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  1. Reproductive Structures and Cycles in Livestock
  2. Terminology • Reproductive cyclicity – Provides females with repeated opportunities to become pregnant • Estrous Cycle – Physiologic events that occur between periods of sexual receptivity and/or ovulations • Estrus – Period of female sexual receptivity
  3. Terminology • Castration – Removing the testicles of the male to prevent breeding • Anestrus – Condition when females do not exhibit regular estrous cycles • Gestation – Time an animal is pregnant
  4. Terminology • Parturition – The act of giving birth • Lactation – Period of time that milk is secreted by the mammary glands • Colustrum – First milk containing a high content of antibodies providing temporary immunity to the offspring
  5. The Female Reproductive System Objective: Identify the parts of the female reproductive system of livestock
  6. Female Tract
  7. Suspensory Ligaments • Broad Ligament – Supports and suspends tract – Provides vascular supply – Lymphatic drainage – Nerves • Composed of: – Mesometrium (Body) – Mesosalpinx (oviduct) – Mesovarium (ovary)
  8. Suspensory Ligaments
  9. Ovary • Female gonad comparable to the male testicle – Site of gamete production – Bovine have 20,000 potential eggs (ova) per ovary, humans have 400,000 potential eggs per ovary – Ova are fully developed at puberty and are not continuously produced as in the male – The hen has only a left functioning ovary
  10. Ovaries Continued • Suspended by mesovarium • Shape varies by species – Cattle-almond shaped – Horses- bean shaped – Sheep- round – Swine- lobular
  11. Ovaries of various species Sow ovary Ewe ovary Cow ovary Mare
  12. Functions of the Ovaries • Gamete production • Secrete estrogen (hormone) • absence of muscle development • development of mammary glands • development of reproductive systems and external genitalia • fat deposition on hips and stomach (source of energy) • triggering of heat • Form the corpus luteum
  13. Oviducts (Fallopian Tubes) • Pair of small tubes leading from the ovaries to the horns of the uterus – Site of fertilization – Supported by mesosalpinx – 3 to 4 days for egg to travel down oviducts • Infundibulum - funnel shaped portion of the fallopian tube that catches the ovulated egg
  14. Oviducts (Fallopian Tubes) • Functions: – Ovum transport – Sperm storage and capacitation – Fertilization (AI) – Early embryo development
  15. Female Reproductive System ovary infundibulum uterus
  16. Uterus • Muscular sac connecting fallopian tubes and cervix • Consists of a body and two horns – Cow, ewe, and mare (bicornuate) – Sow has only horns, no body – Woman has no horns (simplex)
  17. Uterus Functions • Sustains sperm and aids in its transport • Maternal placenta - supports embryo and fetus during gestation • Expels fetus at parturition • Control of cyclicity
  18. Female Reproductive System
  19. Cervix • Area between the uterus and vagina • Normally closed; opens at estrus and parturition • Functions: – Lubrication – Flushing – Barrier to foreign material or bacteria
  20. Cervix – Species Differences • Cow and ewe - annular rings • Sow - corkscrew • Mare - longitudinal folds
  21. Vagina and Vulva • Vagina: connects the cervix to the external genitalia and serves as the female copulatory organ • Vulva: external tissue of the female reproductive tract, receives penis during copulation
  22. Female Reproductive System
  23. Reproductive Tract of Cow
  24. Sow
  25. Reproductive Tract of the Ewe
  26. Reproductive Tract of the Mare
  27. Reproductive Functions (Female) • Steps in the female reproductive process: 1. Ovulation — Produce gamete (ova or ovum) — Release of egg(s) — Infundibulum pushes the ovum into the fallopian tube
  28. Reproductive Functions (Female)
  29. Ovulation Rates by Species Species Ovulation Rate Cow 1 egg/estrus Ewe 1 - 3 eggs/estrus Sow 10 - 20 eggs/estrus Mare 1 egg/estrus Hen ~ 28 eggs/month
  30. Reproductive Functions (Female) 2. Estrus (heat, estrous period) – Period of time when a female will accept a male in copulation – The female must stand (standing heat) to be mounted before the reproductive process can begin – Estrus detection methods: visual inspection, teaser animals, marker aids
  31. Types of Cyclicity • Polyestrus - uniform distribution of estrous cycles occurring regularly throughout the year – Cow, sow • Seasonal Polyestrus - “periods” of estrous cycles occurring only during certain seasons of the year – Sheep, goat, deer, mare • Monoestrus - only one cycle per year, often lasting several days – Dogs, wolves, bear, fox
  32. Timing of Events in the Reproductive Cycle Species Length of Estrous Cycle Duration of Estrus Time of ovulation Ewe 17 days 24-36 hours 24-30 hrs from estrus onset Goat 21 days 32-40 hours 30-36 hrs from estrus onset Sow 21 days 48-72 hours 35-45 hrs from estrus onset Cow 21 days 18-19 hours 10-11 hrs after onset of estrus Mare 21 days 4-8 days 1-2 days before end of estrus
  33. Reproductive Functions (Female) 3. Gestation — Fertilization to parturition — Develop embryo in uterus 4. Parturition — Expel fully developed young at birth 5. Lactation — Milk production
  34. Reproductive Terminology Species Act Offspring Cow calving calf Ewe lambing lamb Sow farrowing piglet Hen hatching chick Mare foaling foal Goat kidding kid
  35. Gestation and Lactation Periods Species Gestation Period (days) Lactation Period (days) Cow 275 - 285 beef 180 - 270 dairy 305 - 365 Ewe 115 - 142 60 - 90 - 120 Sow 112 - 115 21 - 42 Mare 330 - 345 90 - 150 Woman 270 ? (years)
  36. Reproductive Functions (Female)
  37. The Male Reproductive Tract Objective: Identify the parts of the male reproductive system of livestock and poultry
  38. Male Reproductive Tract
  39. Male Reproductive Tract • Scrotum - external sac that holds testicles outside of the body – Maintains sperm 4-5oF cooler than the body temperature • Testicles - primary male organs of reproduction – Produce sperm – Secrete testosterone
  40. Cryptorchidism • Failure of one or both testes to descend into the scrotum – Unilateral: one testis does not descend •testis that descends is fertile; reduced sperm concentrations – Bilateral- neither testes descend into scrotum •Results in sterility due to elevated temperature of both testes
  41. Male Reproductive Tract • Epididymis: long coiled tube that is a path for sperm – Provide passageway for sperm out of the seminiferous tubules – Storage for sperm – Fluid secretion to nourish sperm – Place for sperm maturation
  42. Male Reproductive Tract • Vas Deferens - slender tube from epididymis to urethra – Moves sperm to the urethra at ejaculation • Urethra - long tube from bladder to penis – Passageway for urine and sperm out of the body
  43. Male Reproductive Tract • Penis - male organ of copulation which conveys semen and urine out of the body • Penis retractor muscle - allows extension and retraction of the penis; sigmoid flexure extends in copulation
  44. Fibroelastic vs. Vascular Penis • Fibroelastic: erection extends the length of penis rather than diameter – Bull, Ram, Boar • Vascular: composed of specialized tissues that fill with blood causing the penis to become turgid during erection – Stallion
  45. Male Reproductive Tract Accessory Glands: • Seminal vesicles- add fructose and citric acid to nourish the sperm • Prostate Gland - located at the neck of the bladder – Cleans the urethra prior to and during ejaculation – Provides minerals for sperm – Provides the medium for sperm transport – Gives semen it’s characteristic odor
  46. Male Reproductive Tract • Cowper’s gland •Also called the Bulbourethral gland •Paired organs •cleans the urethra prior to semen passage
  47. Male Reproductive Tract
  48. Differences in Tracts • Bulls- Pendulous, perpendicular testes • Ram- Pendulous, perpendicular testes; Filiform appendage • Boar- Inverted testes; No ampulla; corkscrew penis; much larger bulbourethral gland • Stallion-Horizontal testis; loosely attached tail of epididymis; Smooth seminal vesicles; no sigmoid flexure
  49. Bull Reproductive Tract
  50. Ram Reproductive Tract
  51. Boar Reproductive Tract
  52. Stallion Reproductive Tract
  53. Reproduction in Poultry Objective: Specify how the reproductive system for poultry functions
  54. Reproduction in Poultry The poultry oviduct has five parts: 1) Vagina – Holds the egg until laid 2) Uterus – Secretes the shell 3) Isthmus – Adds the two shell membranes 4) Magnum – Secretes the albumen 5) Infundibulum – Where fertilization takes place
  55. Reproduction in Poultry • Major difference: – Embryo of livestock develop inside the female’s body while the embryo of poultry develops inside the egg. • Poultry only have the left ovary and oviduct when mature • The yoke is the ovum • Chicken Incubation – 21 days

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