Equine Reproduction LACP Chapter 6 pages 157 165

Equine Reproduction LACP Chapter 6, pages 157 -165

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

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

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

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

Male Evaluation l l l l Penis Prepuce/sheath Scrotum Testicles Semen analysis Venereal disease Physical exam Female Evaluation l l l Rectal palpation Ultrasound exam of the ovaries, uterus, and cervix Visual exam of the vagina and cervix Uterine culture Possibly a endometrial biopsy

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

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

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!

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

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

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

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

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

Number of Sperm Depends On: l Seasonal Influences (Photoperiod) l Effected Areas Ejaculate volume l Sperm numbers l Total sperm/ejaculate l Sperm motility l Willingness to breed l Mounts before breeding l Scrotal size l Testosterone production l

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

Semen Collection and Storage Artificial vagina collection most common l Avoid contact with air, sunlight, and extreme heat and cold l Fresh l l Use l within 24 hours Frozen l 0. 5 -ml straws l 500 million progressively motile sperm per insemination

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.

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? docid=2 375536614971713657&ei=nt. ISrar. Dpj 0 q. APFv. P 2 WCg&q=stallion+semen +collection&hl=en l http: //www. youtube. com/watch? v=y. SUq 0 x HIBig l

General Semen Analysis Appearance l Volume l Concentration of sperm l Number of sperm l Sperm morphology l Live sperm % l Sperm motility l p. H (7. 2 -7. 5) l

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

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

Female Reproductive System l l l 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 1 st 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 l Vagina l Cervix l Uterus l Oviducts l Ovaries l Left Ovary Oviduct Cervix Left Uterine Horn Uterine Body Vagina

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. l This can be done either indoor or outdoor. This should be done in the evening and not the morning. l CTVT pg. 381

Reproductive Physiology of the Mare Estrus Cycle: 15 -26 days (21) l Estrus: 4 -7 days l Ovulation: last 48 hrs. of estrus l Gestation: 11 months (330 -345 days) light breeds (305 -365 days) l LACP pg. 157

Percent Mares Cycle

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

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 l PGF 2α – shortens CL life span l

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

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

Transition l l l 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

Prediction of Ovulation Number of days in heat l Growth rate of largest follicle l l Average 3 -5 mm/day Size of largest follicle l 35 millimeters l Softness of preovulatory follicle l Ultrasound image l

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

Equine Breeding l l l 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 l Diagnostic Ultrasound, per rectum l Diagnostic Ultrasound, Transabdominal l External Palpation l Abdominal Radiographs l Laboratory Tests l

Preparation of the Perineum/vulva l Both areas should be cleansed so that you do not contaminate the vagina, cervix and uterus with fecal material and other debris. l Tail should be wrapped or bandaged. LACP pg. 282

Cleaning l l 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. 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. l 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. l

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. l 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. l

Abdominal Radiographs l 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. l Can be difficult to interpret and have limited usefulness. You usually can only perform these during the later stages of pregnancy. l Progesterone assay- (16 -24 d) nonspecific, high values may mean functional CL l Estrogen- (60 -100 d) higher then during estrus l

Natural Breeding vs. Artificial Insemination ADVANTAGES: l l l More efficient use of semen Reduce transmission of diseases from stallion to mare Reduce risk of breeding injuries in mare DISADVANTAGES: l l l Success of AI requires greater knowledge and skill Increased cost Greater risk of human injury during collections

Embryo Transfer, Why? l l l Foals from older, injured, or sub fertile mares Access to wider gene pool Increase production and profit on genetically superior mare l l l Get embryo from mares who foal late in season Foals from 2 year old mares Foals from mares in competition

Embryo Transfer, why not? l l Expensive Need trained personell Embryo recovery can be low Lack of commercially available embryo l l l Lack of interest by many registries Many breed organization do not accept Harder to superovulate

Embryo Transfer l l l Synchronization of donor and recipient mare Embryo flushing Embryo transfer procedure

PGF 2 Lutalayse or Estrumate u u 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 l Prepare donor mare l Induce ovulation l Flush 7 to 9 days after ovulation l Embryos collected in filter cup l Viewed l Transferred within 12 to 24 hours l

Recipient Mare l l l l 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