Lecture 14: Sexual Behaviora. General BehaviorAnimal Science 434Reproductive Behavior• Very strong drive and can take precedenceover other activities• Purpose» Promote copulation» Assure sperm and oocyte meet• Goal is to achieve pregnancy and parturitionStages of Reproductive Behavior• precopulatory• copulatory• post copulatoryPrecopulatory Stage• Search for sexual partner» in female, generally limited to estrus• increased physical activity• In primates can occur at any time» in male can occur at any time» involves all of the senses• sight• smell• hearing• tactileSearch For PartnerSearch for PartnerSearch for PartnerSearch for PartnerPrecopulatory Stage (cont.)• Courtship» species specific events» sniffing of the vulva by male» urination by the female» flemen lip curl» chin resting on female rump» increased phonation» male checks for female lordosis» human• eye contact, touching, detection of pheremonesUrinationLordosisWinkingof theVulvaSniffing the VulvaBiting To Check For LordosisUnresponsive MareSniffing the VulvaChecking for LordosisSniffing VulvaChin RestLordosis and MountPhonation of ElkPhonation of ElkHuman CourtshipSight, eye contact, touch, pheremonesPrecopulatory Stage (cont.)• Search for sexual partner• Courtship• Sexual arousal» Female• Lordosis• Presents hindquarters to male» Male• Erection• Penile protrusionCopulatory Behavior• Mounting• Intromission• EjaculationCopulatory Behavior (cont.)• Varies among species» short copulators (1 - 3 seconds)• bull• ram» sustained copulator (5 - 20 minutes)• boar» intermediate (20 to 60 seconds)• stallionShort CopulatorShort CopulatorShort CopulatorCopulatory Behavior (cont.)• Varies among species» short copulators (1 - 3 seconds)• bull• ram» sustained copulator (5 - 20 minutes)• boar» intermediate (20 to 60 seconds)• stallionSustainedCopulatorSustained CopulatorCopulatory Behavior (cont.)• Varies among species» short copulators (1 - 3 seconds)• bull• ram» sustained copulator (5 - 20 minutes)• boar» intermediate (20 to 60 seconds)• stallionIntermediate CopulatorPostcopulatory Behavior• Male» Dismounting» Refractory period - all males have this• time when copulation will not occur• Dependent on:– Species dependent– sexual rest prior to copulation– age of male– degree of female novelty– number of previous ejaculates• for semen collection try to minimize» Memory• a bad experience will carry over• Female - will often mate again immediatelyEndocrine Effects on SexualBehavior• Prenatal steroid exposure» Feminization» Masculinization (defeminization)• Postnatal Behavior» castrated female• no steroids - no estrus behavior• plus estradiol - estrus behavior• plus progesterone and estradiol - maximum estrusbehavior• plus testosterone - male-like behaviorSexual Behavior (cont.)• Postnatal Behavior» castrated male• no steroids - decreased sexual behavior• plus testosterone - sex behavior restored• plus dihydrotestosterone - decreased sex behavior• plus estradiol - sex behavior restoredAromatizationTestosteroneDihydrotestosteroneEstradiolaromataseSexual Behavior (cont.)• both male and female sexual behavior isdependent on estradiol receptors in brainControl of Reproductive Behavior• Sensory systems» Olfactory, visual, auditory, tactile• Hypothalamus» Estradiol receptors, increase response to sensoryneurons• Midbrain» Signals from hypothalamus» Speeds up nerve impulses• Medulla» Coordinates lordosis and mounting• Spinal Chord» Sends signals to specific musclesSensory Inputs forReproductive Behavior• specific importance varies with species• olfaction» pheromone• volatile substance which elicit specific behavior in therecipient• males produce– boars– humans• females produce during estrus– dogs and rats can sense cow pheromones• flehmen responseVomeronasalOrganVomeronasal OrganNasopalatine DuctFluidsFluidsSensory Inputs forReproductive Behavior (cont.)• Auditory» cows bellow» sows grunt» good for long-range signaling• Visual» posturing» males observing other males or females mounting» valuable for close encountersSensory Inputs forReproductive Behavior (cont.)• Tactile» biting on neck or whithers of mare» chin resting on cow» boar nudging of sow flank» final stimulus before copulation» leads to erectionErection, Emission and Ejaculation• Erection» Vasodilatation, inhibit vasoconstriction, relaxretractor penis muscle• Emission» Contraction of cauda epididymis and vas deferens• Oxytocin from posterior pituitary• Sympathetic neurons» Release of accessory gland fluid• Sympathetic neurons• Ejaculation» Contraction of smooth and striated musclesHomosexual Behavior• common in farm animals• useful to detect when females in heat» selection by man may have enhanced this• can collect bulls off of other bulls as
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