xHIBig

General Semen AnalysisGeneral Semen Analysis

AppearanceAppearanceVolumeVolumeConcentration of spermConcentration of spermNumber of spermNumber of spermSperm morphologySperm morphologyLive sperm %Live sperm %Sperm motilitySperm motilitypH (7.2-7.5)pH (7.2-7.5)

Artificial InseminationArtificial Insemination Inseminate pipette into the uterusInseminate pipette into the uterusMultiple inseminations 24 to 48 hours Multiple inseminations 24 to 48 hours

apart apart Common to use ultrasound to monitor Common to use ultrasound to monitor

follicular growthfollicular growth

ExtendersExtenders

Milk based liquid- contains sugars, Milk based liquid- contains sugars, electrolytes and antibioticselectrolytes and antibiotics

Protection, prolonged sperm survival, Protection, prolonged sperm survival, optimal pH and osmotic pressure, optimal pH and osmotic pressure, protection against cold shock. protection against cold shock.

Hormones- testosterone and estogenHormones- testosterone and estogen Leydig cells of the testes produce testosterone Leydig cells of the testes produce testosterone

under the influence of LH (pituitary) under the influence of LH (pituitary) Sertoli cells produce estrogen under influence Sertoli cells produce estrogen under influence

of FSH (pituitary) - not well understood – of FSH (pituitary) - not well understood – regulation and secretion of other hormones regulation and secretion of other hormones “nurse cells”“nurse cells”

Testosterone necessary for spermatozoa Testosterone necessary for spermatozoa productionproduction

Female Reproductive SystemFemale Reproductive System

Mares are seasonally polyestrous, meaning that Mares are seasonally polyestrous, meaning that during the breeding season they cycle repeatedly.during the breeding season they cycle repeatedly.

The natural breeding season centers around the The natural breeding season centers around the period of long day length-light!period of long day length-light!

January 1January 1stst is the designated birth date for all is the designated birth date for all horses in the northern hemisphere. This means horses in the northern hemisphere. This means that a horse born in January and a horse born in that a horse born in January and a horse born in June will both be considered 1 yr old the following June will both be considered 1 yr old the following January. Welcome to the horse world!January. Welcome to the horse world!

CTVT pg. 381

Mare AnatomyMare Anatomy

VulvaVulvaVaginaVaginaCervixCervixUterusUterusOviductsOviductsOvariesOvaries

Left Ovary

Oviduct

Left UterineHorn

Uterine Body

CervixVagina

Female Reproductive SystemFemale Reproductive System

Cost-effectively mares are tricked into Cost-effectively mares are tricked into perceiving that the days are lengthening by perceiving that the days are lengthening by providing artificial lighting and mimicking a providing artificial lighting and mimicking a 16 hour daylight period.16 hour daylight period.

This can be done either indoor or outdoor. This can be done either indoor or outdoor. This should be done in the evening and not This should be done in the evening and not the morning.the morning.

CTVT pg. 381

Reproductive Physiology of the MareReproductive Physiology of the Mare

Estrus Cycle: 15-26 days (21)Estrus Cycle: 15-26 days (21)Estrus: 4-7 daysEstrus: 4-7 daysOvulation: last 48 hrs. of estrusOvulation: last 48 hrs. of estrusGestation: 11 months (330-345 days)Gestation: 11 months (330-345 days)

light breeds (305-365 days)light breeds (305-365 days)

LACP pg. 157

Mares Cycle

0

20

40

60

80

100

120

J F M A M J J A S O N D

% Mares ovulating % Mares in estrus

Perc

ent

Mare Reproductive PhysiologyMare Reproductive Physiology

FSH- follicular recruitmentFSH- follicular recruitmentLH- follicular maturation (with low LH- follicular maturation (with low

progesterone), or aids in production of progesterone), or aids in production of estrogen, ovulation, luteinization of CLestrogen, ovulation, luteinization of CL

Estrogen- released from growing follicle, Estrogen- released from growing follicle, initiates standing heat, relax cervix and initiates standing heat, relax cervix and vulva, increases smooth muscle vulva, increases smooth muscle contraction, negative feedback on FSH, contraction, negative feedback on FSH, positive on LHpositive on LH

Mare Reproductive PhysiologyMare Reproductive Physiology

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

PGF2PGF2αα – shortens CL life span – shortens CL life span

Photoperiod EffectPhotoperiod Effect

Reproductive activity in Reproductive activity in spring is stimulated by an spring is stimulated by an increasing photoperiodincreasing photoperiod

16 hrs daylight per day16 hrs daylight per day 30-60 days30-60 days Mechanism Mechanism

Alteration of hormone Alteration of hormone secretion by the pineal secretion by the pineal gland and hypothalamusgland and hypothalamus

Hormonal ManipulationHormonal Manipulation

Administer PGF2Administer PGF2αα to shorten life of CL to shorten life of CL (Lutalyse, Estrumate, Equimate)(Lutalyse, Estrumate, Equimate)

Estrus will be 2-4 days later (lasts 4-7days), Estrus will be 2-4 days later (lasts 4-7days), breed at 7-12 daysbreed at 7-12 days

Progesterone administration- maintains a long-Progesterone administration- maintains a long-term estrus suppression, maintain pregnancy, term estrus suppression, maintain pregnancy, suppresses LH and blocks ovulationsuppresses LH and blocks ovulation

When taken off 4-7 days to estrus, 7-12d to When taken off 4-7 days to estrus, 7-12d to breed (Regumate)breed (Regumate)

TransitionTransition

1-3 waves of follicles 1-3 waves of follicles develop & regressdevelop & regress

Estrogens produced by Estrogens produced by developing folliclesdeveloping follicles

Irregular/prolonged Irregular/prolonged estrus exhibitedestrus exhibited

1 follicle eventually 1 follicle eventually ovulatesovulates

Thereafter, mares Thereafter, mares ovulate at ~21-day ovulate at ~21-day intervalsintervals

Prediction of OvulationPrediction of Ovulation

Number of days in heatNumber of days in heatGrowth rate of largest Growth rate of largest

folliclefollicleAverage 3-5 mm/dayAverage 3-5 mm/day

Size of largest follicle Size of largest follicle Softness of preovulatory Softness of preovulatory

folliclefollicleUltrasound imageUltrasound image

Signs of EstrusSigns of Estrus

Most consistentMost consistentElevated tail raiseElevated tail raiseWinkingWinking

Other supporting signsOther supporting signsLeaningLeaningSquattingSquattingStanding stillStanding stillUrinatingUrinating

Equine BreedingEquine Breeding

Successful breeding and Successful breeding and pregnancy in female horses is pregnancy in female horses is not often easy to accomplish.not often easy to accomplish.

Mares do not readily accept Mares do not readily accept the male.the male.

Timing must correspond to Timing must correspond to ovulation.ovulation.

Mares usually breed and Mares usually breed and conceive in the spring and conceive in the spring and summer with deliver about 11 summer with deliver about 11 months later in the spring or months later in the spring or early summer.early summer.

Video..Video..

LACP pg. 281

Pregnancy DiagnosisPregnancy Diagnosis

Rectal palpationRectal palpationDiagnostic Ultrasound, per rectumDiagnostic Ultrasound, per rectumDiagnostic Ultrasound, TransabdominalDiagnostic Ultrasound, TransabdominalExternal PalpationExternal PalpationAbdominal RadiographsAbdominal RadiographsLaboratory TestsLaboratory Tests

Preparation of the Perineum/vulvaPreparation of the Perineum/vulva

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

Tail should be wrapped Tail should be wrapped or bandaged.or bandaged.

LACP pg. 282

Cleaning Cleaning You can use a mild soap, You can use a mild soap,

povidone-iodine scrub, or a povidone-iodine scrub, or a chlorhexidine scrub with warm chlorhexidine scrub with warm water and rolled cotton.water and rolled cotton.

Clean the anal area first Clean the anal area first removing all fecal material. removing all fecal material. Scrub the lips of the vulva and Scrub the lips of the vulva and gradually working a circular gradually working a circular fashion, include the perineum, fashion, include the perineum, anus, and inner aspect of the anus, and inner aspect of the buttocks. Repeat the process buttocks. Repeat the process until cotton shows no until cotton shows no evidence of residue.evidence of residue.

A vaginal speculum examination being A vaginal speculum examination being performed on a mare using a disposable performed on a mare using a disposable

speculum.speculum.

A uterine biopsy instrument being inserted A uterine biopsy instrument being inserted through the vagina and cervix into the through the vagina and cervix into the

uterus.uterus.

Diagnostic Diagnostic UltrasoundUltrasound

An ultrasound image of the black appearance of multiple follicles on an

equine ovary.

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

Diagnostic UltrasoundDiagnostic 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.

TwinsTwinsOccasionally, one twin may be born alive Occasionally, one twin may be born alive

but is typically weak and small, and it but is typically weak and small, and it faces a high mortality rate.faces a high mortality rate.

Birth of living twins is rare, and survival of Birth of living twins is rare, and survival of both is even rarer. When twin embryos or both is even rarer. When twin embryos or fetuses are detected, the vet needs to fetuses are detected, the vet needs to advise the owner of options to either advise the owner of options to either terminate the pregnancy or to terminate terminate the pregnancy or to terminate only one of the embryos in hope that the only one of the embryos in hope that the other may survive.other may survive.

RECTAL PALPATION RECTAL PALPATION

Most common, rapid methodMost common, rapid method

As early as 18 days post ovulationAs early as 18 days post ovulation

Increase uterine tone, presence of vesicular bulgeIncrease uterine tone, presence of vesicular bulge

External PalpationExternal Palpation

External abdominal palpation as used in External abdominal palpation as used in small animals is not possible in large small animals is not possible in large animals.animals.

You place both fists against the lower flank You place both fists against the lower flank area on the mare and rapidly press area on the mare and rapidly press inward; this displaces the pregnant uterus inward; this displaces the pregnant uterus (if present) and rebounds back into the (if present) and rebounds back into the original position by “bumping” against your original position by “bumping” against your fists. This method lacks accuracy and is fists. This method lacks accuracy and is not typically done.not typically done.

Abdominal RadiographsAbdominal Radiographs

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

““Wee-Foal-Checker”Wee-Foal-Checker”Urine pregnancy test for maresUrine pregnancy test for mares

Laboratory TestsLaboratory Tests

Used when rectal exams are inconclusive or Used when rectal exams are inconclusive or impossible to perform.impossible to perform.

Can be difficult to interpret and have limited Can be difficult to interpret and have limited usefulness. You usually can only perform usefulness. You usually can only perform these during the later stages of pregnancy.these during the later stages of pregnancy.

Progesterone assay- (16-24d) nonspecific, Progesterone assay- (16-24d) nonspecific, high values may mean functional CLhigh values may mean functional CL

Estrogen- (60-100d) higher then during Estrogen- (60-100d) higher then during estrusestrus

Natural Breeding vs. Artificial Natural Breeding vs. Artificial InseminationInsemination

More efficient use of More efficient use of semensemen

Reduce transmission Reduce transmission of diseases from of diseases from stallion to marestallion to mare

Reduce risk of Reduce risk of breeding injuries in breeding injuries in maremare

Success of AI Success of AI requires greater requires greater knowledge and skillknowledge and skill

Increased costIncreased cost Greater risk of human Greater risk of human

injury during injury during collectionscollections

ADVANTAGES: DISADVANTAGES:

Embryo Transfer, Why?Embryo Transfer, Why?

Foals from older, Foals from older, injured, or sub fertile injured, or sub fertile maresmares

Access to wider gene Access to wider gene poolpool

Increase production Increase production and profit on and profit on genetically superior genetically superior maremare

Get embryo from Get embryo from mares who foal late in mares who foal late in seasonseason

Foals from 2 year old Foals from 2 year old maresmares

Foals form mares in Foals form mares in competitioncompetition

Embryo Transfer, why not?Embryo Transfer, why not?

ExpensiveExpensive Need trained Need trained

personellpersonell Embryo recovery can Embryo recovery can

be lowbe low Lack of commercially Lack of commercially

available embryoavailable embryo

Lack of interest by Lack of interest by many registriesmany registries

Many breed Many breed organization do not organization do not accept accept

Harder to Harder to superovulatesuperovulate

Embryo TransferEmbryo Transfer Synchronization of Synchronization of

donor and recipient donor and recipient maremare

Embryo flushingEmbryo flushing Embryo transfer Embryo transfer

procedureprocedure

PGFPGF22

Lutalayse or EstrumateLutalayse or Estrumate

Shorten the interval Shorten the interval between estrous periodsbetween estrous periods

Treatment of a maintained Treatment of a maintained corpus luteumcorpus luteum

After foal heatAfter foal heat Estrous synchronization Estrous synchronization

with prostaglandinswith prostaglandins

Embryo TransferEmbryo Transfer

Ultrasound or palpation for follicular Ultrasound or palpation for follicular development development

Prepare donor mare Prepare donor mare Induce ovulation Induce ovulation Flush 7 to 9 days after ovulationFlush 7 to 9 days after ovulationEmbryos collected in filter cup Embryos collected in filter cup ViewedViewedTransferred within 12 to 24 hoursTransferred within 12 to 24 hours

Recipient MareRecipient Mare

Good health and BCSGood health and BCS Easy to handleEasy to handle Similar in body size to Similar in body size to

donordonor 4-10 years old4-10 years old Sound breeding Sound breeding

conditioncondition Responsive to teaserResponsive to teaser Regular cyclingRegular cycling cheapcheap