Sexual Behavior to Parturition PDF

1 2 Importance of Sexual...

1 2 Importance of Sexual Behavior bring the individual together (male and female ). Conservation of the species and for the continuity of their life. Synchronize the activities of male and female ( ova and sperm). Produce a new progeny (selective) Sexual S e x u a l be h a v i o u r i n v o l v e s n o t o n l y t h e a c t o f ma t i n g, bu t a l s o a l l t h o s e e l e me n t s o f c o u r t s h i p, d i s pl a y , mo t o r species a c t i v i t i e s a n d po s t u r e s wh i c h h a v e a u n i t y wi t h c o i t u s t o Behavior a c h i e v e f e r t i l i z a t i o n a n d pr e gn a n c y. It is a species-specific behaviour Ea c h S pe c i e s h a s s pe c i a l s e x u a l be h a v i o u r ( S pe c i e s - s pe c i f i c ) a n d wi t h i n s pe c i e s t h e r e i s d i f f e r e n c e s be t we e n ma l e a n d f e ma l e. 3 4 Importance of Sexual Behavior Important in raising livestock species: 1. Sheep, swine, beef cattle – reproductive Adult male Factors for expression performance important and female 1.Physiological Numbers 2.Environmental Genetic improvement sexual 3.Psychological 2. Dairy cattle – time of birth is important behavior Cumulative milk production depends on: 3. Companion animals – producing valuable offspring Resolving reproductive problems 5 6  Anatomical Factors Previous Social and Sexual Experience Absence of spine Lack of sexual experience can have a greater influence than hormonal imbalance Inability of intromission Raised in isolation (Lack of socialization) Will not induce ovulation Inhibit sexual behavior Dog do not mount No prior experience, excessive experience, homosexual only experience, or very unpleasant experience can all lead to sexual behavior problems. External environment High temperature Slippery floor Time of day Stress 7 8 Attractiveness of Potential Mate Male to Female ratios Based on innate preferences and past experience Appropriate sex ratios for Direct selection breeding animals are affected Arbitrary mate choice by a number of factors, such as: age, degree of sexual Good Genes development, space and topography, environmental (temperature, etc) and other variables including social circumstances (single or multiple sire grouping). The sex ratio commonly used in major species of farm animals Image courtesy : USDA ARS Image Library 9 10 Adult Hormonal Status Effect of Removal of Gonads Hormones have a permissive role in adult animals. Maintenance of sex drive Normal sexual behavior requires a certain level of hormones. observed after castration Varying administrations of estrogen and progesterone will elicit may be due to secretion of estrous behavior. androgen from the adrenal gland (cortex). Sexual behaviors can be altered by castration The continues sexual activity Experience affects castration effects of the experienced castrates Anatomical problems could be attributed to: Inability to mate 1. Substitute secretion of androgen from the adrenal cortex, and 2. Psychological factor ( learned/acquired habit) 11 12  General hormone effects in males Perinatal hormone influences Sex hormones play an important role in sexual behavior Neonatal androgens “defeminize” males Androgen causes the development and maintenance of the secondary sexual traits of males during adolescence and for activity of mating behaviour beginning from puberty. Androgen can cause the production of pheromones by glands and tissues Testosterone Estrogen 13 14 Central Nervous System Control of Male Sexual Behavior Adrenal Cortex PRIMARY STEROID CORTICOSTEROID PRINCIPAL ACTION HORMONE Mineralocorticoids Aldosterone Help conserve body fluid by acting on kidneys and increasing reabsorption of Na⁺ an water in renal tubules. Glucocorticoids Cortisol Help the body cope with stress by stabilizing blood glucose levels; in large quantities they also inhibit inflammation and the immune system. Androgen Dehydroepiandrosterone A relatively weak androgen, but it’s responsible for the (DHEA) androgenic effects of adrenarche (e.g. early pubic and axillary hair growth, adult-type body odor, ↑ oiliness of hair and skin, mild acne) Potentiated locally via conversion into testosterone and dihydrotestosterone (DHT) in skin and hair follicles A weak estrogen. Can also transform into potent estrogens such as estradiol in certain tissues, thereby 15 16 Central Nervous System Control of Female Sexual Behavior In proestrus, the feedback loop is reversed from negative to positive. G onadotropin Releasing Factor Increased estrogen is responsible for estrus behavior. Luteinizing Hormone Follicle-Stim ulating Horm one The resulting LH surge induces ovulation. 17 18  General hormone that affects in Females 1. GnRH – signal from hypothalamus. Estrogen 2. FSH and LH – released from anterior pituitary gland in cyclic manner. § acts on the development of mammary ducts and sensitize and FSH - responsible for development of ovarian follicles. increase the vascular supply of the uterus. LH- causes ovulation of matured follicle containing the egg. § associated with secretion of pheromones at pro and estrus 3. Estrogen- released from ovarian follicle which developed and become an endocrine gland. Progesterone Has multiple effects: a. Causes behavioral estrus § causes the growth of mammary glands by developing the lobule- alveolar system, and the progestational growth of the uterus. b. Acts in feedback mechanism on the hypothalamus, so that at the proper time, the AP is caused to release LH. 4. After ovulation, ruptured follicle develops a yellow body called corpus luteum which becomes an endocrine gland-secreting progesterone 19 20 Mammalian Estrous Cycle Phases of Estrous Cycle Estrous Cycle PHASES CHARACTERIZATION § Begins at puberty which Ø Initial development follicles influenced by FSH 1. Proestrus Ø Follicles start secreting estrogen to prepare the FOLLICULAR PHASE: continues to occur in a regular reproductive system (high vascularity, thickening of vaginal wall) Short phase - only 20% of cycle pattern when the female is not Period from regression of corpus luteum to pregnant throughout her Ø follicles becoming mature ovulation active reproductive life. Ø behavioural estrus influenced by estrogen Preovulatory follicle 2. Estrus Ø females accepts male Dominant hormone is estradiol (an estrogen) § Poultry – do not show estrous Ø ovulation influenced by LH shortly after estrus in some species. cycle LUTEAL PHASE: § Farm mammals- estrous cycle Ø Corpus luteum becoming function and secreting Long phase - 80% of cycle progesterone has 4 phases- influenced by 3. Metestrus Period from ovulation to corpus luteum Ø Further growth of uterus and progestational changes regression the gonadotropic hormones of Ø Last stage of estrous cycle, if pregnancy occurs. Corpora lutea the AP and the hormone Dominant hormone is progesterone Ø Longest phase of the cycle (between mestestrus and secreted by the ovary. proestrus) Follicle continue to grow and regress during 4.Diestrus Ø CL fully develops would be regressing including the uterus this phase (involution) 21 22 PROESTRUS ESTRUS Begins when progesterone declines Period of sexual receptivity (luteolysis) and ends at onset of estrus Large increase in estrogen Lasts 2 to 5 days stimulates release of LHRH Period of major endocrine transition Progesterone dominance to estrogen FSH decreases due to estrogen and dominance inhibin FSH and LH responsible During or shortly after estrus, “Building Up” ovulation occurs due to major surge in LH Ovarian follicle, with enclosed ovum, increase in size LH levels increase due to LHRH Estrogens absorbed from the follicles into Estrus stops once ovulation occurs. blood stream stimulate increased vascularity and cell growth of tubular genitalia, in preparation for estrus and pregnancy 23 24  METESTRUS DIESTRUS Corpus Luteum Relatively short period of time between predominant estrous cycles during the breeding season of polyestrous animals ↑Increase in progesterone, ↆ – No reproductive activity decrease in estrogen Endometrial lining Prolonged diestrus thickens and uterine CL is fully functional muscles show increased development. High levels of progesterone End with luteolysis 10 to 14 days (Depending on the species of animal) 25 26 SUMMARY OF STAGES ANESTRUS Proestrus= Formation of ovulatory follicle + E2 secretion Long period of inactivity between sexual seasons No regular estrous cycles Estrus = Sexual receptivity + peak E2 secretion Ovaries relatively inactive No follicles or CL Metestrus = CL formation + beginning of P4 secretion Diestrus = Sustained luteal secretion of P4 27 28 Copulation and Ovulation Copulation and Ovulation The female sexual receptivity is closely synchronized with ovulation. The event so timed to effect fertilization of the sperm and the egg. Kinds of Ovulators: Kinds of Ovulators: 2. Spontaneous ovulators 1. Induced or reflex ovulators Example: cows, sows , mare, ewe Example: rabbit and cat Eggs is released at a certain stage of the cycle Females ovulate only in response to mating Copulation is not required for ovulation, the presence of the male of the species stimulate or increase the: If no mating happens, mature ovulation follicles regress. Promptness of ovulation Ovulation can be caused by: Proportion of fertilized eggs ü Mounting of another female Likelihood of successful implantation ü Intromission of instrument ü Genital stimulation 29 30  Sexual Behavior Breeding Strategies Objective: leaving as many surviving offspring to reproduce as possible Competition between males reflects individual fitness – to insure continuation of family, line, Wild Ancestors - Mostly as a point of reference for species comparison to our domestic animals Number of offspring born reflects differences in infant and adult mortality and longevity of species Mating process (copulation) Influences Reproductive Success > Most species ovulate spontaneously > Cat and rabbit ovulation is induced by copulation > Coitus-induced ovulation increases a female’s reproductive efficiency > Coitus can facilitate or hasten ovulation and is important in the utilization of AI > Pregnancy rate with AI is increased if the clitoris is massaged when the insemination is done Helping the reproductive success of relatives (kin selection) > Involves the indirect better-than-nothing strategy increases inclusive reproductive fitness (genetic immortality) > When barren sisters help sister with offspring 31 32 Seasonality Seasonality 2. Domestic Species 1. Most wild mammals of temperate zones are highly seasonal Artificial selection has reduced seasonality in cattle, swine, and dogs Bearing and caring for offspring is extremely taxing on females Weakened Seasonality in Horses, Goats, and Sheep Birth of young at most optimal time of the year (seasonal) Seasonality also affects behavior in male Short birth season reduces predation on the offspring of one female Testosterone concentrations in males reveal seasonal fluctuations causes display of male behavior patterns – aggressive behavior Timing of Copulation for Highest Conception Probability Exception is the domestic dogs Female’s ova will be fertilized by the strongest male available > Female goes through two breeding periods/year > Male must be sexually active all year not true in wild types 33 34 Polygamous vs. Monogamous Mating Less than 3% of all mammalian species are monogamous The domestic dog has monogamous wild ancestors Precopulatory behaviour Wild species that were domesticated are polygamous Components Advantage one male services many females of Sexual Copulatory Behavior Artificial selection is on sire side Exception is domestic dog behaviour Male preference in dogs (monogamous tendencies of Post Copulatory Behavior ancestors) 35 36  Components of Sexual Behaviour Male Precopulatory Behaviour A. Precopulatory behaviour I. Chemical Communication (Olfaction & Courtship (motivational aspects of sexual function, results from factors that attract males and females to each other (olfactory, gustatory) visual, auditory channels) males in pursuit of females (Licking and sniffing of the female II. Tactile communication genitalia, mounting - females in pursuit of males (Seeks out males , demonstrating III.Auditory communication impending estrous) - special notation (proceptive, receptive behavior) - precopulatory stimulation of males (can increase sperm count in ejaculate, enhance fertility, Can have an impact of reproductive performance 37 38 I. Chemical Communication (Olfaction & Gustatory) Through sniffing and licking to the female genitals, urine or bedding to detect chemical substances Response of the male ü Chin resting behavior ü Flehmen phenomenon ü Camel rises his limbs on his neck Response of female ü standing behavior 39 40 41 42  Receptive Behaviour in Poultry II. Tactile Communication Consummatory phase, in which the Females display a receptive posture to mounting by the male female assumes a mating stance allowing the male’s mounting, intromission and intra-vaginal Neck grip of the male cat activates the receptive posture of the female ejaculation. Massage of reproductive tract of bull is helpful in stimulating bull to Poultry (hens) ejaculate when semen is collected via artificial vagina do not have estrous cycle, but their reproductive behaviour is set in motion Bull attempting to mount by the same reproductive hormones. Rubbing the flank and genitalia of mares by man or stallion Hen’s sexual receptivity is exhibited when hens approach males, do not move and assume a posture (mating Jealously – presence of cow with another bull stance). Watching another male mate stimulates sexual performance 43 44 III. Auditory Communication Can compensate for loss of olfactory stimuli Vocalization increases during courtship Stallion - Snort Ram - baaing 45 46 Female Precopulatory Behaviour A-Chemical Clues or Olfactory Communication The Female in estrus must provide the clues (Stimuli) for By pheromones (chemical substance ) mating to the male as: She-camel (poll gland) A-Chemical or Olfactory communication Queen (special gland, anal gland) B- Visual communication male rat detect estrus female at some distance by odour. C- Auditory communication male dogs are attracted to the urine of D- Tactile communication estrus bitch. E- Motor clues( Posture & movement) Presence of pheromones in urine of cattle 47 48  C- Auditory Communication B- Visual clues or communication Through vocalization during estrus as: a. Cow : bellow Chimpanzees b. Ewe : bleat Swelling and reddening of c. Mare : snort the skin at the perennial d. Cat: emits a heat cry region called sexual skin D- Tactile Communication Through a. licking (cow, sheep) b. mutual grooming (monkey) and rubbing (cats) 49 50 E – Motor clues( Posture & Movement) Components of Sexual Behaviour B. Copulatory Behaviour (Consummatory Responses) Pro-estrous females show : A behavioral pattern that occurs in response to a stimuli increased motor activities restless Culminate or terminate a sequence of sexual interactions and continuous moving In males, ejaculation is the primary consummatory response Difficult to identify consummatory response in female Standing heat in cow Exception is cats and dogs Female lion (lioness) : may crawl up ü Extreme excitement at intromission by male (cats) to and squeeze underneath the lion ü Twisting and tuning by female dog at intromission if he is not responsive to her Greater precopulatory behavioral variation than consummatory behavioral variation advances and odor Some males go through much longer courtship than other males Little variation exist in ejaculatory reactions among males 51 52 Components of Sexual Behaviour B. Male Copulatory Behaviour a. Erection and protrusion of penis b. Mounting and fixation Erection and protrusion of c. Intromission penis d. Ejaculation and ejaculatory thrust e. Dismounting 53 54  Mounting & Fixation Mounting & Fixation 55 56 Ejaculation & Intromission ejaculatory thrust Dismounting - penis soon retracted into the prepuce 57 58 Components of Sexual Behaviour Components of Sexual Behaviour B. Female Copulatory Behaviour B. Female Copulatory Behaviour a. Estrus pattern a. Estrus pattern Time of A.I. b. Estrus detection 7-18 hours after onset of estrus c. Receptivity and mating by the male 6-28 hours after onset of heat 12-18 hours after onset of estrus Second day and every other day in estrus 16-24 hour after onset of estrus and again 8-24 hrs later 59 60  Components of Sexual Behaviour Components of Sexual Behaviour B. Female Copulatory Behaviour B. Female Copulatory Behaviour b. Estrus detection Perform heat detection when the animals are relaxing during normal activities; avoid times of increased excitement or stressful situations, such b. Estrus detection as feeding or milking. Cattle: The best times to observe for signs of estrus are during the coolest times of the day, early in the morning, before feeding and milking, early afternoon, Primary sign of estrus Secondary signs of and late evening, after the animals are finished eating and before or after estrus milking. “Standing to be mounted” Unfavorable weather, sudden weather changes, stresses, and nutritional Secondary signs of estrus problems can affect how estrus is displayed. Primary signs are the most reliable and secondary signs are less reliable Attempting to mount other cows because they vary in length and intensity and may be confused with the Mucous discharge symptoms that are the indication of a minor health problem, such Swelling & reddening of the vulva increased urination, isolation, and decreased feed intake, often observed with sick or diseased animals. Restlessness, bellowing, chin resting, trailing other cows 61 62 Components of Sexual Behaviour Components of Sexual Behaviour B. Female Copulatory Behaviour B. Female Copulatory Behaviour b. Estrus detection b. Estrus detection Goats: Sheep: Seek out male Walk fence lines Increased vocalization Rapid tail movement; raised tail Decrease in milk production and appetite Reddened swollen vulva Teaser ram often needed to detect heat in ewes. 63 64 Components of Sexual Behaviour Components of Sexual Behaviour B. Female Copulatory Behaviour B. Female Copulatory Behaviour b. Estrus detection b. Estrus detection Horses: Swine: Frequent urination Swelling & Reddening of vulva Squatting posture Mucous Discharge Winking of labia Riding Raising of tail Seeking the boar Receptive towards stallion Standing reflex Discharge from vagina Back-pressure test 65 66  Components of Sexual Behaviour Components of Sexual Behaviour B. Female Copulatory Behaviour C. Male Post – copulatory Behaviour c. Receptivity & mating by the male Refractory Period When the male approach the female: standing heat as in farm Refractoriness: animals Post-coital displays are scarce in domestic animals The female cat, rabbit, and swine take the lordosis (Crouched) Most animals show sexual inactivity immediately after copulation Ram and bulk in exception usually lick the penis after ejaculation. the female stimulated by the male Cats smell the site of copulation. arched back, and downward at the center Bring the chest in contact with the ground. The duration of this period is variable and modified by environmental stimuli ( 5 min to one hour ) Bring the genital region up. This period is decreased by changing the female the tail if present is turned to one side. 67 68 Components of Sexual Behaviour Components of Sexual Behaviour C. Male Post – copulatory Behaviour C. Male Post – copulatory Behaviour Frequency of Copulation Orgasm-like reaction Varies with species, breed, ratio of male and female, climate, Occur in cow just after copulation and period of sexual rest. The cow arches her back and elevate the tail and keep this High No. of ejaculation is in bull and Rams than Stallion and b urinating posture for several minutes Boar. Bulls copulate 80 times/ 24 hours The bull, Stallion reach exhaustion after smaller No. of ejaculation 69 70 Components of Sexual Behaviour “NOSING” may cause: C. Female Post – copulatory Behaviour 1. LH release 2. Oxytocin release - increase sperm transport and the Post-mating behaviour in Queen number of sperm reaching the site of fertilization As the male withdraws his penis after ejaculation and due to (ampulla of the oviduct for spines, it cause pain and the cat make a dramatic cry. most farm mammals). 3. In male, may improve the quality of ejaculate, similar The cat turn aggressively on the male. to the effect of false mounting. In case of familiar male, she again rolls on the floor and licks her vulva. 71 72  Sheep: (pheromones from ram) 1. Stimulate reproductive behaviour 2. Ewe come to estrus 2 weeks before onset of Male Presence and breeding season Sexual Maturity 3. High incidence of estrus synchronization In addition to season and other Pigs: the strongest and most significant in pigs that influence onset environmental effects, the presence of of puberty in developing gilts is physical mature boars. mature males significantly accelerate sexual maturity in many if not all female Causes: species. - 30-40 days earlier to reach puberty- induce gilts into estrus and Birds: pain bonding (canaries, ring dove etc.) strengthen the signs of estrus. 1. The presence of adult male partner can - Older (at least 10 months old) and experienced boar with high stimulate estrogen to trigger libido, frequent grunting and strong smell which stimulate strong development of ovarian follicles and heat response from gilts. ovulation. 2. 2.Even visual and auditory stimuli- induce - Timely and adequate boar exposure will to lay eggs. assure appropriate age and weight on the 2nd & 3rd cycle. 73 74 Some animals displaying homosexual behavior 1. Homosexuality Cat (domestic) 2. Hypo- & hyper sexuality Cattle (domestic) Abnormal 3. Inability to copulate Chimpanzee Sexual a.Impotence to mount Dog Behavior in b.intromission failure Giraffe Males 4. Buller-steer syndrome Goat Horse (domestic) 5. Auto-erotic behaviour Human 6. False ejaculation Lion 7. Outside ejaculation Chicken Mallard Ostrich 75 76 Buller-Steer Syndrome False Mounting & Unsuccessful Mounting This a common health and economic problem in feedlot operations The typical buller-steer sexually attracts his penmates who take turns following and mounting the abnormal animal. It does not seem to be associated with rank, and may be due to boredom. When detected, bullers are segregated and treated for injury or illness. Approximately 2% of steers in a feedlot situation are buller steers 77 78  Abnormal Sexual Behavior in Males 1. Silent heat Atypical sexual behaviour, such as homosexuality, 2. Nymphomania Abnormal 3. Post-partum Anestrus hypersexuality, masturbatory behaviour, may be caused by genetic flaws, endocrine imbalances, management Sexual 4. Mounting humans problems, and in many cases may be reversed. Behavior in 5. Delayed puberty Masturbation in males is common, especially in bulls Females 6. Post-coital dramatic behaviour in on a high protein diet. Humans may modify behaviour by processes such as a. Dog castration, spaying and endocrine implants to increase b. cats production and ease of handling. 79 80 Silent Heat or Quiet Nymphomania Ovulation Such cows behave like bulls, pawing and mounting but refuse Ovulation not accompanies by to stand for mounting by other cows. It could be an inherited clear signs of sexual receptivity, common in young trait. and virgin females It is more common in high-producing dairy cows than in cows To overcome this problem, use of beef breeds. of testosterone treated cows or vasectomized bulls – Nymphomania is usually associated with follicular cysts identify those who mounted by them. 81 82 “ Chapter VI 83 84  What are pheromones? ❧ The term ‘‘pheromone’’ is based on the Greek words Pherein – to transfer Hormōn – to excite ❧ Pheromones are chemical substances, which are excreted from the body, and of which one individual can smell the scent of the second individual of the same species, which cause a specific reaction. ❧ This reaction may be a manifestation of a specific behavior or the initiation of a physiological process, usually by changing the level of activity of the hormones 85 86 What are pheromones? What are pheromones? ❧ The composition of the pheromones may be saturated carbonic urine, estrogen acid, steroids, aldehydes, ketones, alcohols or other mucus, compounds. For example: Androstenol and androstenone in feces, sebum, boar's saliva as sexual attractants. sweat, saliva, ❧ Pheromones are either volatile or soluble substances and due to milk, the sensitive cell (receptor) by inhalation or physical contact. exhaled air ❧ They can be attached to other molecules or carrier, for example, or be transformed by bacteria before they become pheromones. 87 88 What are pheromones? Receptor Organs ❧ In mammals, several types of ❧ Pheromones are pheromone that regulate detected subliminally behavior (releaser through the Vomeronasal Organ pheromones) (VMO) ❧ Pheromones that regulate ❧ The VMO system consists of physiology (primer relatively small receptors in the pheromones). nose which detects pheromones and relay it to the hypothalamus portion of the brain 89 90  Female Pheromones Female Pheromones ❧ Thought to be produced in the urine and vaginal secretion ❧ The above behavior may elicit urination from the female ❧ The odor is present only at estrus and proestrus of the under investigation and the male performs a behavior known cycling females as “flehmen” (raised head with open mouth and curled upper lip) ❧ The components of the male sexual activity, the “anogenital investigation” includes the following: 1. sniffing 2. licking 3. muzzling the anogenital region 91 92 Female Pheromones Female Pheromones In Cows In Swine ❧ Urine from estrus cows also cause positive effect (sexual ❧ Urine and cervico-vaginal mucus from estrus sows/gilts have arousal) on bulls been helpful in training boars to mount dummy sow for ❧ Vasectomized bull markers have been used to detect estrus semen collection cows in the range 93 94 Male Pheromones and their effect on sexual Male Pheromones and their effect on sexual behavior of females behavior of females ❧ Males also emit sex attractants which estrus females can In cattle: detect and respond ❧ Spraying bull urine on the nose and mouth of heifers has In swine: influenced their attainment of puberty ❧ Estrus sow spend more time with intact males than with In goat: barrows ❧ The role of pheromones in influencing the sexual behavior of ❧ Removal of olfactory bulbs resulted in estrus sow unable to does discriminate between male and female on the basis of sight ❧ Physical contact with buck greatly influenced the ovulation and hearing alone of does as compared to odor alone 95 96  CHAPTER 6 97 98 Parturition And why is that? - The act of giving birth to a young - Hormonal changes occur in the female throughout Energy Expenditure: Pregnancy and gestation are taxing on pregnancy until just before parturition an animal's body. Having multiple offspring at once can be particularly energy-draining. A shorter gestation period - Termination of pregnancy is considered to be largely allows the mother to conserve energy and resources, which controlled by an increase in fetal glucocorticoids can then be used to care for the newborns after birth. originating from the adrenal cortex Size of the Offspring: Animals that give birth to multiple - Among mammals, gestation is of shorter duration for offspring tend to have smaller babies compared to animals those giving multiple births that give birth to a single offspring. Smaller babies require less time to develop in the womb, hence a shorter gestation period. 99 100 Role of Progesterone & Estrogen: And why is that? Gestation & Parturition Role of Progesterone at early age of pregnancy: Survival Strategy: Many animals that have multiple offspring follow a 1. Increasing blood flow to the womb by stimulating the reproductive strategy known as "r-selection." This strategy emphasizes high growth rate and reproduction of a large number of growth of existing blood vessels offspring quickly, with less parental care per offspring. The idea is that 2. Stimulating glands in the lining of the womb (the even if many offspring do not survive, enough will reach maturity to continue the species. This contrasts with "K-selection" strategy where endometrium) to produce nutrients that sustain the animals produce fewer offspring but invest more resources and care early embryo into ensuring their survival. 3. Stimulating the endometrium to grow and become Development at Birth: Animals producing many offspring per litter thickened, producing the decidua, a unique organ that often give birth to offspring that are less mature, in a sense that they supports the attachment of the placenta and allowing need more time to grow and develop after birth before they can implantation of the embryo become independent. In contrast, animals giving birth to one offspring at a time often give birth to relatively mature and developed offspring. 4. Helping to establish the placenta 101 102  Role of Progesterone & Estrogen: Role of Progesterone & Estrogen: Gestation & Parturition Gestation & Parturition Role of Progesterone at mid-late age of pregnancy: Role of Estrogen at pregnancy: 1. Being important for correct fetal development 1. Maintaining, controlling and stimulating the production of other pregnancy hormones 2. Preventing the muscles of the womb contracting 2. Needed for correct development of many fetal organs until the onset of labor including the lungs, liver and kidneys 3. Preventing lactation until after pregnancy 3. Stimulating the growth and correct function of the placenta 4. Strengthening the muscles of the pelvic wall in preparation for labor 4. Promoting growth of maternal breast tissue (along with progesterone) and preparing the mother for lactation (breastfeeding) 103 104 Role of Progesterone & Estrogen: Gestation & Parturition Parturition Hormones at parturition: Parturient behavior is characterized by a series of 1. Oxytocin* - causing regular contractions of the connected episodes that collectively make up the womb and abdominal muscles. process of ‘before, during and after’ birth. 2. Prolactin* Many free-living species seek out remote or 3. Prostaglandin concealed sites for giving birth. 4. Relaxin Many animals separate themselves from the main group and select a site for the birth. 5. Beta-endorphins 6. Adrenaline & Noradrenaline *Also occurs after parturition. 105 106 Parturition Phases of Parturition 1. Many free range choose inaccessible areas where the birth may occur unhindered. Normally with single birth species, there are three 2. Domesticated ruminants often appear to withdraw from the grazing phases: group when birth is only an hour or two away. 3. Pre-parturient sow 3 days before onset of labor is spent sleeping & 1. Pre-parturient period feeding, an increasing amount of nest building behavior (bedding and chopping). 2. Birth 4. In the immediate pre-partum phase, definite behavior patterns emerge. 3. Post-parturient period Increasing restless and frequently alters her position and disposition. Recognition of this behavior-allows the time of birth to be predicted accurately. But only two phases for multiple births like pigs. Allows proper management of parturient animal and neonates. 107 108  Parturition Synchrony and Timing of Births As parturition (extends from late gestation to the beginning Seasonal breeding is the common mode of of the first labor) approaches: reproduction in natural environments - The female becomes nervous and restless, loss of appetite and the mammary glands may becomes further distended and milk may start coming out of the teats Males joining the herd will effect the synchronization of estrus resulting in more births - Under natural or even extensive production system, within a closer period of time expectant sows will build nests from whatever materials available - Some sows maybe too nervous during farrowing Under commercial intensive production system, the especially the first timer gilts animals kept are polyestrus in breeding behavior 109 110 Time of Day and Birth Postpartum Behavior Why do births mostly occur at night? Expulsion of placenta: - Due to disturbances and excitement which may be - The placenta maybe eaten by the dams to reduce experienced during the day. The aroused or the likelihood of predators being attracted to the disturbed animal may secrete adrenaline. site of birth by the odor of decomposing placenta Adrenaline could block the action of oxytocin which induces uterine contraction to expel the fetus - 86% of horses give birth on dark hours, 66% of barned cattle around midnight, 88% of cattle on pasture by late or early morning and pigs during early hours of darkness 111 112 Postpartum Behavior Suckling and Weaning - The intense licking of neonates by the dams in - The time interval following birth to first suckling of some species has behavioral and physiological teat varies among farm mammals, for piglets it reasons: could be 20 to 30 min, for beef calves and foals 1. Behavioral – establishing attachment 1.25 to 2 hours and for dairy calves from 3 to 4 and distinction from other neonates hours after birth 2. Physiological - Weaning could be a source of considerable stress - initiate eliminative behavior to offspring - establish vigorous breathing - Early weaning may have prolonged effects if poorly - reduces chances of chilling managed: 113 114  Suckling and Weaning Suckling and Weaning - lambs and calves: suckling of scrotum, navel and Calves & other neonates: ears of others - piglets: rubbing of bellies of pen mates interference getting colostrum directly from dam have less during feeding mortality than when given through bucket/pail. - A few minutes before removal from Colostrum-the first secretion from the mammary mother, the young may exhibit the following behaviors: glans after giving birth, rich in antibodies. - frequent urination and defecation Always allow calves 12 hours with dams after birth - restless (extremely active) before removing them to insure they are able to - gives a distinctive pattern of loud vocalization suck colostrum 115 116 Suckling and Weaning Piglets: -Vigorous nosing of the udder will stimulate let- down of milk Lambs and sheep: -Lambs maintain very close contact with dam for extended period – delayed weaning -Ewes with twin lambs will resist suckling by single member of the pair -both twins must be suckling 117