Reproduction

1. Reproduction

2. Efficiency of reproduction is the single most important trait to consider in the production of meat and fiber. More money is made and lost due to either the ability to or failure to reproduce. It includes an understanding of hormones, anatomy and physiology and management. Introduction

3. Puberty- sexual maturity Ovulation- release of ovum (egg) from ovary Copulation- the act of mating Fertilization- union of male and female sex cells Conception- becoming pregnant Reproduction Terms

4. Estrous Cycle- the interval between two estrus periods Estrus- the time of receptivity to mating during the estrous cycle; also termed as “heat” Gestation- pregnancy Parturition- the act of giving birth Reproduction Terms

5. The ovaries-2 in number-produce ova and hormones. • Infundibulum-captures the ova after ovulation • Oviducts or fallopian tubes-site of fertilization • Uterine horns-leads from oviduct to body of uterus, site of implantation in many-litter species • Uterine body-site of implantation in non-litter species • Cervix-guards the uterus • Vagina-copulation, parturition • Vulva-external genetalia Female anatomy

6. Female anatomy

7. Female Tract

8. Scrotum- container for the testes, functions in temperature regulation • Testes(2)-produce sperm and hormones • Epididymus-store, transport, mature, conc. • Vas deferens-ejaculation • Ampulla-widening of tract • Seminal vesicles-50% of bulk of semen • Prostate-nutrition • Cowpers-flushes tract • Penis- copulatory organ Male reproductive tract

9. Male anatomy

10. Testes

11. Boar tract

12. Produced in: Hypothalamus-Releasing hormones Anterior Pituitary-Tropic hormones Gonads-Gonadal hormones Uterus-Prostaglandin F2 alpha Placenta-Steroids & gonadotropins Stored in Posterior Pituitary-oxytocin Hormones

13. Anterior pit and hypothal.

14. Gland location

15. Part of lower brain that regulates many functions of the body including thirst, hunger, reproduction etc. Produces releasing hormones for the release of tropic hormones from the anterior pituitary Anterior pituitary-Small gland in skull that produces 7 tropic hormones. Hypothalamus

16. Gonads-testes and ovaries produce reproductive hormones involved in estrus, ovulation, pregnancy and parturition. Uterus-produces prostaglandin F2 alpha which is lutylase. Placenta-produces progesterone, estrogen and species specific gonadotropins (PMSG & HCG). Endocrine glands

17. Beginning with puberty (age at first estrus or ejaculation) Gonadotropin Releasing Hormone (GnRH) from the hypothalamus is secreted from the hypothalamus through a closed blood supply directly into the anterior pituitary where it stimulates the release of Follicle Stimulating Hormone (FSH). The hormone cycle

18. FSH stimulates the follicle to begin the formation of the phases of follicular development. The interior lining of the follicle produces estrogens under FSH influence. As estrogens rise in the blood stream, the reproductive tract is prepared for pregnancy and the female’s behavior changes (estrus). Cycle 2

19. Follicular development

20. Estrous cycle

21. When the follicle matures, estrogen is at its peak of secretion which acts on the anterior pituitary to inhibit FSH release and allows GnRH to cause the release of a surge of luteinizing hormone (LH). This surge of LH causes a softening of the follicle which leads to ovulation. Cycle 3

22. Hormone cycle

23. LH continues to act on the ovulation site (corpus hemorrhagicum) to change it into a corpus luteum which produces a steroid hormone progesterone. Progesterone has the opposite effects of estrogens in that estrus is suppressed and the uterus is maintained in a pregnant state. Cycle 4

24. If fertilization occurs, LH maintains the corpus luteum and progesterone is secreted, maintaining pregnancy for the allotted times. Pregnancy lengths: cattle-283 days, sheep and goats 150 days, swine-114 days and horses-330 days. Cycle 5

25. If fertilization fails, the uterus senses the absence of an embryo and releases a pseudohormone, prostaglandin F2 alpha on day 14 of the cycle. • PGF2 alpha acts on the CL to destroy it thus dropping progesterone in the blood which releases the inhibition of GnRH and the cycle begins again on day 18 with estrus occurring on day 21. Cycle 6

26. Fertilization occurs in the oviduct and the fertilized egg reaches the uterine horn in 4 days. • Over the next 45 days, the embryo develops an attachment to the wall of the uterus by implanting its placenta which serves the fetus by transferring oxygen/CO2, nutrients and waste products from the maternal blood to the fetal blood streams. Pregnancy

27. Embryonic development

28. When the fetus is fully developed its adrenal gland secretes adrenal corticosteroids which stimulates PGF2 alpha to be released by the uterus. • This destroys the CL and allows estrogens from the placenta to begin mild contractions. These contractions cause a reflex release of oxytocin from the posterior pituitary which stimulates increasingly stronger contractions. Parturition

29. As the fetus is delivered, (front legs first with head resting on hooves), contractions continue until the placenta is loosened from its attachment to the uterine wall. Once the placenta is delivered, parturition is complete. Parturition 2

30. The mammary gland has developed over the last 1/3 of gestation under the influence of progesterone, estrogen and luteotropic hormone (LTH) from the anterior pituitary. Oxytocin then causes muscle contractions in the udder to cause milk letdown and lactation. Lactation

31. Female born twin to a male Female generally has incomplete reproductive tract; over 90% are infertile Fetal membranes anatomose (connect); compounds from the male fetus inhibit normal development of female Freemartins

32. Rectrovaginal technique

33. Artificial Vagina