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Presentation on ESTROUS CYCLE

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ESTROUS CYCLE: Reproductive cycle of female, generally defined as period from one estrus to the next.
Two phases:
Follicular Phase
Luteal phase
TYPES OF ESTROUS CYCLE

Presentation on ESTROUS CYCLE

  1. 1. ESTROUS CYCLEESTROUS CYCLE ByBy Faisal A. AlshamiryFaisal A. Alshamiry Supervision:Supervision: Ayman SwelumAyman Swelum Estrus SynchronizationEstrus Synchronization Estrus SynchronizationEstrus Synchronization Estrus SynchronizationEstrus SynchronizationEstrus SynchronizationEstrus Synchronization
  2. 2. DEFINITIONS: ESTROUS CYCLE: Reproductive cycle of female, generally defined as period from one estrus to the next.  Two phases:  Follicular Phase  Luteal phase
  3. 3. DEFINITIONS :  ESTRUS: Period of sexual receptivity. • Commonly referred to as “Heat”  ANESTRUS: Period when female does not experience cycles • Occurs during pregnancy, etc.
  4. 4. • Cycle is categorized by frequency occurrence throughout the year: – PolyestrusPolyestrus: Uniform distribution of estrous cycles which occur regularly throughout the year • Example: Cattle, Swine, Rodents TYPES OF ESTROUS CYCLE
  5. 5. • Seasonally polyestrus: – Cycles occur only during certain times of the year • Long-day breeders: – Cycle when day length increases Example: Mare • Short-day breeders: – Begin to cycle as day length decreases
  6. 6. • Monoestrus: – One cycle per year • Periods of estrus last for several days – Example: Dogs, Wolves, Foxes, Bears
  7. 7. PHASES OF ESTROUS CYCLEPHASES OF ESTROUS CYCLE • FOLLICULAR PHASE: – Short phase - only 20% of cycle – Period from regression of corpus luteum to ovulation – Preovulatory follicle – Dominant hormone is estradiol
  8. 8. PHASES OF ESTROUS CYCLEPHASES OF ESTROUS CYCLE • LUTEAL PHASE: – Long phase - 80% of cycle – Period from ovulation to corpus luteum regression – Corpora lutea – Dominant hormone is progesterone – Follicle continue to grow and regress during this phase
  9. 9. STAGES OF ESTROUS CYCLESTAGES OF ESTROUS CYCLE • Four stages: – Proestrus – Estrus – Metestrus – Diestrus • Follicular phase = Proestrus + Estrus • Luteal phase = Metestrus + Diestrus
  10. 10. PROESTRUSPROESTRUS • Begins when progesterone declines(luteolysis) and ends at onset of estrus • Lasts 2 to 5 days • Period of major endocrine transition – Progesterone dominance to estrogen dominance – FSH and LH responsible
  11. 11. ProestrusProestrus “Building Up” – Ovarian follicle, with enclosed ovum, increase in size – Estrogens absorbed from the follicles into blood stream stimulate increased vascularity and cell growth of tubular genitalia, in preparation for estrus and pregnancy
  12. 12. EstrusEstrus • Period of sexual receptivity • Large increase in estrogen – stimulates release of LHRHLHRH • FSHFSH decreases due to estrogen and inhibin – During or shortly after estrus, ovulation occurs due to major surge in LHLH – LHLH levels increase due to LHRHLHRH – Estrus stops once ovulation occurs.
  13. 13. MetestrusMetestrus • Corpus Luteum predominant • ↑↑Increase in progesterone, ↆↆ decrease in estrogen • Endometrial lining thickens and uterine muscles show increased development.
  14. 14. DiestrusDiestrus • Relatively short period of time between estrous cycles during the breeding season of polyestrous animals – No reproductive activity
  15. 15. • CL is fully functional* • High levels of progesterone • End with luteolysis • 10 to 14 days (Depending on the species of animal( Prolonged Diestrus *corpora lutea
  16. 16. Summary of Stages • Proestrus= Formation of ovulatory follicle + E2 secretion • Estrus = Sexual recepitivity + peak E2secretion • Metestrus = CL formation + beginning of P4 secretion • Diestrus = Sustained luteal secretion of P4
  17. 17. AnestrusAnestrus • Long period of inactivity between sexual seasons – No regular estrous cycles – Ovaries relatively inactive • No follicles or CL
  18. 18. Average Reproductive CyclesAverage Reproductive Cycles Species Length of Length of Ovulation Length of Estrous Cycle Estrus Pregnancy Cow 21 days 18 hr 11 hr after 282 days polyestrus end estrus Ewe 17 days 29 hr near end 148 days seasonal (fall) estrus Sow 21 days 48-72 hr 35-45 hr 115 days polyestrus after start estrus Mare 21 days 4-8 days 3-6 day of 335 days seasonal (spring) estrus polyestrus (1-2 days before end of estrus) The basic pattern of the estrous cycle is the same in all domestic animals, but some specific differences are found in specific parts of the cycle. Some specifics about relevant farm species are summarized in Table
  19. 19. Characteristics of Estrous CyclesCharacteristics of Estrous CyclesCharacteristics of Estrous CyclesCharacteristics of Estrous Cycles CowCow EweEwe SowSow MareMare Estrous cycle (days)Estrous cycle (days) 2121 1717 2121 2121 Proestrus (days)Proestrus (days) 3-43-4 2-32-3 3-43-4 2-32-3 EstrusEstrus 12-18 hr12-18 hr 24-36 hr24-36 hr 48-72 hr48-72 hr 4-8 days4-8 days Metestrus (days)Metestrus (days) 3-43-4 2-32-3 2-32-3 2-32-3 Diestrus (days)Diestrus (days) 10-1410-14 10-1210-12 11-1311-13 10-1210-12
  20. 20. Variation in Cycle Types Example Type of Follicular Ovulation & CL Cycle Development CL Formation Function Cow, ewe, Long Spontaneous Spontaneous Spontaneous sow, mare rats, mice, Short Spontaneous Spontaneous Induced hamsters (4 days) (prolactin) rabbit, cat, Induced Spontaneous Induced Induced mink, ferret, (LH surge) otter, alpaca
  21. 21. Estrous Cycle HormoneLevel Progesterone (P4) Estradiol (E2) Day of Estrous Cycle New CL Forming Mature CL Present Fol. Size & CL Size
  22. 22. Methods of Estrus DetectionMethods of Estrus Detection Causes of AnestrusCauses of Anestrus Tail-painting & use of chalk Use of closed circuit television female activity changes Progesterone tests Vaginal probes Use of teaser animals Chin-male devices Heat-mount detectors
  23. 23. Atresia CL CA Ovulation CL Days Relative to the Gonadotropin Surge 0 1 2 3 4 5 6 7 8-1- 2- 3- 4- 5- 6-7 LH FSH PGF2α Estradiol Progesterone Metestrus DiestrusProestrusDiestrus Estrus 11 The estrous cycle may be divided into several phases based on behaviour changes or structural changes in internal & external genitalia.
  24. 24. Atresia CL CA Ovulation CL Days Relative to the Gonadotropin Surge 0 1 2 3 4 5 6 7 8-1- 2- 3- 4- 5- 6-7 LH FSH PGF2α Estradiol Progesterone Metestrus DiestrusProestrusDiestrus Estrus Follicular Phase ProestrusProestrus • Follicle enlarges • Estrogen increases • Vascularity of the female reproductive tract increases • Endometrial glands begin to grow • Estrogen levels peak 22
  25. 25. EstrusEstrus • Allows male to mount • Estrogen decreases • LH surge occurs • Ovulation 24-48 h after surge of LH • Uterine motility high with contractions moving toward oviduct • Sperm transport is optimal • Cervical mucus volume increases Follicular Phase33
  26. 26. Atresia CL CA Ovulation CL Days Relative to the Gonadotropin Surge 0 1 2 3 4 5 6 7 8-1- 2- 3- 4- 5- 6-7 LH FSH PGF2α Estradiol Progesterone Metestrus DiestrusProestrusDiestrus Estrus Luteal PhaseLuteal Phase MetestrusMetestrus • Estrogen low • Ovulation in cow • Corpus hemorrhagicum present • Uterus  Contractions subside  Endometrial glands continue to grow and become coiled  In cattle bleeding occurs • FSH increases  Triggering growth of follicles 44
  27. 27. Atresia CL CA Ovulation CL Days Relative to the Gonadotropin Surge 0 1 2 3 4 5 6 7 8-1- 2- 3- 4- 5- 6-7 LH FSH PGF2α Estradiol Progesterone Metestrus DiestrusProestrusDiestrus Estrus Luteal PhaseLuteal Phase DiestrusDiestrus • Progesterone high • FSH  Increases at some point to cause growth of ovulatory follicle • Uterus  Secrets fluid but volume gradually decreases  Contraction stop  CL regresses at the end of this period if female is not pregnant due to PGF release 55
  28. 28. Before heat (6-10 h) Hours from the start of estrus HoursHours 00 66 99 1818 2424 2828 Egg released Life of egg (6-10 h) Standing heat (18 h) After heat (10 h) Estrus in cow and associated featuredEstrus in cow and associated featured
  29. 29. Approximate Values for Selected Reproductive Events in Female Domesticated Mammals SpeciesSpecies Length of cycle (days) Duration of estrus (hours) Approximate time of ovulation Normal breeding season CowCow Mean=20.5 Range 17 - 23 Mean < 10 Range 1 - 24 30 h after beginning of estrus All year BuffaloBuffalo Mean=21 Range 18 - 22 Mean < 15 Range 4 - 24 32 h after beginning of estrus All year MareMare Mean=21 Range 12 - 35 Mean=120 Range 24 - 240 Near end of estrus Spring & summer EweEwe Mean=16 Range 12 - 19 Mean=30 Range 20 -48 26 h after beginning of estrus Fall (variable with breed) DoeDoe Mean=20 Range 16 - 22 Mean=40 Range 24 - 72 On 2nd day of estrus Fall SowSow Mean=20 Range 16 - 22 Mean=48 Range 24 - 90 36 h after beginning of estrus All year
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ESTROUS CYCLE: Reproductive cycle of female, generally defined as period from one estrus to the next. Two phases: Follicular Phase Luteal phase TYPES OF ESTROUS CYCLE

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