EQUINE REPRODUCTION TERMINOLOGY s s BOOKING FEES STUD

EQUINE REPRODUCTION

TERMINOLOGY s s BOOKING FEES STUD FEE FOAL GUARANTEE s Live Foal s Color s s WET/DRY CARE BREEDER s Thoroughbred s Other breeds DEATH CLAUSE CHUTE FEE

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

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

Mare Anatomy • • • Vulva Vagina Cervix Uterus Oviducts Ovaries Left Ovary Oviduct Cervix Vagina Left Uterine Horn Uterine Body

MARES TERMS • Anestrus • Diestrus • Estrous Cycle • Estrus MARE CLASSIFICATION • • • Pregnant Open Barren Wet Dry

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

Mares Cycle

Photoperiod Effect • • Reproductive activity in spring stimulated by an increasing photoperiod Mechanism – Altered hormone secretion by pineal gland – http: //www. vivo. colostate. edu/hbooks/pathphys/end ocrine/otherendo/pineal. h tml

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

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

• 21 -day estrous cycle • Estrus 5 -7 d • Diestrus 14 -16 d

Estrous Cycle Sun Mon Tue Wed Thu Fri Sat 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

• • • Go to CSU site and discuss GONADOTROPINS What does LH and FSH stand for? http: //www. vivo. colostate. edu/ hbooks/pathphys/endocrine/h ypopit/lhfsh. html

Estrus Follicular Development & Ovulation • Anterior Pituitary – FSH - follicular growth • Pituitary – LH – maturation of follicle & ovulation • Follicles reach 20 -25 mm in diameter, secrete estrogen.

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

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 nonpregnant mare 14 -16 days after ovulation

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.

Signs of Estrus • Most consistent – Elevated tail raise – Winking – http: //www. youtube. com/watch? v=Henp 9 Uv 21 Cw • Other signs – Squatting – Urinating whitish – Video of mare interaction http: //www. youtube. com/watch? v=Pu. Gu Z 9 Jy. Ez 4

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

Light Stimulus • • 14. 5 hrs daylight per day (also long days done for hair coat control) 30 -60 days

Progesterone or related compounds l l l Regumate – most common Normalization of estrus Estrus synchronization Long-term suppression of estrus Pregnancy maintenance

Lutalyse or Estrumate u Shorten interval between estrous periods u Break down the CL corpus luteum u Estrous synchronization with prostaglandins http: //www. veterinarypartn er. com/Content. plx? P=A& C=301&A=2720&S=0

Breeding Methods • • • Pasture Breeding Hand Breeding Artificial Insemination – Fresh semen – Cooled, shipped semen – Frozen semen

Cooled Shipped Semen ADVANTAGES • Cost • Genetics • Disease DISADVANTAGES • Cost • Technology/mgmnt • Stallion variability Common Problems • Inability to obtain semen • Poor quality semen • Reordering semen • Failure to predict ovulation

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

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

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

Gestation Length • Normal: 335 -342 days

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

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

Stages of Parturition • Stage 3 (< 3 hrs) – Onset: delivery of fetus – End: passage of the fetal membranes – Foaling video 7 min http: //www. youtube. com/watch? v=3 RS Av_JIQMo

Foals and Immunity • • Colostrum (first milk) antibodies 1 -2 pts of high quality colostrum If adequate passive transfer occurs there will be over 400 -800 mg/dl Ig. G Immunoglobulin antibodies in foal’s blood Takes ~ 12 hours for all antibodies ingested in colostrum to show up in the blood