Animal Science 434Reproductive Cycles in the FemaleTerminology• Estrus is a noun.– The cow is displaying estrus.• Estrous is an adjective.– The length of the estrous cycle is 21days.• Oestrus and Oestrous– British and European spellings• Estrus and Heat are synonymousTerminology (cont.)• Anestrus– When the female is not having repeatedestrous cycles.Types of CyclicityPolyestrusPolyestrusRelative E2J F M A M J J A S O N D• Queen• Cow• SowTypes of CyclicitySeasonallyPolyestrusSeasonallyPolyestrusShort day breeders(Fall)Long day breeders(Spring)Relative E2J F M A M J J A S O N DRelative E2J F M A M J J A S O N DType of CyclicityMonoestrusMonoestrusDog Wolf BearRelative E2J F M A M J J A S O N DAverage Reproductive CyclesSpecies Length of Length of Ovulation Length ofEstrous Cycle Estrus Pregnancycow 21 days 18 hr 11 hr after 282 days polyestrus end estrusewe 17 days 29 hr near end 148 daysseasonal (fall) estrussow 21 days 48-72 hr 35-45 hr 115 days polyestrus after startestrusmare 21 days 4-8 days 3-6 day of 335 daysseasonal (spring) estrus polyestrus (1-2 daysbefore end ofestrus)Average Reproductive CyclesSpecies Length of Length of Ovulation Length ofEstrous Cycle Estrus PregnancyBitch 6 months 9 days 4 - 24 days 63 daysafter start ofestrusQueen 17 days 9 days Induced 63 daysVariation in Cycle TypesExample Type of Follicular Ovulation & CL Cycle Development CL Formation FunctionCow, ewe, Long Spontaneous Spontaneous Spontaneoussow, marerats, mice, Short Spontaneous Spontaneous Inducedhamsters (4 days) (prolactin)rabbit, cat, Induced Spontaneous Induced Inducedmink, ferret, (LH surge)otter, alpacaCADays Relative to the Gonadotropin Surge0 1 2 3 4 5 6 7 8-1- 2- 3- 4- 5- 6-7LHFSHPGF2 αEstradiolProgesteroneMetestrus DiestrusProestrusDiestrus EstrusCLOvulationCADays Relative to the Gonadotropin Surge0 1 2 3 4 5 6 7 8-1- 2- 3- 4- 5- 6-7LHFSHPGF2 αEstradiolProgesteroneMetestrus DiestrusProestrusDiestrus EstrusCLOvulationCADays Relative to the Gonadotropin Surge0 1 2 3 4 5 6 7 8-1- 2- 3- 4- 5- 6-7LHFSHPGF2 αEstradiolProgesteroneMetestrus DiestrusProestrusDiestrus EstrusCLOvulationCADays Relative to the Gonadotropin Surge0 1 2 3 4 5 6 7 8-1- 2- 3- 4- 5- 6-7LHFSHPGF2 αEstradiolProgesteroneMetestrus DiestrusProestrusDiestrus EstrusCLOvulationCADays Relative to the Gonadotropin Surge0 1 2 3 4 5 6 7 8-1- 2- 3- 4- 5- 6-7LHFSHPGF2 αEstradiolProgesteroneMetestrus DiestrusProestrusDiestrus EstrusCLOvulationCADays Relative to the Gonadotropin Surge0 1 2 3 4 5 6 7 8-1- 2- 3- 4- 5- 6-7LHFSHPGF2 αEstradiolProgesteroneMetestrus DiestrusProestrusDiestrus EstrusCLOvulationFollicular PhaseProestrus• Preovulatory follicleenlarges• estrogen increases• vascularity of thefemale reproductivetract increases• endometrial glandsbegin to grow• estrogen levels peakCADays Relative to the Gonadotropin Surge0 1 2 3 4 5 6 7 8-1- 2- 3- 4- 5- 6-7LHFSHPGF2 αEstradiolProgesteroneMetestrus DiestrusProestrusDiestrus EstrusCLOvulationFollicular PhaseEstrus• allows male to mount• estrogen decreases• LH surge occurs• ovulation 24-48 hr aftersurge of LH• uterine motility highwith contractionsmoving toward oviduct• sperm transport isoptimal• cervical mucus volumeincreasesCADays Relative to the Gonadotropin Surge0 1 2 3 4 5 6 7 8-1- 2- 3- 4- 5- 6-7LHFSHPGF2 αEstradiolProgesteroneMetestrus DiestrusProestrusDiestrus EstrusCLOvulationLuteal PhaseLuteal PhaseMetestrus• estrogen low• ovulation in cow• corpus hemorrhagicumpresent• uteruscontractions subsideendometrial glandscontinue to grow andbecome coiledin cattle bleedingoccurs• FSH increasestriggering growth offolliclesCADays Relative to the Gonadotropin Surge0 1 2 3 4 5 6 7 8-1- 2- 3- 4- 5- 6-7LHFSHPGF2 αEstradiolProgesteroneMetestrus DiestrusProestrusDiestrus EstrusCLOvulationLuteal PhaseLuteal PhaseDiestrus• progesterone high• FSH Increases at somepoint to causegrowth of ovulatoryfollicle• Uterus secrets fluid butvolume graduallydecreases contraction stop CL regresses at theend of this period iffemale is notpregnant due toPGF releaseCharacteristics of Estrous CyclesCow Ewe Sow MareEstrous cycle (days) 21 17 21 21Proestrus (days) 3-4 2-3 3-4 2-3Estrus 12-18 hr 24-36 hr 48-72 hr 4-8 daysMetestrus (days) 3-4 2-3 2-3 2-3Diestrus (days) 10-14 10-12 11-13 10-12Hormonal Changes in the Bitch0 1020-20ProestrusEstrusAnestrusFSHE2LHProgesteroneDaysOvulation0 20 40-20Day of Metestrus60 80ProgesteroneE2ProlactinHeat20 dayMetestrus IMetestrus II 70 daysParturitionHormonal Changes in the Queen4 8 12 16P4E2WeeksEstrus4 8 12 16 20P4E2(9 days)Queen in Estrus(no mating)Hormonal Changes in the Queen4 8 12 16P4E2ProestrusProestrusEstrus4 8 12 16 20P4E2WeeksQueen in Estrus(no mating)(8 days)Hormonal Changes in the Queen4 8 12 16P4E2ProestrusProestrusEstrus4 8 12 16 20P4E2PregnancyParturitionLactationWeeksQueen in Estrus(no mating)MatingMatingCauses ofAnestrusPregnancyPresence of OffspringSeasonStressPathologyNutritionGestational AnestrusGestational Anestrus• Progesterone during pregnancy– negative feedback• After parturition anestrus continues– progesterone exposure duringpregnancy– hypothalamus• Lacks estradiol positive feedback• allows time for uterine involutionSeasonal AnestrusHorses are long day breeders!Sheep are short day breeders!EstradiolNegativeFeedbackincreasesDecreasedNegativeFeedbackEstradiolEstradiolSeasonal Anestrus• just like entering puberty• silent ovulation++Silent OvulationAnestrusEstrusLactational AnestrusSuckling Effect on LHLactational Anestrus• Suckling• Other offspring factors– visual encounter– olfactory encounter– auditory encounter• Prolactin– inhibits GnRH release– major infertility problem in women whoare not lactatingNutritional AnestrusMenstrual CycleFSHLHEstradiolProgesteroneFollicleOvulationCorpus LuteumCorpusAlbicans2 4 6 8 10 14 16 18 20 22 24 26 28 212AnteriorPituitaryHormonesOvarianHormonesOvaryUterineEndo-metriumRecruitmentSelectionDominanceRecruitmentFSHLHEstradiolProgesteroneFollicleOvulationCorpus Luteum2 4 6 8 10 14 16 18 20 22 24 26 28 212AnteriorPituitaryHormonesOvarianHormonesOvaryUterineEndo-metriumMensesMenses5days5 daysFSHLHEstradiolProgesteroneFollicleOvulationCorpus Luteum2 4 6 8 10 14 16 18 20 22 24 26 28 212AnteriorPituitaryHormonesOvarianHormonesOvaryUterineEndo-metriumFollicular Phase9
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