1. EQUINE REPRODUCTION

2. TERMINOLOGY BOOK BOOKING FEES STUD FEE FOAL GUARANTEE Live Foal Return
Color
WET/DRY CARE
BREEDER
Thoroughbred
Other breeds
DEATH & SALES CLAUSE
CHUTE FEE

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

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

5. 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

6. 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

7. MARES TERMS Anestrus Pregnant Diestrus Open Estrous Barren Estrus
MARE CLASSIFICATION
Pregnant
Open
Barren
Maiden
Wet
Dry
TERMS
Anestrus
Diestrus
Estrous
Estrus
Anestrus – The period when most mares show no signs of reproductive activity at all.
Diestrus – The period when the mare is not receptive to the stallion (usually lasts days)
Estrous – Entire reproductive cycle. The average length of the estrous cycle is days (from one ovulation to the next).
Estrus – Refers to “heat”, the period when the mare is receptive to the stallion (usually lasts 5-6 days).

8. The Open Mare Evaluate reproductive history
Establish the time of year to breed
Mare Plan:
Diagnose possible problems
Implement problem management
Establish estrus calendar

9. Mares Cycle
Percent

10. Photoperiod Effect
Reproductive activity in spring is stimulated by an increasing photoperiod
Mechanism
Alteration of hormone secretion by the pineal gland and hypothalamus

11. J F M A M J J A S O N D Increasing day length Decreasing day length
Receptors in eye
Neuropathway
Neuropathway
Pineal gland
Decreasing melatonin
Increasing melatonin
Hypothalamus
Increasing GnRH
Decreasing GnRH
Photoperiod Effect
Reproductive activity in spring is stimulated by an increasing photoperiod
Mechanism
Alteration of hormone secretion by the pineal gland and hypothalamus
Anterior pituitary
Decreasing
gonadotropins
Increasing
gonadotropins
Ovaries

12. Transition Period
Increased photoperiod stimulates the hypothalamus and pituitary
Pituitary hormones (especially FSH) induce follicular development

13. 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.

14. 21-day estrous cycle
Estrus 5-7 d
Diestrus d

15. Estrous Cycle Sun Mon Tue Wed Thu Fri Sat 1 2 3 4 5 6 7 8 9 10 11 1213 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
Note:
5 days estrus. To estimate the next cycle, count 21 days from the 1st day of estrus or 15 days from the last day of estrus.

16. Estrus Follicular Development & Ovulation
Anterior Pituitary – FSH - follicular growth
Pituitary – LH – maturation of follicle & ovulation
Follicles reach mm in diameter, secrete estrogen.

17. 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

18. Diestrus Corpus Luteum Formation
Corpus luteum - secretion of progesterone.
Progesterone - responsible for keeping the mare out of heat and for maintaining pregnancy.
Prostaglandin Release
Prostaglandin (PGF) - released from the uterus of a non-pregnant mare days after ovulation

19. Postpartum Estrus Foal Heat Fertile as compared to other species.
Breeding may be necessary to maintain the 12 mo. Foaling interval.
May be necessary to back up foaling.

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

21. Manipulation Methods Artificial lighting Shortening Late Transition
Inducing Ovulation
Estrus synchronization
Estrus Synchronization & Ovulation Induction

22. Light Stimulus
16 hrs daylight per day
30-60 days

23. Progesterone or related compounds
Regumate – most common
Normalization of estrus
Regulation of estrus
Estrus synchronization
Long-term suppression of estrus
Delay foal heat
Pregnancy maintenance
Normalization of estrus in the early breeding season.
Control of estrus in mares exposed to artificial light.
Regulation of estrus in cycling mares.
Appointment breeding.
Estrus suppression in performance mares.
Delaying foal heat.
Pregnancy maintenance.

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

25. Breeding Methods Pasture Breeding Hand Breeding
Artificial Insemination
Fresh semen
Cooled, shipped semen
Frozen semen

26. Cooled Shipped Semen ADVANTAGES Cost Genetics Disease DISADVANTAGES
Technology/management
Stallion variability
Common Problems
Inability to obtain semen
Poor quality semen
Reordering semen
Failure to predict ovulation
ADVANTAGES
Cost
No mare care or shipping expenses
Genetics
Potential access to higher quality
Disease
Decreased transmission of std’s
DISADVANTAGES
Cost & shipment
Veterinary/technician expenses
Technology/management
Competent individuals
Stallion variability DISADVANTAGES
Stallion variability

27. Frozen Semen Success of Frozen Semen Maximum Success
Fertility of stallion’s semen
Fertility of the mare
Skill of the veterinarian/technician
Maximum Success
Client communication
Choose ideal candidate
History of stallion

28. Embryo Transfer Synchronization of donor and recipient mare
Embryo flushing
Embryo transfer procedure

30. TEN FACTORS INFLUENCING PREGNANCY & PREGNANCY LOSS PER CYCLE
MARE AGE
BARREN REPRODUCTIVE STATUS
EARLY BREEDING DATE
LATE BREEDING DATE
BREEDING FREQUENCY
PROSTAGLANDIN FACTOR
UTERINE CULTURE & CYTOLOGY
EFFECT OF SEMEN EXTENDER
POST-BREEDING ANTIBIOTIC INFUSIONS
TWINS

31. Pregnancy Evaluation Ultrasound, 14-18 days ID twins
ID placental development
Re-evaluate, 40 days
Monitor Placental function & fetal growth

32. Gestation Length Normal: 335-342 days Summer 7-10 days shorter
Winter - longer

33. GROWTH CURVE
CR in cm
Gestation age in days

34. Late Pregnancy Abdomen greatly enlarged Ventral edema
Mammary gland enlargement – 2-4 wk
Gluteal muscles relax – 7-10 d
Teats fill with milk – 4-7 d
Waxing of teat ends – 1-4 d
Vulva soft & relaxed – 1-2 d

35. Stages of Parturition Stage 1 Stage 2
Onset: initial uterine contractions
End: rupture of chorioallantois (water bag)
Stage 2
Onset: rupture of chorioallantois
End: delivery of fetus

36. Stages of Parturition Stage 3 (< 3 hrs) Onset: delivery of fetus
End: passage of the fetal membranes

37. Foals and Immunity Colostrum (first milk) - antibodies
1-2 pts of high quality colostrum
If adequate passive transfer occurs there will be over mg/dl IgG in foal’s blood
Takes ~ 12 hours for all antibodies ingested in colostrum to show up in the blood

38. Key points
First two weeks- lay the groundwork by ensuring adequate colostrum
Preventative health program in place
Appropriate nutrition
Problems must be addressed rapidly when they arise. No time for a “wait and see” attitude