动物采精方法.docx
《动物采精方法.docx》由会员分享,可在线阅读,更多相关《动物采精方法.docx(12页珍藏版)》请在冰豆网上搜索。
动物采精方法
SemenCollection
Therearethreecommonly-usedtechniquesforcollectingsemen:
useofanartificialvagina,digitalmanipulation,andelectroejaculation.Thetechniqueuseddependsonthespeciesbeingcollectedandthedispositionoftheindividualmale.
TheArtificialVagina
Artificialvaginas(AV'stotheinitiated)areusedtocollectsemenfrommanyspecies,mostprominentlycattleandhorses,butalsosheep,goats,rabbitsandevencats.
PrerequisitestouseofanAVarethatthemalebeconscious,notsignificantlyfrightenedofpeople,andmoreinterestedinejaculatingthaninkillinghumans.
AnAVusesthermalandmechanicalstimulationtostimulateejaculation.Asshownintheimagetotheright,anAViscomposedofatubewithanouterrubberliningthatwillholdwater,intowhichisplacedaninnerlinerthatislubricatedjustpriortouse.Theouterlinerisfilledandpressurizedsomewhatwithwaterat42-48degreesCelsius.ShownbelowareAVsdesignedforusewithbulls(bottom)andrabbits(top).TheapparatusinthemiddleisatypeofAV,usuallycalledadirectorcone,whichisusedtocollectsemenfromdogs.
Tocollectsemen,themaleisallowedtomountandthepenisisdivertedintotheAVwhereheejaculates.ItisbesttoallowthemaletothrustintotheAVratherthantryingtoslidetheAVontothemale'spenis.Whatthemalemountsdependsonhisspeciesandtemperment.
Femalescanbeused,butunlesstheyareinestrus,theyrarelyenjoyparticipatingintheprocess,whichcaneasilyleadtoinjuryofanyandallofthoseinvolved.AnotherproblemwithusingafemaleasateaseristhatifyoumisswiththeAV,thefemalecouldbebredorpossiblytransmitvenerealdiseasetothemale.Forcollectingsemenfrombulls,atrainedsteerisusuallyused.Inthecaseofstallions,aphantom("dummy")isapopularchoiceforamount.
DigitalManipulation
Manymalescanbeinducedtoejaculatebyapplyingpressureandmassagetothepenis.Afterthemalebecomesaroused,adirectorconeofsometype,attachedtoacollectiontube,isslippedoverthepenistofacilitateharvestingthesemen.
Thistechniqueiscommonlyusedforcollectingsemenfrompigsanddogs.Aninitialtrainingperiodcanbehelpful,andhavingafemaleinestrustoarousethemaleoftenisuseful,particularlywhenthemaleisshy.
Anothertypeofmessageusedoccasionallywithbullsistostroketheampullae(terminalvasdeferens),seminalvesiclesandprostateglandthroughthewalloftherectum;inalmostallcases,thebullmustberestrainedstandinginachuteandsedatedtoallowrelaxationandextrusionofthepenis.Inconjunctionwithaurethralcatether,onecanobtainasterileejaculateusingthistechnique.
Semeniscollectedroutinelyfromchickensandturkeysusingaformofdigitalmanipulation.
Electroejaculation
Electroejaculationinvolvesapplyingaseriesofshort,low-voltagepulsesofcurrenttothepelvicnerveswhichareinvolvedintheejaculatoryresponse.Itsoundslikeanextremelyunpleasantexperience,butdoesn'tseemtocausemuchdistressinbulls(althoughtheydoneedtobesecurelyrestrained),andisconductedunderanesthesiainmanyspecies.
Electroejaculationcanbeusedwithalmostanymammal.Withfewexceptions,electroejaculationistheonlytechniqueusefulforcollectingsemenfromwildanimals,inwhichcasethemaleisanesthetizedpriortotheprocedure.
Anotheradvantageofelectroejaculationisthatitdoesnotrequireamountanimal,andcanbeappliedinthefieldusingabattery-poweredunit.Finally,electroejaculationcanbeusedtoobtainsemenfromanimalsthatarephysicallyincabableofmountingduetomusculoskeletaldiseaseorinjury.Itisusedforcollectingsemenfromquadrapelegicorparapelegicmenwhodesireachildbutcannotejaculateduetospinalcordinjury.
Withbulls,wherethereisabundantexperiencecollectingsemenbybothartificialvaginaandelectroejaculation,thesamplescollectedusinganelectroejaculatorusuallyhavealargervolume(duetoexcessiveaccessoryglandsecretion)andalowernumberofsperm.
Threepiecesofequipmentarerequiredforelectroejaculation.Theelectroejaculatoritselfisapowersupplywithrheostatstocontroltheamplitudeofthedeliveredcurrentandlotsofcircuitrytopreventaccidentalelectrocution.Second,oneneedsacollectiontube,usuallyattachedtoalatexrubbercone("lovingcup")inwhichtocollectthesemen.Finally,thepulsesofcurrentareappliedthroughanelectroejaculatorprobe.Theprobeisinsertedintotherectumsuchthattheelectrodesliewithinthepelviccavity.
Olderprobeshadcircularelectrodes,whichoftencausedundesirablemusclecontractions;probeswithparallelelectrodesononesideminimizethisproblem.Threeprobesareshownbelow-theupperoneisacommercialproductforbullsandthelowerprobeswerehand-madeforusewithsmallleopards(middle)andferrets(bottom).
Successfulelectroejaculationofananimaldemandsskill.Itisnotsimplyamatterofpunchingbuttonsandturningknobs,butrequiresfinesseindeterminingthepropertimingandamplitudeofpulsestoapplytoagivenmale.
SemenCollectionfromBulls
AlargemajorityofdairycowsintheUS,CanadaandEuropeancountriesareartificiallyinseminated.Artificialinseminationofbeefcowsisalsopopular,particularlyinpurebredherds.TheadvantageofAIovernaturalserviceisthatitfacilitatesrapidgeneticimprovementbyallowinguseofonlythetopbulls.Somebullshavesiredmorethan100,000offspringviaAI.
Semenismostcommonlycollectedfrombullsinbullstudsusinganartificialvagina,asdescribedbelow.Electroejaculationisanalternativemethodusedwithbullsthatcannotmountoraretoofractiousforeasyhandling(e.g.rangebulls).Finally,semencanbecollectedbymessageoftheseminalvesiclesandampullaeperrectum.
SemenCollectionviaArtificialVagina
SemencollectionfrombullsusinganAVrequiresthreepeople:
onetohandletheteaseranimal,onetocontrolthebullandonetocollectthesemen.Itisimportantthatthecollectionareahavenon-slipflooringtoavoidinjuriesandbecauseejaculationmaybeinhibitedifthebullisnervousabouthisfooting.Bullsareheavyandshouldhaveregularhoofcare.Poorhoofconditioncaninhibitthebullfrommountingorcausepainwhendismounting.
Asteerismostcommonlyusedasateaserandmountanimal.Femaleteasersarenotrecommendedbecauseofthepotentialriskofintromissionandspreadingofvenerealdisease.Theteasershouldbeacalmanimaloftheappropriatesizeforthebullbeingcollected.
Thebackandrearquartersoftheteaserarewashedwithadisinfectanteverycollectionday.Itisalsocommonfortherearquarterstobeclippedroutinely.Thebull'spreputialhairshouldbeclippedinpreparationforusingtheAV.Thesesanitaryprecautionsareintendedtominimizemicrobialcontaminationofthesemenbeingcollected.
Forcollection,theteaserispositionedstraightinfrontofthebullformounting.Oftentimes,ithelpstoarousethebullifthesteerisledaroundthecollectionarenawiththebullbehind,thenstoppedabruptly,similartothebehaviorofacowinestrus.
Theartificialvaginal(picturedatright)usesthermalandmechanicalstimulationtostimulateejaculation.ThelineroftheAVisfilledwithwaterat42-48degreesCelsius,andtheinnersurfaceislubricatedwithsomethinglikeK-Yjelly.Aninsulatingconeisplacedovertheendfromwhichthecollectiontubeprotrudestoavoidsubjectingthesementotemperatureshock.
Falsemountingisaneffectivewaytosexuallystimulatethebull.Providingtwofalsemountswithtwominutesofactiverestraintandoneadditionalfalsemountmaximizesspermcellnumbers.FinalpreparationsaremadetotheAVbetweenthesecondandthirdfalsemounts.ProperconstructionoftheAVisimportanttoavoiddamagingthebull'spenisandtoavoidstressingspermcells.
SuccessfulsemencollectionwithanAVdependsonthebullbeingcomfortablearoundpeople,andtheyneedtobetrainedtousetheAV.However,bullsarebiganddangerous,andpersonnelsafetyshouldbeemphasizedconstantly.Mostbullsinartificialinseminationcentershaveanoseringinstalledasavaluableandhumanemeansofphysicalcontrol.Bullsundergoingsemencollectionshouldbehalteredandoneshouldnevertieabullupbytheirnosering-ifstartled,thencanripitoutwhichisnotonlyquitetraumaticbutyieldsananimalthatmaybeexceptionallydifficulttocontrol.Duringcollection,thepersonhandlingtheAVmustremainawareofwheretheirfeetarerelativetothebull.Astheanimalejaculates,itiscommonforhimtojumpforward.Toavoidfootinjury,collectorsshouldwearbootswithsteeltoes.
Inartificialinseminationcenters,bullsaretypicallycollected2or3timesperweek,with2or3ejaculatespercollectionday.Thefollowingimagesdepictroutinesemencollectionfromabull.
Falsemountingtoarousebull
Anerectpenisindicatesarousal
CollectorreadywithAV
CollectordivertingpenistotheAV
SemenEvaluation
Semenshouldbeevaluatedgrosslyforabnormalappearance.Thepresenceofsmall"clots"orbloodcanindicatesuchconditionsasseminalvesiculitis.
Parameter
NormalValues
Ejaculatevolume
5ml(range1-15ml)
Spermconcentration
1200million/ml(range300-2500million/ml)
Totalspermperejaculate
Typically4-5billion
Progressivemotility
Greaterthan30%
Morphology
Greaterthan70%normal
SemenCollectionfromDogs
Semeniscollectedfromdogsforbreedingsoundnessexams,aswellasforartificialinsemination.Semencollectedfori