Equine Reproduction LACP Chapter 6, pages 157-165

Equine Breeding Data Type of estrous cycle Age of female at puberty Seasonally polyestrous (long day breeder) Age of female at puberty 10 to 24 months Age of male at puberty 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)

Equine Breeding Data (cont’d) 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

Selecting a Mare and Stallion Physical characteristics Temperament Athletic potential Evaluate previous foals, reproductive ability The four “P’s” Phenotype Performance Pedigree- proves parentage not quality Progeny

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

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

Puberty of the Male This is the age when a male can impregnate a female. 10 – 24 months of ages Castration or Gelding …

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

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 hot-hot-hot!

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

Beans are bad! The beans can compress the tip of the urethra and make urination difficult and very painful.

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.

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

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

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

Semen Collection Quality and quantity of sperm Evaluate diseases of the male reproductive tract AI=artificial insemination

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

Breeding phantom (Phantom) for semen collection. Can be adjusted Good footing, correct height, can use with a teaser mare, can use AV inside dummy. Collect every other day allows maximum harvest with minimal labor/risk of injury Breeding phantom (Phantom) for semen collection. Can be adjusted to a comfortable height for the stallion

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

Optimal temperature inside the AV is AV=Artificial vagina Optimal temperature inside the AV is approximately 113°F (48°C)

Colorado Style Missouri

French INRA model Roanoke model

http://video. google. com/videoplay 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 Analysis Appearance Volume Concentration of sperm Number of sperm Sperm morphology Live sperm % Sperm motility pH (7.2-7.5) Volume- 50-75mL Motility-(use warm slide) normal 75-80%, Concentration- 200-500 x10^6 per dose, concentration X volume= total # of sperm, morphaology- 90% or better,

Artificial Insemination Inseminate pipette into the uterus Multiple inseminations 24 to 48 hours apart Common to use ultrasound to monitor follicular growth Extenders- protection, increased insemination volume, prolonged sperm survivial, enhanced fertility, optimal pH and osmotic pressure, protection against cold shock

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

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

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

Mare Anatomy Vulva Vagina Cervix Uterus Oviducts Ovaries Left Ovary Ovary – 2X1.5” in diameter. Located on pinched in face of ovary is ovulation fossa – unique anatomical feature of equine ovary. Oviducts = ~8-12”long. Uterus – Body & 2 horns. 8” wide X 3” wide Cervix – 2-3”. Longitudinal folds Vagina – 7-9” long & 4-5” diameter Left Uterine Horn Uterine Body

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. Also hormone use to induce ovulation, CTVT pg. 381

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

Mares Cycle Percent

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

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 PGF2α – shortens CL life span

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

Hormonal Manipulation Administer PGF2α 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)

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 Increased photoperiod stimulates the hypothalamus and pituitary Pituitary hormones (especially FSH) induce follicular development Note – Multiple follicles on ovary.

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 Ovulation normally occurs when follicle reaches 4-5 cm

Signs of Estrus Most consistent Other supporting signs Elevated tail raise Winking Other supporting signs Leaning Squatting Standing still Urinating

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

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

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

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.

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

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

Diagnostic Ultrasound 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 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 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.

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.

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

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.

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

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

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

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

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

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

Embryo Transfer Synchronization of donor and recipient mare Embryo flushing Embryo transfer procedure First performed in 1972

PGF2 Lutalayse or Estrumate Shorten the interval between estrous periods Treatment of a maintained corpus luteum After foal heat Estrous synchronization with prostaglandins

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

Insert catheter with cuff, inflate cuff anddraw back for tight seal, gravity flow with flushing media infused and immediately drained into receptal with filter, usually done at least twice, recovered fluid searched for embryo, embryo measure and given quality score, usually transferred with 1 hr or frozen

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