Principles Of Reproductive Management

http://edis.ifas.ufl.edu/ ( Publisher's URL )
MISSING IMAGE

Material Information

Title:
Principles Of Reproductive Management
Physical Description:
Fact sheet
Creator:
Shearer, J.K.
Publisher:
University of Florida Cooperative Extension Service, Institute of Food and Agriculture Sciences, EDIS
Place of Publication:
Gainesville, Fla.
Publication Date:

Notes

Acquisition:
Collected for University of Florida's Institutional Repository by the UFIR Self-Submittal tool. Submitted by Melanie Mercer.
Publication Status:
Published
General Note:
"published September, 1992"
General Note:
"DS 59"

Record Information

Source Institution:
University of Florida Institutional Repository
Holding Location:
University of Florida
Rights Management:
All rights reserved by the submitter.
System ID:
IR00004740:00001


This item is only available as the following downloads:


Full Text

PAGE 1

PrinciplesofReproductiveManagement1 TheInstituteofFoodandAgriculturalSciencesisanEqualOpportunity/AffirmativeActionEmployerauthorizedtoprovideresearch,educational informationandotherservicesonlytoindividualsandinstitutionsthatfunctionwithoutregardtorace,color,sex,ornationalorigin. FloridaCooperativeExtensionService/InstituteofFoodandAgriculturalSciences/UniversityofFlorida/JohnT.Woeste,DeanJ.K.ShearerandD.W.Webb2Recordsareindispensableintheevaluationof reproductiveperformance.Knowledgeofjustafew basicparameterscanprovidesomeveryimportant cluestoreproductiveproblemareasinherds. 1.Averagedaysopen/calvinginterval 2.Daystofirstbreeding 3.Services/conception 4.OptionintervalRECORDSFORREPRODUCTIVE MANAGEMENTAveragedaysopenistheaveragenumberofdays fromthemostrecentcalvingtoconception. Projectedminimumcalvingintervalispreferredover averagedaysopenbysome;however,theyare measurementsofessentiallythesamething.Calving intervalsaredeterminedforeachcowusingthelast calvingdateandprojectingfromthatdatethedue date.Daystofirstbreedingistheaveragenumberof daysfromthemostpreviouscalvingtofirstservicefor allcowsinthebreedingherd. Thenumberofbreedingsperconceptionissimply thenumberofbreedingsrequiredtoachieve conception. TheOptionIntervalorVoluntaryWaitingPeriod isthenumberofdaysfromthemostpreviouscalving tothetimeinwhichtheherdmanagerdecides(athis option)tobeginre-breeding. Table1liststhereproductiveparametersfora herdwitha14-monthcalvinginterval.By incorporatingthisdataintoalinearmodelstarting withcalvingatdayzeroandendingwiththe succeedingcalving421dayslater(140daysopen+ 281daysgestation)onecanvisualizewhatfactorsmay becontributingmosttodaysopen(Table2).From thismodeldayslostfromdelayedre-breeding,missed heats,and/orfailuretoconceivecanbedetermined. Inthisexampletheoptioninterval(voluntary TableTable1.1.Reproductiveparametersforaherd. AVERAGEDAYSOPEN 140 CALVINGINTERVAL 14 DAYSTOFIRSTBREEDING 83 SERVICES/CONCEPTION 2.5 VOLUNTARYWAITINGPERIOD 60waitingperiod)is60days.Theaveragetime necessarytoobserveheatsintheherdafterthis waitingperiodwillbeequaltoaboutone-halfthe numberofdaysinanormalestruscycle(10daysused inthisexample).Sinceitisobviousthatallcowswill notbeinheatonday61andourDHIrecordstellus thatthe"averagedaystofirstservice"is83we calculatealossof13daysduetomissedheatsprior tothefirstservice.Dayslostduetoafailureto conceiveare31.5basedonservices/conceptionof2.5. The31.5dayfigureiscalculatedbymultiplying21 (numberofdaysinanormalestruscycle)by1.5 whichisthenumberofadditionalservices(afterthe firstone)toachieveconception.Bysummationof theoptioninterval(60days),averagedaystothenext 1.ThisdocumentisFactSheetDS59oftheDairyProductionGuide,publishedSeptember,1992,FloridaCooperativeExtensionService.For moreinformation,contactyourcountyCooperativeExtensionServiceoffice. 2.AssociateProfessor,CollegeofVeterinaryMedicine,andProfessor,DairyScienceDepartment,InstituteofFoodandAgriculturalSciences, UniversityofFlorida,Gainesville.

PAGE 2

PrinciplesofReproductiveManagement Page2 TableTable2.2.Partitionofdaysopenfora14-monthcalvinginterval. Calving 0Days 1stService 83Days Conception 140Days Calving 421Days (14Months) 60Days 10Days-13Days 31.5Days-25.5Days 281Days Voluntary Waiting Missed heats Missed heats Gestationheat(10),dayslostduetomissedheatspriortothe firstservice(13),thedayslostduetoafailureto conceive(31.5),andsubtractionofthistotal(114.5) fromtheaveragedaysopen(140),calculationofdays lostduetomissedheatsbetweenservicesis25.5days. Thegestationperiodof281daysplusthe140days openresultsinatotalof421days(14monthcalving interval).HEATDETECTIONIntheaboveexamplethetotalnumberofdays lostduetomissedheatsis(13+25.5)38.5.Failure toobserveisstillthemajorcauseforextendeddays openinmostherds.Sincethedurationofestrus averages6to12hours,cowsmustbeobservedat least2timesandpreferably3timesdaily.Studies indicatethatanimalsinestrusmayonlystandonce every10to15minutes,consequently,observation periodsshouldlastaminimumof30minuteseach. Inaddition,timeschosenforobservationofcowsin heatshouldbescheduledsoastotakeadvantageof timesinwhichcowswillmostlikelybeexhibiting estrusbehavior.Inotherwords,trytowatchcows duringtimeswhentheyarefreetointeract,notwhen beingfedorcrowded.Otherfactorswhichinfluence thechancesforobservingcowsinheatarethe numberofsexuallyactivecowsavailable,locationof cows,andthetypeofhousingconditions. Finally,theuseofvariousheatdetectionaids (mostcommonlyheatdetectorpatchesandtailhead marks)canbeveryhelpfulparticularlywhenthe numberofmountingcowsinthebreedinggroupis low.Hormonallytreatedheifers,cows,orsteers, fittedwithchinballmarkerswillmarkcowsinornear heatandthishasworkedwellforsomeherds. Studiesindicatethatcowswhichcalvenormally andwithoutcomplicationwillcyclebetween15and 21daysfollowingcalving.Ontheotherhand,cows thatexperiencecalvingdifficulties,disease,orsevere negativeenergyimbalance(metabolicimbalance)may notcycleforthefirsttimeuntil30ormoredaysafter calving.Anythingwhichdelayscyclicactivityretards therateofuterineinvolution(theprocessofthe uterus'sreturntoitsnormalnon-pregnantsize) therebyinhibitingthecow'snaturalmechanismfor clearingorresistinguterineinfectionintheearlypost partumperiod. Finally,Morrowobservedthatsilentestrus occurredin77.1%offirstpostpartumovulations,in 54.4%ofsecondovulations,andin35.8%ofthird ovulations.Thesedifferencesintheexpressionof estrusbehavioralsignsduringthefirstthreeestrus periodsisthoughttoberelatedtopatternsofovarian hormonesecretion.Ingeneral,ittakesabout3to4 postpartumcyclesbeforethenormalintensityof estrusbehaviorisreached. Severalothershavenotedahigherincidenceof silentestrusassociatedwithhighmilkproduction.In someherdsthecauseisquitelikelyassociatedwitha situationof"negativeenergybalance."Thiscondition occursduringthefirst60to90daysoflactation. Simplystateditistheperiodduringearlylactation whenthecow'sfeedenergyintakelagsbehindthat necessarytosupporttheenergyexpendedtoproduce milk.Thedairycowcompensatesforthisincreased metabolicdemandbydrawingonbodyreserves. Dependingonthecow'sbodycondition,andseverity oftheimbalance,evidenceofcyclicactivitymaybe significantlyreduced.

PAGE 3

PrinciplesofReproductiveManagement Page3 Inthesouthernstatesheatstressprovidesyetstill anothercomplicationtoestrusdetectionefficiency. Evenso,consideringthemultitudeoffactorsaffecting heatdetectionitisstillreasonabletoexpecta70% heatdetectionrate.Thiscoupledwithre-breedingat 50dayspost-calvingmakesagoalof65to70average daystofirstbreedingachievable.Assumingno seriousconceptionproblems(breedings/conceptionof 2.5orless)thena12.5to13monthcalvinginterval (105to115daysopen)isattainable.Theseare realisticaswellasprofitablereproductivegoalsfor mostherds.SPECIFICHEALTHCONCERNSIN REPRODUCTIVEHEALTHMANAGEMENTHealthconcernsinreproductivemanagement includepropercareofthedrycow,calvingareaand calvingproblems,andpostcalvingreproductive disorders.DryCows/CalvingCowsDrycowsshouldbeneithertoofatnortoothinas theyapproachcalving.Overconditionedcowsare subjecttoahigherincidenceofcalvingdifficulties, metabolicdisorders,andreproductiveproblems. Theyhavemoreretainedplacenta,endometritis, cysticovariandiseaseandusuallycyclelaterfollowing calving.Theoverlythincowislikelytobeunableto sustainhighlevelsofmilkproductionduringearly lactationbecauseofinadequatebodyreserves.The developmentofseverenegativeenergybalanceis believedbymanytobethemostimportantnutritional determinantinthereproductivehealthofthe postpartumcow. Thepropercalvingenvironmentlimits post-calvinguterineinfections,mastitisandthe incidenceofneonatalcalfdisease.Well-drainedgrass lotsorpasturesarepreferredandwhenpossiblethese shouldbelocatedtoaccommodatefrequent observationofcowsnearcalving. Theincidenceofdystocia(difficultbirth)incattle isreportedtobe3to4percent.Normaldeliverycan beimpairedbyanimproperlypositionedcalf,an extremelylargecalforundersizedcow,oracowwith milkfever.Wheneverlaborisprolongedthecow shouldbeexamined.Goodhygieneandlubricationof thearmsandotherinstrumentsareessentialsfor properexaminationandassistancewithcalving difficulties.Post-calvingReproductiveDisordersReproductivedisordersindairycattlearecaused byinfection,disease,andinabilitytoconceive.RetainedPlacentaOneofthemostcommonpost-calving complicationsisretainedplacenta.Theincidencecan be30%orhigher,butinmostherdsislessthan10%. Theplacentaisconsideredtoberetainedwheneverit hasnotbeenexpelledwithin12hoursfollowingbirth. Causesforretainedplacentaaremany:hormonal, nutritional,abortion,prematurebirth,twinning, dystocia,andmilkfever.Theresultofretained placentaisuterineinfection,delayeduterine involution,andsubsequentreducedfertility. Ideasonmanagingretainedplacentaarevaried. Onethingthereisagreementon,however,isthat retainedplacentaltissuesshouldnotbemanually removed.Severalresearchershaveattemptedto evaluateintrauterine(intotheuterus)versussystemic therapyforretainedplacentaconditions.Theyhave foundthattheeffectivenessaswellasabsorptionof antimicrobialagentsisinhibitedbythepresenceof excessiveuterinelochia(uterinecontents)anddisease oftheuterinelining(endometrium).Therefore systemicadministrationofantibioticsmaybesuperior tointra-uterineinfusiontechniquesformanyofthese infections.Inanycase,cowswithsystemicsignsof illnessassociatedwithretainedplacenta(suchasfever ortoxemia)shouldbetreatedaccordingly. Intra-uterinetreatmentaloneisnotlikelytobe effective.EndometritisEndometritis(uterineinfection)resultsfroma varietyofcomplicationsassociatedwithcalving.In fact,somestudiesindicatethatinfectionisalmost universalintheearlypost-calvingperiodevenincows thatcalvenormallyanddonotretaintheirplacentas. Similartoretainedplacenta,theuseofantimicrobial infusionshaveshownmixedresultsinthetreatment ofuterineinfections.Studiesoninfusionagents whichhaveatendencytobeirritatingtothe endometriumhavebeenshowntoalterthelengthof theestruscycleincows.Inonestudyinfusionof diluteiodineonday15oftheestruscyclewas observedtoprolongthecycle,whereas,infusionon day3or4shortenedthecycle.Incontrast,the

PAGE 4

PrinciplesofReproductiveManagement Page4 infusionofnon-irritatingsubstanceshadnoeffecton lengthoftheestruscycle. Inrecentyearswiththediscoveryofprostaglandin newmethodsforuterinetherapyhaveemerged. Thesecompoundsworkbycausingluteolysis(rapid resorptionofthecorpusluteum),relaxationofthe cervixandexpulsionoftheuterinecontents.Inthe presenceofamaturecorpusluteumtheresponseto treatmentisdramaticandrapidcausingthecowto comeintoheatwhichresultsintheevacuationof uterinecontentsusuallywithin2to5daysfollowing administrationofthedrug.AnestrusAnestrusistheabsenceofobservedheat. Primarycausesare:failuretoobserve,pregnancy, cysticovariandisease,uterineinfection(pyometra), andstressesassociatedwithextremeheatandhigh milkproduction.Inmostherds,betterthan90 percentofcowsnotpregnantwillbecycling.Cows notobservedinheatby40dayspost-partumshould beexamined.Palpationofanestruscowscanbea valuableheatdetectionaid.InfertilityInfertilityincowsisusuallyassociatedwithoneor moreofthefollowing:1)diseaseoftheovaryand/or uterus;2)failureofthefertilizedeggtoimplant;3) deathoftheembryo;4)faultyheatdetectionand inseminationtechnique.Ahighpercentageofthe infertilitycasescommonlyobservedindairycowsare aresultofimplantationfailureassociatedwithuterine infectionsand,inthesouthernstatesparticularly,heat stress.Whensuchproblemsariseathorough examinationofaffectedcowsisindicated.Some informationisavailablewhichindicatesthatthe practiceofpost-breedinginfusionishelpfulinrepeat breedercows.Thiscanbeconvenientlyperformedat 12to24hoursfollowingbreeding.Careshouldbe takentoutilizeanon-irritatingtypeofinfusion producttoavoidthepotentialeffectsofalteringthe normalestruscycleasdescribedearlier. Also,theuseofGonadotropicReleasing Hormone(GnRH),administeredatthetimeof breeding,hasbeenshowntoincreasetheconception rateofrepeatbreedercows.TrichomoniasisandVibriosisInherdswherebullsareused,thevenereal diseases,trichomoniasisandvibriosis,mustberuled outaspredisposingcausesofinfertilityproblems. Trichomoniasisischaracterizedbyearlydeathofthe embryowhichisexhibitedinthecowasinfertility. Lessfrequently,abortionsandsevereuterine infectionsmayoccur.Cowsmostcommonlybecome infectedwhenbredbyinfectedbulls.Theperiodof infertilitycontinuesuntilimmunitydevelops.This variesbetweencowsbutisusually2to6months. Bullsshownoevidenceofinfection.Thecontrolof trichomoniasismaybeaccomplishedby:1) eliminatingtheinfectedanimals;2)breedingcowsby artificialinsemination;3)separationofinfectedand exposedanimalsfromtheherd;4)allowingaperiod ofsexualrestforcowsbredtosuspectorinfected bulls;5)selectivecullingofinfectedandsuspectbulls andintroductionofyoungvirginbullsthathavebeen testedandareknowntobefreeofthedisease. Vibriosisischaracterizedbytemporaryinfertility incowswiththeprimaryclinicalsignbeingareturn toestrus.Cowswhichbecomeinfectedwilldevelop immunity;however,itisshort-lived.Thereisa vaccineavailableforuseandinherdswherebull breedingispracticed,vaccinationisadvised.The vaccinemustbegivenatleastonceandpreferably twiceannually.Amoreefficientmethodforcontrol ofvibriosisistheabsoluteuseofartificial insemination. Table3liststheprimarydiseasesaffecting reproductionandsuggestssomecontrolprocedures. Thesediseasescanhaveadevastatingimpactwhen theyoccur.Agoodvaccinationprogram incorporatingthesevaccinesischeapinsuranceanda worthyinvestment. Insummary,theveterinarianisanimportant componentinthedairyherd'shealthprogram.Just asthedairymonitorsitsproductionandmakes necessaryadjustmentsforimprovement,somustthe veterinarian.Recordsarethemeansbywhichthis canbeaccomplished.Anyprogramwhichdoesnot continuallyandregularlyre-evaluateitsprogress,may

PAGE 5

PrinciplesofReproductiveManagement Page5 notprogress.Thepotentialforlossfrominefficient reproductioninthedairyherdjustifiesmakingasolid commitmenttowardachievementofoptimal reproductivegoals. TableTable3.3.Diseasesaffectingreproductiveperformanceandsuggestedcontrolprocedures. Reproductivedisease Controlandpreventionmeasures Brucellosis Vaccination. Purchasereplacementsonlyfromadiseasefreeherd. Disposeofabortedfetusesandplacentasproperlywithoutcontaminating premises. Slaughterinfectedanimals. Leptospirosis Annual(orpreferably2xyearly)vaccination,butseveralspeciesoforganisms areinvolved. Controlrodentpopulation. Fencecattlefromstagnantwaterwhereurinefromcarriercattleorwild animalsmayaccumulate. Vibriosis A.I.usingantibiotic-treatedsemenwillgivealmost100%control. Disposeofinfectedbullsandcows. Infectedbullsmaybetreatedwithantibiotics,butrecoveryisslow.With sexualrest,manycowsrecoverspontaneously. Trichomoniasis UseA.I.toprevent. Treator,preferably,eliminateinfectedanimals. IBR Vaccinateonlycalvesandnonpregnantadultsusingmodifiedlivevirus.Live viruscancauseabortioninpregnantanimals. Intranasalvaccineorkilledvirusvaccine(safeforpregnantanimals). BVD Vaccinateonlycalvesandnon-pregnantadultsusingmodified-livevirus vaccine. Killedvirusvaccineissafeforpregnantanimals.