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Unformatted text preview: Ansci 206 - Equine Reproduction Puberty Filly 12-15 months Colt 12-15 months Seasonality of the Mare Seasonally polyestrous Fertile period of estrous cycles from early spring to early fall ANESTRUS (without estrus, not fertile) during the winter months Important in the wild foals born in spring/summer Most mares are transitional (irregular cycles) during very early spring after winter anestrus and during fall before winter anestrus. Estrous Cycle of the Mare (cont.) 21 days total average duration 5-7 days estrus (heat) fertile period, receptive to stallion 14-16 days diestrus (not fertile, reject stallion) Estrus (Heat) Detection Teasing presenting stallion to mare In estrus: tail raising, urination (frequent small amounts), move towards stallion, clitoral winking Not in estrus: kicking, squealing, ears pinned, tail clamped, move away from stallion Ovulation release of mature ovum (egg) from follicle on mare's ovary Occurs 24-48 hours before the end of estrus Time of breeding should be close to ovulation. About 12 hours before is optimal, but may get conception as late as 12 hours after ovulation Mare's follicle is usually at least 35 50 mm in diameter at ovulation How to determine ovulation? Teasing Rectal Palpation Ultrasound How often to breed? After the follicle is about 35 mm in diameter, breed every other day until ovulation is detected Breeding Methods Natural Cover May work well for breeding small number of mares May be more dangerous for the stallion greater chance of injury May improve conception rate Artificial Insemination Stallion is collected with artificial vagina (AV) and mare is inseminated with pipette Can maximize the production of a genetically superior stallion, but may overproduce certain bloodlines, possibly restrict available genetics Semen Quality Evaluation Stallion's semen should be checked for: Motility Concentration Total number Morphology Gestation in the mare With good management, should get 80%+ conception rate and 70%+ live foal rate. National average live foal rate only ~ 50% Total time of pregnancy the period from conception to the birth of the foal about 340 days average Colts may be carried 3-4 days longer than fillies Late gestation changes in the mare Filling of the udder 3-6 weeks prior Waxing of teats 2-3 days prior, sometimes only hours Relaxation of ligaments around tail head few days prior Relaxation/elongation of vulva few days prior Parturition (Foaling) 3 Stages: Stage 1 Preparation Lasts 1-4 hours (highly variable) Stage 2 Active Labor Usually only 15-60 minutes Stage 3 Placental Passage Up to 3 hours or more after 6 hours, retained placenta call the vet! Late Stage 1 Stage 2 Stage 2 Stage 2 Stage 2 Stage 2 Stage 3 Stage 3 End of Stage 3 Full passage of Placenta Mare Reproductive Tract Ovary Uterus Cervix Vagina Mesometrium (Broad Ligament) Bladder Vulva Clitoris Uterus Uterine Horn Utero-Tubal Junction Ovary Large Graafian Follicle Oviduct Infundibulum Endometrium Ovulation Fossa Uterine Body Cervix Os Cervix & Fornix Vagina Ovary Cervix Uterine Body Cervical Os Fornix Vagina Vagina Stallion Reproductive Tract Glans Penis Vas Deferens External Cremaster Muscle Epididymis Testis Stallion - Testis Caput Epididymis External Cremaster Muscle Testis Corpus Epididymis Vas Deferens Cauda Epididymis Ampulla Accessory Glands Ampulla Cowpers (bulbourethral) Bladder Prostate Seminal Vesicle Stallion - Glans Penis Glans Penis Urethral Process ...
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- Spring '08