The Reproductive System of a Mare Livestock Production, Equine Science, Advanced Animal Science Have students fill in their diagram to the best of their ability.

Introduction to the Estrous Cycle The recurring reproductive cycle in many female mammals, including estrus, ovulation, and changes in the uterine lining. Differs from the menstrual cycle in that the endometrium is not shed Generally, species with estrous cycles are not sexually active when they are not in the estrus phase of their cycle

The Estrous Cycle Estrus (Follicular) – period when mare is sexually receptive to stallion, the “heat” stage Diestrus (Luteal) – period when mare is not sexually receptive

The Estrous Cycle (cont.) Helps the mare physically prepare for conception Generally, the cycles occur between spring and fall (when the days are longer) 18 - 21 days long

Terminology Anestrus – complete absence of estrus, prevents mares from conceiving during the winter months Seasonally polyestrus – mares go through regular estrus cycles during part of the year

The Parts Vulva – the external opening of the reproductive canal Vagina – 6-8 inch long muscular membrane connecting the vulva to cervix; tissues are elastic to accommodate penis during breeding and foal during birth Cervix – about 4 inches, elastic muscle, located behind vagina See if Slides 6 and 7 help the students label the parts of the reproductive system

Uterus – contains 2 branches that are referred to as “horns”; protects and nourishes the embryo/fetus Oviducts –attached to each uterine horn; transports the discharged egg from the ovaries; the mare’s Fallopian tubes Ovaries – 2-3 inch bean- shaped organs; contains follicles that hold the mare’s egg cells

Reproductive Anatomy Pause on this slide to give students time to complete their diagrams correctly.

During estrus……. Vagina becomes relaxed and secretions increase Vulva relaxes Cervix increases secretions, opens, and relaxes Uterus becomes heavier, losing its tone, due to increased levels of estrogen Use the diagram to point out each organ as you are discussing its function.

Signs of Estrus Frequent urination “Squatting” posture Winking of labia Raising of tail Receptive toward stallion Discharge from vagina

Breeding Tips Have a vet examine the mare and stallion for diseases and evaluate the chances of conceiving Wash the mare’s (and stallion’s) genitals with warm non-soapy water to minimize the chances of dirt and bacteria entering during the mating process Wrap the upper 1/3 of mare’s tail with a clean wrap so that there is a smaller chance of it getting in the way SOAP is never used because it can kill sperm cells. This drastically decreases the chances of pregnancy.

Breeding Methods Live Cover – methods in which mare and stallion are physically brought together to breed Hand Mating – most widely used; people handle both mare and stallion Corral Mating – mare and stallion are turned into a paddock where they mate naturally Pasture Mating – stallion is turned out with a group of mares for the entire breeding season Video of horses mating: http://www.youtube.com/watch?v=VRQtHv_M7wk

Alternative Breeding Methods Artificial Insemination (AI) – mare is inseminated by a veterinarian Embryo Transfer – removing the embryo from a mare and transferring it to a surrogate mare The AI procedure: http://www.smartlilplayer.com/html/ai.html

Artificial Insemination (AI) Pros Cons Semen sample from stallion can be used for more than one mare Frozen semen can be stored for long periods of time, making international breeding possible Chances of contamination in the mare is reduced Smaller chance of injury to both the stallion and mare Humans handle every step of this process, so there is a higher chance of human error Various competition organizations, such as The Jockey Club, does not allow competing horses to be bred through AI

Important Hormones Estrogen – Progesterone – Secreted by follicles Hormone that causes the pituitary gland to secrete more LH Makes mare more receptive toward stallion Prepares mare for conception physically Peaks 1-2 days before ovulation Progesterone – Prevents conception and decreases the receptiveness of the mare to the stallion Causes cervix to close At its lowest level during the estrus phase Suppresses hormonal activity to maintain pregnancy (if mare is pregnant) If mare is not pregnant, the estrous cycle will continue

More Hormones Luteinizing hormone (LH) – Secreted by the pituitary Assists the maturation of the follicle Follicle stimulating hormone (FSH) – Secreted by pituitary, transported through bloodstream to ovaries Stimulates the production of follicles For more information on hormones: http://www.equine-reproduction.com/articles/estrous.htm