Reproduction06

EQUINE REPRODUCTION: 

EQUINE REPRODUCTION

TERMINOLOGY: 

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

Stallion Physiology: 

Stallion Physiology

Sperm Production: 

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

Number of Sperm Depends On:: 

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

Mare Anatomy: 

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

MARES: 

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

The Open Mare: 

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

Slide9: 

Mares Cycle Percent

Photoperiod Effect: 

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

Slide11: 

Receptors in eye Pineal gland Hypothalamus Anterior pituitary Ovaries Increasing day length Decreasing day length Neuropathway Neuropathway Decreasing melatonin Increasing melatonin Increasing GnRH Decreasing GnRH Increasing gonadotropins Decreasing gonadotropins J F M A M J J A S O N D

Transition Period: 

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

Transition: 

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

Slide14: 

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

Estrous Cycle: 

Estrous Cycle

Estrus: 

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: 

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: 

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 14-16 days after ovulation

Postpartum Estrus: 

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: 

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

Manipulation Methods: 

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

Light Stimulus: 

Light Stimulus 16 hrs daylight per day 30-60 days

Progesterone or related compounds: 

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

PGF2 Lutalayse or Estrumate: 

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

Breeding Methods: 

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

Cooled Shipped Semen: 

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

Frozen Semen: 

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: 

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

TEN FACTORS INFLUENCING PREGNANCY & PREGNANCY LOSS PER CYCLE: 

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

Pregnancy Evaluation: 

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

Gestation Length: 

Gestation Length Normal: 335-342 days

GROWTH CURVE: 

GROWTH CURVE Gestation age in days CR in cm

Late Pregnancy: 

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: 

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: 

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

Foals and Immunity: 

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 IgG in foal’s blood Takes ~ 12 hours for all antibodies ingested in colostrum to show up in the blood

Key points: 

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