Reproductive Physiology and Artificial Insemination PDF

Reproductive Physiology and Artificial Insemination (AI) (AnSc 321) Sep, 2024 Bale-Robe, Ethiopia  1. What is Reproduction? The process by which organisms produce more of their own kind offspring are re...

Reproductive Physiology and Artificial Insemination (AI) (AnSc 321) Sep, 2024 Bale-Robe, Ethiopia  1. What is Reproduction? The process by which organisms produce more of their own kind offspring are reproduced. Offspring are produced by male and female parents. It involves heterosexual mating, conception, pregnancy, parturition and lactation. Reproduction involves close coordination of various physiological events to be successful. Types of reproduction  Two types of reproduction:- Sexual reproduction and asexual reproduction.  Sexual reproduction (sperm + egg)  Asexual reproduction no fusion of gametes  Sexual reproduction (male gamete+ female gamete= offspring) Cells of the offspring have 2 sets of chromosomes (one from each parent) Sexual reproduction involves two stages:  Meiosis- special cell division  Fertilization- fusion of 2 gametes Types of fertilization External - fish Internal (all mammals and birds) Incubations  External incubation - birds  Internal incubation – mammals  Asexual reproduction Perpetuation without sex (parthenogenesis) Only one parent is involved (no males) Offspring are genetically identical to their parents Faster population growth Types of asexual reproduction  Mitosis  Binary fission  Budding  Sporulation  Regeneration  Mitosis (Somatic cell division)  Exact duplication of the nucleus of a cell so as to form two identical nuclei during cell division. Binary Fission  Occurs in one celled organisms like ameba, paramecium  Nucleus divides via mitosis and the cytoplasm divides, forming 2 new daughter cells of equal size Budding Occurs in hydra and yeast The division of cytoplasm is unequal, one daughter cells is larger than other. Daughter cells can separate or remain attached Sporulation Occurs in molds, etc. Spores produced in large numbers by mitosis. Spores are surrounded by a tough coat to help them survive harsh environmental conditions. Regeneration The replacement or re-growth of lost or damaged body parts Parthenogenesis: is the development of an unfertilized egg into a new individual that is a clone of the parents. Animals that are parthenogenetic includes bees, wasps, ants and some species of birds and lizards. Role of male and female in reproduction Role of males Produce mature spermatozoa  Store spermatozoa until needed  Discharge spermatozoa in to female tract and fertilize the egg Role of females  Provide ova(eggs)  Provide proper environment for fertilization  Nurture the embryo/fetus(gestation)  Deliver immature individual  Provide for proper behavior patterns  Attracting males and mating  Maternal functions 2. Male reproductive tracts and physiology The male reproductive organ can be viewed as:  Primary sex organs (testes and scrotal sac suspended by spermatic cord) Secondary sex organs (duct tissues, which transport sperm from the testes to the externa and include the efferent ducts within the tests, epididymes, ductus deferens (vas deferens), the urethra and penis). Accessory sex organs (prostate gland, seminal vesicles and bulbo-urethral (cowper’s) glands). But, all the sex organs work together to form, mature & transport spermatozoa Primary organs of reproduction of male animal Testes (plural) - testis (singular)  Sperm producing organ Held in the scrotum Testicle include testes and scrotum Purpose of suspension from the body (Scrotum)  As heat regulating mechanism (for normal sperm formation)  At 4 to/or 5 °C below body temperature is essential for spermatogenesis (growth and maturation of the sperm) Functions of testes Testes has 2 vital functions:- a. Produce testosterone Leydig (Interstitial) cells or gonads b. Site of spermatogenesis (sperm production) - within seminiferous tubules  Regulation or coordination of 3 structures: 1)External cremaster muscle within the spermatic cord  Consists of Cremaster muscle, Ductus deferens, Testicular artery, Pampiniform plexus 2)Temperature-sensitive layer of muscle  The scrotum is lined internally by muscle (Tunica dartos) 3)Counter-current temperature exchange  Regulated by pampiniform plexus (a complex network of veins, around the spermatic artery, in the base of the card). Cremaster muscle within the spermatic cord Muscle from internal abdominal oblique Can only sustain short periods of contractions (does not work well to pull up testis) Primarily a pumping action on the pampiniform  The interior of the testis Divided into compartments (lobules)  by fibrous membranes (septa) Each lobule consists of:-  Semniferous tubules (up to four)  They are embedded in tissue consists of:- Blood vessels, Nerves and Leydig cells The testis contains: Long, tiny, coiled tubes known as seminiferous tubules  Seminiferous Tubules In the seminiferous tubules sperm formed & begin to mature Seminiferous tubules are surrounded by Leydig cells  Highly specialized cells  Produce testosterone Semniferous cells are of 2 types Spermatogenic cells (Spermatogonia) divide and differentiate to from spermatozoa Sertoli cells (provides a microenvironment for normal spermiogensis.  Functions of spermatogenic and sertoli cells Spermatogenic cells (spermatogonia) Give rise to spermatozoa Sertoli cells  Supply nutrients to spermatogonia The secondary sex organs:-  Epididymis  Vas deferens  Penis Epididymis Flat and convoluted structure Attached to one side of the testicle  General functions of epididymis Mature sperm: release of protoplasmic droplet from sperm Store sperm: mainly in the tail (up to 60 days motile and fertile) (sperm collecting ducts) Transit sperm : 10-12 Days Absorb sperm: in prolonged sexual rest Secrets glyceryl-phosphorylcholine which is metabolized by sperm in female genitalia for gaining more energy during capacitation Parts of Epididymis Epididymis is divided into 3 regions Body of Epididymis  Caput Epididymis (head)  Sperm maintain mobility  Corpus Epididymis (body)  Sperm maintain mobility  Cauda Epididymis (tail)  Principal storage of sperm  Contains ≈ 70% of total epididymal sperm  Vas deferens (Ducts deferens)  Cord like structure and it joins ducts of seminal vesicles  Emerges from tail of epididymis to pelvic urethra  Passes as part of spermatic cord  Its Ampulla secrete fructose and citric acid (branched tubular glands, which in the stallion, are highly developed and contribute ergothionine to the ejaculate). Function of Vas (ducts) deferens: transport sperm from epididymis to the urethra at the time of ejaculation  May contain large number of sperm equal ejaculate  Nutritive to stored sperm  Sperm stayed alive, motile & fertile for 3 days then loose its fertilizing capacity  May absorb dead sperm Penis The organ of insemination  Consists of 3 parts  Root  Body Glans penis Mainly composed of erectile tissue Forms s-shaped curve (sigmoid flexure) behind scrotum  Urethra Begins at the opening of bladder and is continuous with the penis Posterior portion of the urethra is S-shaped (Sigmoid flexure) The Sigmoid Flexure An S-shaped curve behind scrotum It extends the penis outside of the body and into the vaginal cavity of the female so that the semen can be deposited. Strong retractor muscles hold the penis in the S shaped configuration Retractor muscle retracts the penis into the protective sheath Straightened during erection If these muscles are too weak portion of the penis protrude at all times If Sigmoid flexure doesn’t work the male is sterile  Prepuce Tubular integument that covers the free portion of penis (30-40 cm long) Tubular glands secrete smegma that modulate the condition of prepuce Function is to protect the penis Has an orifice with long tough hair and supported by protractor muscles for closure Accessory glands of male animal (accessory sex organs) Prostate gland (1) Seminal vesicles (2) Bulbo urethral (Cowper’s) gland (2) ↓ Secretions from the three glands: ↓ Make up most of the liquid portion of semen (add volume) ↓ Provide medium for the transport of sperm from testes to vagina ↓ Provides nutrients for the sperm ↓ Clean and flushes out urinary tract  The prostate gland The only gland common to all mammals Located at the neck of the urinary bladder Relatively small in the bull than other species Functions of prostate gland  Doesn’t produce very large volume secretion  Secrete large amount of minerals that regulate buffering system of seminal plasma  Secrete amino acids for sperm nutrition  It is alkaline in reaction to neutralize the acidic sperm coming from the Cauda epididymis  Participate as a vehicle media for sperm with the seminal  Seminal vesicles Lie on either side of the neck of the bladder Each has excretory duct Functions of seminal vesicles  Secrete main volume of seminal plasma (>50%) which act as a vehicle to sperm activity  Secrete Fructose for energy to sperm  Secrete citric acid as buffer to sperm  Secrete K and iron to control equilibrium of osmotic pressure  Secrete flavin which give yellow coloration to normal ejaculate in few bulls  Bulbo-Urethral (Cowper's) glands Small, firm glands Located on either side of the urethra, behind the prostate. Has secretory duct to pelvic urethra Function of bulbo-urethral glands (Cowper's glands)  Flush, clean and neutralize the urethra of any urine residue (may be harmful to spermatozoa)  The clear secretion that often drips from the penis during sexual excitement prior to service is largely produced by these glands Accessory gland fluids contain Sodium chloride Potassium chloride Nitrogen Citric acid Fructose Several vitamins  Purposes of accessory gland fluids Add volume to the ejaculates Enhance sperm survival Enhance sperm movement Provision of nutrients for sperm Provision of electrolytes for sperm Lubrication for mating process Neutralization of urinary acid residues in urethra 3. The female reproductive tracts and their physiologies The Female Genitalia Consist of: Vulva Vestibule Vagina Cervix Uterus Fallopian tubes (oviducts) Ovaries Supporting structures  The overall functions of female reproductive tract Transport sperm Produce oocytes Facilitate fertilization Provide environment for embryo & fetus Give birth to fetus Recycle to become pregnant again Provide nutrients to young Female bovine reproductive tract 1. Vulva (lips)  External vertical opening of genital tract just below anus Allow the entry of bull’s penis (AI gun) at service Allow the expulsion of calf at birth Exit point of urine from the body 2. Vestibule Part of the reproductive tract shared with the urinary system The common duct for urine & reproduction Glands of Bartholin( lubricating gland) contribute to lubrication during estrus 3. Vagina  Located between cervix & vulva  Copulatory organ  Responsible for secretion of mucus  Admits male organ during copulation  Transport & temporarily store sperm  Serves as a birth canal  Line of defense against invasion by bacteria Line of defense against invasion by bacteria  Epithelium of the vagina secretes fluids which combine with cervical fluids to inhibit growth of undesirable bacteria  Protection from infections may not be sufficient when there is unsanitary housing conditions, or dirty AI equipment is used The vagina wall  Tough and highly elastic  The lining (epithelium) changes with the stage of the oestrous cycle 4. Cervix The organs near to the vagina  Produce mucus  Active around the time of estrus Cervix uteri Neck of the womb Lies between the vagina and uterus  Function of the cervix Acts as a reservoir for semen Selector of viable sperm  Prevents transport of nonviable and defective sperm (trap non-viable sperm, sperm filter)  Prevent large number of sperm from reaching oviduct in cow and ewe Dilatation to permit parturition & expulsion of fetal membrane Cervical canal (lumen): tightly closed and dilate at parturition and at estrus (dilate slightly) Secretions of the cervix is normally thick But, thin at the time of estrus ( to facilitate transfer of sperm to the uterus) The thick plug Act as a physical barrier Blocks access to the pregnant uterus  from any foreign material  from bacteria Note: during AI semen is deposited in the anterior cervix. 5. The Uterus Hollow muscular organ Consists of ‘body’ and two ‘horns’ Suspended in the pelvic cavity by the broad uterine ligaments on either side Body of uterus is adjacent to cervix Layers in wall of uterus  Has three layers Outer – Perimetrium Outer serous layer continuous with peritoneum. It blocks adhesions or linkages Middle – Myometrium  Inner circular layer of smooth muscle  Outer longitudinal layer, peristaltic contractions Inner – Endometrium Provides point of placental attachment, glands provide secretions for embryo development (Estrogen and Progesterone) Functions of uterus Transport of sperm - when female is in heat Estrogen stimulates myometrial contractions so that sperm move to site of fertilization Viable sperm (motile) are important so that they are not absorbed Muscle contractions Towards oviduct during estrus (heat) but Following ovulation towards cervix until progesterone increases from  Functions of uterus … Absorption and phagocytosis occurs by uterine epithelium Leukocytes fight infection Partially prepares sperm for fertilization Estrogen stimulates uterine secretions which capacitate sperm(in endometrium Provides environment for embryo till birth Secrete fluid (uterine milk) which provide nutrients to developing embryo before & after its attachment. Secretion is stimulated by estrogen & progesterone Expels fetus at birth Recovers from pregnancy & makes corpus luteum regress Components of the uterus Horn & Body 1) Horns Two cornua  Pig - Bicornuate  Cow – Bipartite 2) Body Fusion between horns Allows trans uterine migration in ewe, mare, pig Site of semen deposition in mare, sow 6. The oviduct (fallopian tubes) Lie between ovary & tip of uterine horn End of the oviduct is funnel shaped - called infundibulum  Consists of 3 segments ( Isthmus , Ampulla , Infundibulum )  Functions of the Fallopian Tubes 1) Oocyte retrieval after ovulation 2) Site of fertilization 3) Oocyte/ovum transport to uterus Egg travels from ovary to uterine horn in 3 - 4 days Oocyte retrieval after ovulation  Removes oocyte from surface of ovary Site of fertilization Transport oocyte and sperm to site of fertilization Reduce sperm number to prevent polyspermy Provide proper environment for Oocyte, sperm & fertilization Oocyte/ovum transport to uterus Transport & facilitate development of early embryo  The Isthmus (narrow proximal portion) Extends from the tip of the uterine horn for about half the length of the oviduct The Ampulla A slightly wider section opening into the peritoneal cavity via the funnel like third portion ( infundibulum) The Infundibulum The funnel shaped portion of the fallopian tube near the ovary that catches Serve to capture the ovulated egg as they shed from ovary at ovulation Pushes the ovum into the fallopian tube during ovulation Facilitate their passage down the oviduct  7. Ovaries Primary reproductive organ of female Suspended from the broad ligament Ovarian structure is not static Appearance of the surface changes:  Follicle growth, ovulation or The ovary is responsible for the: Production of the female egg or ovum  Gamete production ……..gametogenesis  Production of hormones….steroidogenesis  Estrogen and progesterone  Inhibin, relaxin, oxytocin The ovaries contain thousands of ova All ova are surrounded by a special layer of cells in the ovary The growth of these cells produces blister like structures, called follicles that are visible on the surface of the ovary As follicle enlarges, it appears as a large blister on the surface of the ovary and can be easily detected by rectal palpation  The ovary is responsible for:- Development of ovulatory follicles begins at puberty They develop continuously throughout the life of the cow & the vast majority regresses without releasing the ova Following ovulation, the walls of the follicle collapse & develop into corpus luteum (CL) or yellow body The CL reaches its maximum size 10-12 days after ovulation & is the dominant structure on the ovary If pregnancy does not result, CL regresses 3 to 4 days prior to the next ovulation The presence of embryo in uterus prevents this from happening Development of the follicle and subsequent formation of the CL are associated with the production of estrogen and progesterone  Reproductive tract in male poultry The male poultry anatomy consists of two testes (each with an epididymis and vas deferens) that lead to papillae and a rudimentary copulatory organ. Unlike other livestock species, the testes of poultry are located within the abdominal cavity along the backbone. The epididymis, which still functions in sperm storage, is relatively small in relation to the testes. The vas deferens extend from the epididymis to the cloaca are located on each side of the vertebral column. The vas deferens function in transportation of sperm and as sperm reservoirs. Cloaca – the lower end of the avian digestive  Papillae – located at the end of the vas deferens and on floor of the cloaca, the papillae emit semen into the cloaca of the female. Phallus – a rudimentary copulatory organ that becomes engorged with lymph during mating, which allows semen to be deposited onto the female’s everted cloacus; the phallus is more developed in ducks and geese. Androgen – the male sex hormone produced by the testes. Functions of androgen include:  Directing sexual activity and production of sperm,  Controlling secondary sexual characteristics of the male, and  Influencing social rank or “peck order.”  Secondary sexual characteristics include comb growth, crowing or gobbling, spur development, and male feathering.  Reproductive tract in female poultry The female reproductive system in fowl is quite different from that of the mammals. Only the left ovary and oviduct of the hen are functional, although the right is found in an underdeveloped state. The oviduct has five parts:- the infundibulum, magnum, isthmus, uterus, and the vagina. A cloaca and vent are located at the end of the oviduct. Functions of the parts Ovary – the ovaries produce the female sex cells, called eggs or ova, and sex hormones. The ova are released from follicles on the ovary. Infundibulum – the infundibulum receives the egg from the ovary. Oviduct – the oviduct, or fallopian tube, is a tube-like structure that carries the egg from ovary to the uterus. It is also the site where sperm and egg meet during fertilization. Uterus – the fertilized egg develops in the uterus before birth. Uterus – Also known as the shell gland, the uterus adds a thin white, shell, and pigment to the egg. Vagina – The egg is temporarily stored in the vaginan before it is laid. It also produces the cuticle, the exterior coating of the shell. Cloaca – The cloaca, which is the junction of the digestive and reproductive systems, receives the male’s semen. The egg passes through the cloaca during laying. Vent – The vent is the opening through which the egg passes out of the body during laying.  2. Reproductive hormones  Organic substances secreted by certain specialized cells (glands)  They are diffused to some other body part and bring about certain changes. Reproductive hormones are produced from hypothalamus, pituitary, gonads, uterus, placenta Cause Release of other hormones (releasing hormones) Stimulate gonads (gonadotropins) Sexual promotion (steroids) Pregnancy maintenance Hormones involved in reproduction can be classified as primary and secondary (metabolic) hormones 1. Primary hormones  Directly involved in various aspects of reproduction e.g. spermatogenesis, oogenesis, & ovulation 2. Secondary hormones (metabolic hormones) Are hormones that indirectly influence reproduction They are needed for normal functioning of organs which makes it possible for reproduction to occur  1. Primary hormones of reproduction They are involved in spermatogenesis, ovulation, sexual behavior, fertilization, implantation, maintenance of gestation, parturition, lactation, maternal behavior Primary hormones of female reproduction  Estrogen  Follicle stimulating hormone  Luteinizing hormone  Gonadotropin releasing hormone  Oxytocin  Progesterone  Prostaglandin  1. Estrogen Produced by the cells lining the wall of the follicle and responsible for:- Changes in behavior of cow Adjust the production of fluids by the vagina, uterus and cervix Trigger/activate the release of LH (luteinizing hormone) As a result of these synchronized events, Cow comes into estrus and can be mated Fluids of the tract provide a favorable environment for survival of the sperm and ova, and Ovulation occurs at the time when sperm will be available to cause fertilization. Sites of production of estrogen  Functions of oestrogens Stimulate follicular growth and maturation Induce females to display estrous behavior Contribute to growth & development of mammary tissue Prepare the uterus for parturition  Secretory glands enlarge & thickening of tissues  Significantly increase blood flow Increased uterine muscle tone and stimulate mucus secretion in the2. cervix and vagina Progesterone It is produced by corpus luteaum and placenta which is essential for pregnancy During pregnancy Concentration of progesterone high and inhibits secretion of GnRH Prevents ovulation of follicles during luteal phase Concentration of progesterone  Increases after ovulation then decreases near term  Altering ratio between progesterone and oestrogen Stimulates myometrial activity  Functions of progesterone Prepares uterus for reception of fertilised oocytes Stimulates growth of glands in endometrium to increase secretion of mucin & carbohydrates Nourish embryo prior to implantation Stabilizes smooth muscle cells of endometrium to ensure that they do not contract during foetal development. Prepares mammary tissues for milk production Prevents 3. Prostaglandin cow from coming into heat Secreted(PGF2α) by the uterus Causes regression of CL and decrease in progesterone levels. If cow is pregnant, embryo will block the release of PGF2α and allow CL to continue to secrete progesterone. 4. Gonadotropin releasing hormone (GnRH or LH-RH) In male and females, stimulates the anterior pituitary to secrete FSH and LH which control ovarian function Causes ovulation of the dominant follicle a. Luteinizing Hormone (LH)  Secreted from the pituitary gland  Its secretion is regulated via the secretion of GnRH i.e. travels through  a. Luteinizing hormone (LH) … LH in males  Stimulates interstitial cells of testis  Stimulates the production and secretion of testosterone from the testes via leydig cells. LH in females  Stimulates interstitial cells of ovary  Stimulates production of oestrogens & progesterone from the ovary via theca interna cells and luteal cells  LH is responsible for: Rupture of follicle wall of dominant follicle and ovulation Stimulate the CL to secrete progesterone b. Follicle stimulating Luteinisation of granulosa & thecal cells hormone (FSH) Secreted by the pituitary gland Regulated by GnRH from the hypothalamus Target tissue of FSH In males - Sertoli cells (within the testes) In female - Granulosa cells of the ovary FSH in males Stimulates maturation of sperm cells  FSH in females  Stimulates follicular development and oestradiol synthesis i.e. stimulates growth & maturation of the ovarian (Graafian) follicles  Does not cause secretion of estrogen from ovary by itself; instead, it needs the presence of LH to stimulate estrogen production  Travels through blood to the ovary after being signaled for its release by GnRH  2. Secondary hormones of reproduction Indirectly influence reproduction Regulation of reproduction The main elements of regulation are: 1) Nervous system: fundamental responsibility in translating or transducing external stimuli into neural signals 2) Endocrine system:- pathways are neural reflex and neuroendocrine reflex Hormone Physiologic organic/chemical substance synthesized and secreted by ductless endocrine gland Passes into the circulatory system for transport and bring about certain changes Functions of hormones Inhibit, stimulate, or regulate the functional activity of the target organ or tissue. Regulation of hormone secretion is by nervous system Regulation of gonadal activity is by:  Endocrine feedback mechanism  1) Endocrine feed back mechanism Feedback control occurs at hypothalamus & pituitary gland level Depending on their concentration in the blood, steroid hormones may exert stimulatory (positive) or inhibitory (negative) feedback Gonad Inhibitory (negative feedback) Stimulatory (positive fed back) Hypothalamic hormones Inhibitory (negative)feedback This system involves reciprocal interrelationships between two or more glands and target organs e.g., As stimulation of the ovary increases estrogen secretion, FSH levels declines Stimulatory (positive) feedback In this system, an increasing level of hormone(s) causes subsequent increase of another hormone e.g., Increasing levels of estrogen during the pre ovulatory phase trigger an abrupt release of pituitary LH These two events are precisely synchronized, because LH surge is  Hypothalamic Pituitary &hormones Steroid hormones regulate the synthesis, storage, & release of hypothalamic hormones through two feedback mechanisms: 1. Long feedback mechanism 2. Short feedback mechanism 1. Long feedback system Involves interaction among the gonad, pituitary, and hypothalamus 2. Short feedback system Pituitary gonadotrophin influences secretory activities of releasing hormones without mediation of the gonads  2) Neuroendocrine reflex The nervous system may release hormones through neural pathways, e.g., Oxytocin in milk let down, LH release following copulation 3) Immuno endocrine control  Endocrine and immune systems interact extensively to regulate each other.  Several endocrine organs are involved in some aspects of regulatory process:  Hypothalamus, pituitary, gonads, adrenals, pineal, thyroid, thymus.  Many of these organs are themselves affected by immune function 5. Reproductive behavior in farm animals Mating behavior is very strong drive & can take precedence/priority over other activities. Purpose  Promote copulation  Assure sperm and Oocyte meet Goal - to achieve pregnancy & parturition  From mating point of view Males competing for access to females Females being selective in their choice of mates Cattle As ovulation approaches, cow behaves in agitated manner to attract bulls Cow to cow mounting is common in dairy herds without bull When For sexual bull isstimulation willvision of bull present there not be appears more important than cow to cow smell mounting: The bull will guard the cow from approaches by all other cattle The bull will chase off other bulls, prevent her from rejoining the herd Cow remains behind with him as the herd moves on. The bull position Stands in the inverse polar position Parallel and close to the cow His head by her rump When cow becomes receptive (stands still) bull serve the cow about 5 times  Bull detects the estrous cow by:  Licking (smelling) around genital  Curling upper lip in characteristic manner “Flehmen” behavior Sheep and goats Similar with bull Courtship display is comparatively simple In the temperate zone They are seasonally polyestrous, breeding season is in Autumn Libido of both sexes is low outside breeding season, males are aggressive during breeding season Pigs Come into heat at any time of the year Every 21 days interval Each heat period lasts 3 days Maximal receptivity period is about 12 hours  Factors affecting expression of estrous behavior Housing, temperature, day variation, arrangement where cattle are crowded, cow density, feet and leg problems, number of herd mates in proestrus (estrus) and nutritional factors Stages of reproductive behavior The stages of reproductive behavior are: Pre-copulatory stage Search for sexual partner (sexual arousal), Courtship (sexual display) Erection Copulatory stage Mounting, Intromission Ejaculation Post copulatory stage  Dismounting  Memory  Search for sexual partner (sexual arousal/provocation)  In female limited to estrus increased physical activity  In male it can occur at any time involves all of the senses Sight, smell, hearing, tactile/ tangible  Sexual arousal Female: lordosis, presents hindquarters to male Male: erection, penile protrusion Courtship/ sexual display: It is species specific events  Types of courtship 1. Male courtship Sniffing (suggesting an important chemical communication through olfaction) Licking, Flehmen reaction Nuzzling of rump & back ( in ruminants) Biting neck (in stallion) Noses flanks Grind teeth Foams at mouth (boar) Increased vocal and motor activity Increased phonation Male checks for female lordosis Female courtship Restlessness, increased vocal activity , sniffing of male genitals (sniffing other female vagina), circling, mock fighting, frequent urination, mount other females (in cows, goats, pigs) Tail wagging ( in sheep & goats) Vulva “winking” (in horses)  Erection Erection of the penis requires: Copulatory behaviour Elevated arterial blood inflow Varies among species Restricted venous outflow  Short copulators (1 - 3 Elevated intrapenile pressure seconds) Relaxation of the retractor Bull and Ram penis muscle  Intermediate (20 to 60 Copulatory stage seconds) Mounting Stallion Intromission  Sustained copulator (5 - 20 minutes) Ejaculation Refractoriness Boar Refractory period: is period of time during which copulation will not take place Refractoriness dependent on Sexual rest prior to copulation Age of male Degree of female novelty/virginity Number of previous ejaculates All males have refractory period  Estrus and estrus cycles  Puberty is the stage of sexual maturation as a desire to mate and ability to produce sperm capable of fertilizing an egg in males and;  In female production of ova by follicles, development of the reproductive tract to give the capacity to bear offspring, and a desire for mating.  Puberty is marked by the first estrus in female while estrus (heat): period of sexual receptivity Estrous cycle:  Interval from beginning of one estrus to the beginning of the next  Interval between 2 consecutive heat periods  Average length is 21 days (18-22days in heifers; 18-24 days in cows) Mono estrous (seasonal breeders): Animals that have only one estrous cycle/year Polyestrous: Animals that have several estrous cycles per year Oestrous cycle Cattle and swine No seasonality of breeding Sheep and goats In tropical countries no seasonality of breeding In temperate climate they have breeding season  Phases of oestrous cycle Oestrous cycle is divided into 4 phases: Oestrus - period of sexual receptivity Metestrus - post ovulatory period; Diestrus – when active CL is present Proestrus – period prior to oestrus Oestrous cycle is better described in terms of ovarian function i.e. based on the dominant progesterone and estrogen hormones 1. Follicular phase (prooestrus & oestrus) Period from regression of CL Ends when the new CL of the following cycle is formed or up to ovulation Lasts for about 3-6 days 2. Luteal phase (metestrus & diestrus)  Is the period of CL activity  Begins from CL formation (5-6 days after the onset of oestrus) and ends when CL regrets.  Described with presence of CL when implantation occurs   1. Proestrus  Is 1st phase of estrous cycle (immediately before estrus)  It lasts 2-3 days and it is the building-up (preparation) phase  Building-up (preparation phase) of reproductive organs for next estrus cycle Begins to secrete estrogens  Increase in estrogen & decrease in progesterone level in the blood (estrogens absorbed from follicles into blood)  This increases vascularity & cell growth of tubular genitalia to prepare for the next estrus and pregnancy (follicles size increase & 2. Estrus CL regress)  Pronounces heat signs, initiated by elevation in estrogens from mature follicles prior to ovulation  Vaginal mucosa progressively becomes hyperemic, uterine, cervical & vaginal glands secretion increased,  Cervix is relaxed and functional CL is absent  In most species, ovulation occurs within 1 or 2days after the onset of estrus behavioral.  Lasts about 15 hrs (range 12-24 hrs), more signs of estrus observed during night  Ovulation occurs 12 hrs after the end of estrus (on average)  In zebu duration of estrus is 7-9 hrs (shorter)  3. Metestrus  Comes following estrus  Signs of heat are less apparent  Cow does not allow to be mounted, vaginal mucosa becomes pale, reduction in secretion of mucosa  Mucus becomes sticky, pale yellowish or brown, estrogens decreases, progesterone increases  External genitalia return to their state as before estrus (as plasma estrogens decreased)  Some times little blood discharge from uterus (indicative that cow has been in heat 3-4 days before)  CL begins to grow, lasts for about 3-4 days  4. Diestrus The period of inactivity before proestrus of next cycle, lasts about 13 days after estrus CL is fully developed (palpable fully developed CL) The endometrium becomes thicker, Uterine glands increase in size  Uterine muscle will be relaxed Cervix becomes constricted Vaginal mucosa becomes pale If cow is pregnant, CL remains If cow is not pregnant, CL regress and new pro-oestrus begins Factors affecting length of  Breed estrous cycle:  Individuality within same breed  Season  Nutrition  Disease  Age  Management  Cow production status  Estrous cycles in cattle, sheep, goat and sow Puberty in cattle: when heifer should be about 2/3rd of her adult body size, Sexual maturity in cow: is the age when generative organs become functional  Before sexual maturity clear vaginal discharge is evident indicates Sexual maturity approaching sexualin maturity. heifers  It does not mean heifers are ready for insemination Exotic heifers reach sexual maturity at about 8-12 months of age; with 30-40% BW of adult Zebu heifers attain sexual maturity at about 18-24 months of age Physical maturity in cow is the age succeeding sexual maturity It is characterized by:  Rapid development of reproductive organs  Onset of heat, and ovulation Physical maturity in cow appears:  At about 12-18 months of age with 65-70% of BW of same breed BW is detrimental factor for sexual and physical maturity than age Hence, heifer should be bred when its BW attain 65-70% of given breed  Weight & age at which 1st heat appearance If heifers bred at early age or before physical maturity:  Their growth may be retarded  Encounter difficult parturition  Give birth to weak (un survival) offspring  Decrease production Young heifers should be used for production, when body attains expected physical appearance (body weight) Sexual & physical maturity may be influenced by:  Genetic and environmental factors  Nutrition  Climate  Breeding (cross breeding and inbreeding)  Disease condition  Presence of neuro-sexual stimulant (opposite sex)  Cow Length of estrous cycle:  Exotic breed 18 – 24 days ( 21 days) for cows 18 - 22 days for heifers  Zebu - 17 to 24 days Duration of estrus: Normal range is 12 - 24 hours. 10 hrs in zebu (Bos indicus) 11 – 15 hrs in Bos taurus in the tropics & subtropics  Ovulation occurs about 10 to 14 hours after the end of estrus Time of breeding:  Bovine spermatozoa must present for at least 6 hours in the uterus (uterine tubes) before they are capable of fertilizing an ovum. For AI application If heat appears in the morning, bred in the afternoon, If heat appears in the afternoon, bred the next morning  Ewe Puberty: 6 - 7 months of age Length of estrous cycle: 17 days; some tropical breeds have shorter cycle of 14 - 19 days Length of estrus: 30 hours (24 - 40 hrs). Ovulation: Occurs 24 -36 hours from beginning of estrus Ewe will accept ram only during estrous period Ovulation occurs near termination of estrus 2 or 3 ovulations may occur in one estrous period In temperate climate ewes are seasonal polyestrous Females ovulate & exhibit estrus almost the whole year, even though short periods of unovulation & anestrous are detected in some females. Two main hypotheses can be raised to explain the near absence of seasonality. i.e. either:  Females are insensitive to photoperiod, or  Amplitude of photoperiodic changes is too small to induce seasonality Doe Puberty: 6 - 7 months of age Length of estrous cycle: 21 days (also short cycles) Length (duration) of estrus: 24 - 36 hrs (20-35) Ovulation: occurs 21 - 36 after start of oestrus Local sheep and goat breeds are either non seasonal breeders or exhibit only a weak seasonality In Ethiopian highlands, most conception in sheep and goats occurs during (following) short rains in March through May Under normal circumstances (without drought): Tropical sheep/goats should lamb/kid at least three times in 2 years Lambing/kidding interval should not exceed 8 months (245 days) Sow Puberty: 6 - 7 months of age. Estrous cycle: 21 days (18 - 24 days) Duration of estrus: heat lasts 3 days Ovulation: occurs by the 2nd day of estrus or any time thereafter Sexual receptivity: averages 40 - 60 hrs At each period 11 - 24 ova are shed  Behavioral signs of estrus Detection of estrus is important when we use AI (when sires don’t run with females) So, identify the signs of estrus. Doe Bleating continuously, restlessness Flagging of the tail, frequent urination Mounting on other goats, seeking the buck Swollen red colored vulva Ewe Cervical mucus discharge, which causes hairs to stick together The signs are not obvious vulva is swollen and redder than usual Mucus discharge from the vagina (difficult to see in a ewe with a tail or fleece) Stands when mounted (standing heat ) All of the symptoms mentioned may not be exhibited by ewe in estrus  Cow Sow  Restlessness, bellowing Restlessness  Swelling & reddening of the Mounting on other animals vagina Mucus discharge  Mucus discharges from the vulva Lordosis response  Persistent licking or sniffing the Vulva swelling, pink red vagina of another cow coloring (vulva response)  Mutual chin resting on rump (back) of another animal, rubbing each other  Standing still when mounted by Estrus bull detection Detecting estrus in sheep & goats is relatively easy compared to cattle  Decreased appetite and milk yield Because, heat signs are well pronounced, particularly in goats In control mating (AI) regular detection of estrus is necessary Detection techniques  Visual observation  Teaser bull, ram, buck  Estrus detection techniques in small ruminants Techniques  Using a teaser ram /buck  Using a teaser with a marking harness  Tying apron around body of a ram /buck Using teaser ram or buck Teasers are males animals either vasectomized or epididymized They will detect females in estrus but unable to meet with them Tying an apron Apron made of leather or canvas will be tied around the body of a ram /buck Apron prevents the penis from entering the vagina of females Using teaser with marking harness Harness (marked) will be tied When a ram /buck mounts on a female in estrus, some of the Anestrus/dry period Anestrus is the absence of cycling. Anestrus may occur due to disease, not being of reproductive age, or other conditions. Gametogenesis Key terms  Steroidogenesis  Gametogenesis  Spermatogenesis: spermatocytogenesis and spermiogenesis Steroidogenesis (production of reproductive hormones)  Development of mammary glands  Development of reproductive systems and external genitalia  Fat deposition on hips and stomach (source of energy)  Triggering of heat Gametogenesis  The entire process of producing mature gametes  Spermatogenesis (male)  Ooogenesis (female) Spermatogenesis Process of sperm (spermatozoon) production Rounded immature sperm undergo successive mitotic and meiotic divisions to  Phases of spermatogenesis Time needed to complete spermatogenesis is divided between phases The 3 phase of spermatogenesis: 1) Spermato-cytogenesis (spermatogonia will change to primary spermatocytes) (mitosis) 2) Meiosis (primary spermatocytes will change to spermatids) 3) Spermiogenesis (spermatids will change to spermatozoa) In spermatocytogenesis (metamorphic change) Spermatogonia primary spermatocytes In Meiosis Primary spermatocytes spermatids in Spermiogenesis Sperm morphology Spermatids Sperm components: spermatozoa Head, Mid piece (neck) Tail An entire spermatozoon is covered by plasma lemma (plasma  Head Head incorporates:  Nucleus: contains genetic material, DNA  Post nuclear cap: It covers posterior side of the nucleus  Acrosome: It covers anterior side of the nucleus. Covers the anterior head of sperm nucleus during the last stage of sperm formation. Cap like structure Contains enzymes that involve in the fertilization process  Acrosin  Hyaluronidase  hydrololytic enzyme  Plasma membrane Acrosome (acrosome cap) Double walled structure situated between plasma membrane and anterior portion of sperm head Hyaluronidase: An enzyme found in sperm, sneak venom, bee venom It causes the breakdown of hyaluronic acid in the tissue spaces  Neck of sperm Neck connects sperm head with its tail Some sperm head (flagellum). abnormalities: Tail of the sperm Micro cephalic Has middle, principal (main) and end Macro cephalic pieces. Absent head The end piece contains only the central Amorphous axoneme covered by the plasma membrane. Double head The axoneme is responsible for sperm Abnormal morphology of motility. sperm Three types of abnormal morphology : Primary (abnormal head), Secondary (cytoplasmic droplet) Tertiary (abnormal tails).  All ejaculates have 8-10% abnormal sperm  If abnormal sperm reach 25% fertility will be affected.  Semen Spermatozoa concentrations at Mixture of spermatozoa and ejaculate seminal plasma  Semen= spermatozoa + seminal plasma Semen proportion  Seminal vesicles~ 60% by volume NaHCO3, fructose, coagulating proteins  Prostate gland ~ 35% by volume Citrate, proteins Seminal plasma  Bulbourethral glands~ 4 % by The volume fluid portion of semen Made Alkaline mucus mostly by accessory glands  Some Sperm ~ 1comes fluid % by from volume epididymis & vas deferens The pH of seminal plasma: Bulls & Rams: slightly acidic Boars & Stallions: Slightly alkaline  Components of seminal plasma Inorganic salts - Na, Cl, Ca, Mg and K.  These organic salts helps to maintain osmotic buffering agents (bicarbonate produced by seminal vesicles) Energy substrates (fructose produced by seminal vesicles) Others: Proteins, enzymes &prostaglandin Spermatozoa metabolism Energy for motility is devised from intracellular store of ATP Mitochondria convert fructose to energy (ATP) ATP is used to move the tail of sperms Lipid (plasmalogen) is an energy reserve in spermatozoa and used when other energy sources are limiting.  Factors affecting rate of sperm metabolism Temperature (heat and cold) pH (more acidic or alkaline) Osmotic pressure Concentration of spermatozoa Concentration of hormones Concentration of gases Concentration of light Antibacterial agents Maturation of spermatozoa Two processes of sperm maturation: Epididymal maturation: the sperm gain the ability to be motile, fertile and loss of cytoplasmic droplet Capacitation: the sperm maturation in female reproductive tract  Capacitation…. Starts in the uterus and major site is isthmus of the oviduct  Leads to acrosome changes that lead to sperm penetration of ovum A biochemical change to sperm that allows the true acrosome reaction to occur.  Occurs in the uterus and oviduct.  Time required before sperm can undergo true acrosome reaction Capacitation prevents premature acrosome activation (reaction) It involves enzyme and structural modifications to acrosome & anterior part of the sperm head membrane  The precise During changes involved in capacitation not fully understood capacitation  Secretions removed by female genital tract i.e. removal of cholesterol and changes in ions (Ca++) will occur  Seminal plasma reverses the process of capacitation and the reversing process is called decapacitation Decapacitation factors Glycoproteins from epididymis coat the sperm; Oviductal and uterine fluid remove coat & allow capacitation Folliculogenesis Follicle is ovarian compartment that enables ovary to fulfil its dual functions called gametogenesis and steroidogenesis It is spherical mass of cells containing cavity Oocyte: Is a cell in the ovary derived from oogonium that, upon undergoing meiosis, produce an ovum: (primitive egg in the ovary) Oogenesis: is the production of ova or eggs that takes place in the ovary of the females from a group of cells, the oogonia In oogenesis the ovum is spherical, not motile and much larger with more food reserves and cytoplasm. Folliculogenesis Is the growth & development of the primordial follicle in the ovary. Ovary of new-born heifer may contain up to 100,000 primordial follicles.  100,000 primordial follicles is maximal number of oocytes that the female will ever have in the ovary at birth This number is excess required during life but, only a few of them mature and release an ovum. What determines which primary follicles to develop further during estrous cycle is unknown. Each follicle contains an ovum when follicule goes through stages of recruitment, selection, dominance. During follicular growth, enlargement of oocyte & replication of the surrounding follicular cells increase in number thus, increase the number of layers around the cell. The Oocyte: Surrounded by zona pellucida (non cellular membrane) Suspended in the follicular fluid by cumulus oophorus (a clump of cells)  Types of follicules (development) Primary follicle : Oocyte enclosed by a single layer of flattened follicular cells Secondary follicle: Flattened granulosa cells of the primordial follicle proliferate Tertiary (vesicular) follicle: Granulosa cells secrete a fluid (liquor follicles) which accumulates in the intracellular spaces. Continued secretion or accumulation of liquor follicle results in dissociation of granulosa cells, causing formation of a large fluid filled cavity Graafian follicle: Follicular cells increased in size, Antrum filled with follicular fluid, Oocyte pressed to one side, Surrounded by accumulation of follicular cells (cumulus oophorus). Follicule growth control system  Controlled by neuroendocrine system  FSH is responsible for:  Choice of the primary oocyte and  Membrana granulosa cells to proliferate  to form theca interna (secretes estrogen)  to form theca externa LH in females stimulates:  Ovulation & maturation of graafian follicle Monotocous animals Animals not bearing more than one offspring (one ova per ovulation) Normally having only one offspring per gestation. e.g. horse, some times cow In Monotocous animals  One follicle usually develops more rapidly than others  The rest of the developing follicles regress and form atretic follicles. Polytocous animals Sheep, goat, swine:-  Produce 2 or more offspring per gestation  Have several follicles that develop and ovulate approximately at the same time.  The ova may all come from one ovary, or some may come from each Functions ovary. of follicular fluid 1)Initiate follicular growth (steroidogenesis) 2)Needed for Oocyte maturation, ovulation, egg transport to the oviduct 3)Prepares the follicle for the formation of subsequent corpus luteum 4) Important for sperm metabolism, capacitation, and early embryonic development to takes place (along with oviductal secretions) Maturation of ova and ovulation As a follicle develops it can becomes: Primary Secondary Tertiary Graafian (dominant follicle completing its growth process) Degenerative or atresia (follicle failed of development) During each estrus cycle: Several follicles may develop to graafian stage Only one reaches full maturity It ruptures to release ripe ovum (ovulation) Others become atretic (degenerating, luteinizing or unovulatory follicles) Following ovulation: The cavity of the ovulated follicle is invaded by lutein cells known as corpus luteum They are richly supplied with blood vessels. This structure persists on surface of ovary till few days before next ovulation, Luteolysis (begins to degenerate rapidly) If the animal becomes pregnant CL maintained for the duration of that pregnancy.  Ovulation involves Changes in steroid, gonadotrophin, prostaglandin secretions Alteration in ovarian neuro-musculature Breakdown of the follicular wall, Escape of the ovum and Release of follicular fluid. The ovulation fossa formed after ovulation fills with blood to become the corpus haemorrhagicum and CL (yellow body) protrudes from the surface of the ovary. Two types of Ovulators i) Spontaneous/controlled ovulators Ovulation occurs independent of copulation Mare, cow, ewe, sow Ovulation is controlled by events of estrus cycle and not affected by intromission.  ii) Induced/reflex ovulators Female animals require copulation for ovulation (rabbit, camel, ilama, alpaca) Mature follicles regress if copulation does not occur. Pre-ovulatory surge of GnRh, and subsequent LH surge, is apparently dependent on a neural reflex elicited by vaginal stimulation (intromission) 8. Fertilization It stimulates the surgeand of LH ovulation after stimulation. Cleavage Fertilization: The fusion of sperm cell nucleus with egg cell nucleus to produce a zygote (fertilized egg). Fertilization is the process by which the union of a sperm and an egg occurs called conception.  Conception takes place in the female’s reproductive tract for dogs, cattle, hogs, and many other animals.  Fertilization occurs outside of the body for organisms such as fish.  Fertilization … The ova is viable for approximately 24 hours after ovulation Copulation is act of breeding; intromission, thrusting, and ejaculation.  it triggers oxytocin release from posterior pituitary gland of the female brain  Oxytocin causes contraction of smooth muscle of the female reproductive organs Semen is usually deposited in the upper portion of the vagina.  Spermatozoa transported by swimming, by contractions of uterus and oviducts, and by action of cilia in oviducts Capacitation: serious of changes spermatozoa undergo in the female reproductive tract  Change in ion movement through the cell membranes; increase in cells’ metabolic rates  Release of digestive enzymes from acrosome  Acrosome helps the spermatozoa penetrate through layers surrounding the ovum to accomplish fertilization Large number of spermatozoa find and swarm around the ovum in the oviduct Some begin tunneling through the layers surrounding the ovum  Fertilization requires 3 critical events: 1) Sperm contacts the egg (sperm attachment ) 2) Sperm penetration of zone (sperm or its nucleus enters the egg) 3) Sperm and egg nuclei fuse (fusion of sperm & ovum plasma membranes) 1) Sperm attachment Attachment of the sperm head to the zona pellucida is regulated by receptor sites on the zona surface It is mediated by:  Receptor glycoprotein, and  ZP3 sperm receptor only sperm with intact Acrosome can bind During or just after binding and attachment to the zona, The acrosome spermatozoa undergo a series of events called acrosome reaction. reaction May occur before attachment (after attachment) of sperm head to the glycoprotein receptors on the zona Acrosome intact sperm is essential for attachment. “lock & key" mechanism (such as that for enzyme and its substrate) starts the release of enzyme for penetration  2) Sperm penetration of zone At ovulation zona pellucida surrounds the vitelline membrane of the ovum.  Zona pellucida: membranous structure of the ovum (relatively thick)  Vitelline membrane: cell membrane or plasma membrane of the ovum Granulosa cells surround the zona, and this layer is termed the cumulus oophorus. A specific protein, ZP3, in the zona serves as binding site for spermatozoa Precise structure of this protein varies among species This variation is the main reason why spermatozoa from one species can’t bind to & fertilize Penetration of ova thefrom other zone by species. sperm: Occurs within 5 to 15 minutes after sperm attachment Acrosin is the major zona lysine that acts synergetically with other enzymes during sperm penetration.  3) Gamete fusion Attachment of sperm occurs in the plasma membrane of the sperm head. zone free ova can’t undergo fusion with non acrosome activated sperm even if attachment to membrane surface occurs. The acrosome reaction is a prerequisite for fusion between ova andthe Once spermatozoa plasma zona pellucida membrane is penetrated:  sperm interacts with vitelline membrane in the vitelline space.  Sperm rotates vitelline membrane within the zona  Sperm interacts with dense microvilli that cover vitelline membrane.  Sperm-ovum plasma membranes intermixed &  sperm head undergoes decondensation Sperm lifespan  Block to polyspermy Following fertilization Ovum surface changes to prevent fusion of additional sperm (cortical reaction). Cortical granules are released into the perivitelline space which results in extensive reorganization of the zona pellucida and/or vitelline membrane i.e. hardening of zona and inactivation of ZP3 & ZP2. In other words, Oocyte blocks to polyspermy by:  Zona reaction Mechanisms of blocks:  Vitelline block Sperm attaches to vitteline membrane Cortical granules fuse to vitteline membrane and release contents  Cortical granule components alter zona, i.e. less penetrable by sperm  Vitelline membrane altered i.e. less penetrable by sperm Polyspermy results in polyploid embryos (death or abnormal development) It occurs in 1-2% of mammalian fertilizations. Development of pronuclei and syngamy Pronuclei  nuclei of egg and sperm before immediately before fusing Syngamy  is a process by which genetic material join from each parent  i.e. fusion of nuclei of sperm and egg Fertilization and cleavage Development begins with fertilization of egg (ovum) by a spermatozoon to form a zygote. Ovum & spermatozoon contribute half of nuclear chromosomes to zygote. Cells of zygote undergo division, migration, differentiation to become Morula, Blastula, Gastrula &Embryo Male pronucleus: nucleus of the fertilizing spermatozoon Female pronucleus: nucleus of the fertilizing ovum Each pronucleus contain the haploid chromosome number Male and female pronuclei join together  Restores the diploid chromosome number  Cleavage Process of zygote (one-cell stage) division without an increase in cell mass shortly after fertilization. Sometimes called negative growth. Nuclei do increase in size, proper amount of nucleic acid is maintained in chromosome. Cleavage increases the No. of cells, blastomeres, Without increasing the volume of developing embryo After each cell division, daughter cells have smaller cytoplasmic mass. The nuclei of the daughter cells (blastomere): Are normal Morula in size and Morula: solida mass Contain of cells full complement of chromosomes After fertilization egg undergoes cell division One cell divides into 2, then cleave into 4, those four cells become 8, and so on. When there are hundred or more cells, embryo becomes a solid mass of cells called a Morula Blastula Zona hatching Blastocyst hatching escape from the zona pellucida occurs within the uterine lumen between 4 to 8 days post ovulation. Activation of enzymes such as trypsin and plasmin by the blastocyst and/ or uterus causes softening of the zona allowing the blastocyst to expand and rupture the zona.  Zona hatching … 4 steps must be achieved before embryo can attach to the uterus: 1) Development of embryo within confinement of the zona pellucida 2) Hatching of the embryonic cells (blastocyst) from zona pellucida 3) Formation of extra embryonic membranes (e.g. placenta) 4) Maternal recognition of the pregnancy Zona hatching is caused by: Enzymes (zona lysine) Blastocyst expansion and contraction Estrogens & prostaglandins Zona hatching of species Gastrula It is formation of germ layers (3 cell layers)  Organogenesis Organogenesis is the process of the ectoderm, endoderm and mesoderm developing into internal organs of an organism.  Endoderm: form tissues within the lungs, thyroid and pancreas  Mesoderm: assists in the production of cardiac muscle, skeletal muscles, smooth muscles, tissues within kidneys and red blood cells.  Ectoderm: makes tissues in the epidermis and helps in the formation of neurons in the brain and melanocyte.  Implantation Enzymes produced by blastocyst dissolve away a small pit in the endometrium  Blastocyst attaches to endometrium in this pit In multiparous species, multiple blastocyst randomly space along the horns and body of uterus Placenta begins to form as soon as the blastocyst implants the uterus Zygote survives on yolk and uterine milk (uterine secretions until contact is made between the maternal and the fetal After implantation, embryo develops to fetus obtains membranes) nourishment from it’s dam. This initial contact is called implantation or nidation. Implantation is a gradual process:  Ewe 10 – 18 days  Sow 12 – 24 days  Cow 12 – 30 days  Mare 30 – 60 days Types of Abnormal implantations 1. Ovarian – young seldom survive to full term 2. Tubal – young occasionally survive to birth 3. Abdominal – young do not survive to full term  Placentation  Placenta is formed by the fusion of chorion and uterine mucosa.  It is the development of extra embryonic membranes, or placenta.  placenta is site for exchanges between maternal and fetal circulations  Nutrition from dam can reach fetus and waste products from fetus can be transferred to dam.  Tree primary placental membranes 1. Amnion – innermost 2. Allantois – middle 3. Chorion – outermost  Placenta Multilayered, fluid-filled, membranous sac Outermost layer of placenta attaches to uterine lining where:-  Fetal and maternal blood vessels are in close proximity to each other  Site of exchange of blood, nutrients and wastes Amnion: membranous layer immediately surrounding the fetus  Form the amniotic sac  Fetus floats in amniotic fluid inside the amniotic sac Allantois: layer surrounding amniotic sac; forms allantoic sac, which accumulates wastes Outside of the allantoic sac is covered by the chorion Chorion attaches to the lining of the uterus Chorion is linked to fetus by the umbilical cord.  Yolk sack site of primordial germ cells; contains blood vessels Umbilical cord: two arteries and a vein connects the fetus to the placenta  Placental barrier 1. Prevents large molecules such as antibodies and large amounts of fat soluble vitamins from passing in large from dam to fetus 2. Viruses that are small enough to penetrate the placental barrier can cause defects in young Developing young are susceptible to viral infection because they have not produced their own antibodies 3. Certain other chemical substances in the dams ration penetrate the placental barrier and may cause congenital / inherante defects.  Placenta attachments 1. Diffuse attachments: spread over the whole surfaces of placenta and uterine lining. Eg. Mare and sow/monogastrics 2. Cotyledonary attachment: many small, separate attachment sites (placentomes) e.g. cattle and ewe/ruminants Placentomes: cotyledon on placental surface joins with caruncle in the uterine lining. 3. Zonary attachment: belt-shaped attachment that encircles the placenta e.g., dogs and cats/canines 4. Discoid attachment: placenta and uterus attached at a single disk-shaped area e.g., humans and monkyes i.e., primates  Function of the placenta Transmission of nutrients from dam to young Transmission of wastes fro young to dam Protection of young from shock and adhesions by means of amniotic fluid. Prevention of bacteria and other large molecular substances from dam to young. The secretion of certain hormones; HCG (woman) and PMSG (mare), and progesterone.  9. Gestation, prenatal physiology, and parturition Gestation Pregnancy or gestation is the onset of gestation following fertilization. Gestation period is time from fertilization of ovum to delivery of newborn. Time varies in different species Divided into three segments (trimesters) includes:- First trimester – embryonic period, placenta develops Second trimester – fetal period, body tissues, organs, and systems develop Gestation rates–in Third trimester days fetal growth period  Embryo attachment Embryo Refers to the early period of development where no distinct anatomical structure has formed embryo = from 14 days until 45 days Fetus Potential offspring still in the uterus (before birth) generally recognizable as a member of given species. More advanced from an embryo (46 days onward) In cattle, usually is referred to an advanced embryo after approximately 30 days post-fertilization Parturition Birth process/act of giving birth Multiple factors trigger parturition Size and weight of uterus Hormonal changes  Fetal changes at delivery Lungs expand and start functioning Foramen ovale and ductus arteriosus close  Signs of impending parturition Relaxation of tail head muscles Relaxing /lengthening of vulva Waxing of teats- yellow tinged colostrum Distended abdomen Mammary development & milk secretion Swollen vulva and relaxed pelvic ligaments Mucous discharge Relentlessness and separation from group Labor and Contractions Stages of labor First Stage: uterine contractions  myometrium contracts and presses fetus down against the cervix  Sustained contractions causes the cervix to gradually dilate Second stage: delivery of the new born  Results from combination of strong uterine and abdominal muscle contractions  Rupture of amniotic and allantoic sacs of the placenta usually precedes actual delivery of the newborn Third stage: delivery of the placenta  Placenta separates from the wall of the uterus and is expelled by  Normal parturition Presentation of fetus – forelegs first (breech birth, hind legs first, is normal presentation in goats, swine and sheep) Most cows and mares will lie down prior to expelling calf/foal, if traction is required for delivery, attendant pulls down-toward the dams hocks, not straight out, parallel with the spine Allow neonates to rest with hind legs still in vaginal canal if the umbilical cord is intact. Up to 1 liter of blood may be transferred from the placenta to offspring Neonate should be standing ambulatory and nursing within one hour after birth. Expulsion of placenta/fetal membranes (after birth)cleaning should occur within several hours of birth. Dystocia Membranes thatrisk areof not completely passed within 8-12 hours Factors affecting dystocia represents a medical emergency; retained placenta  Abnormal presentation  Multiple births  Heifers vs cow  Pelvic measurement  Nutritional status – obesity/malnutrition  Involution of the uterus Uterus gradually returns to its nonpregnant size Endometrium sloughs into lumen of uterus at sites of placental attachment Myometrium continues mild contractions to move remaining uterine contents out through birth canal May take from a few weeks to a month or more for involution to beAssisted 10. complete reproductive physiology 1. Estrus synchronization 2. MOET 3. AI 4. Sexed semen or sex fixer  1. Estrous synchronization Definition 1) A management technique which use hormones to control or re- schedule the estrous cycle 2) A reproductive management tool that controls timing of estrus or ovulation 3) Use of hormones that are identical to, or analogs of, the reproductive hormones naturally found in the body 4) The occurrence or induction of estrus in a group of females at the same time (applies only to animals) Estrous synchronization is commonly used especially in the cattle and sheep industries. Estrous synchronization is when producers manipulate the cycles of animals to bring a group into heat at the same time. This can be used to ensure the detection of heat, uniform calving or lambing time, and uniform breeding time. 1. Several different drugs can be used and the timing of shots varies.  Generally, prostaglandin, progestin, or both are used.  Prostaglandin causes progesterone production to stop; this causes estrus to occur. 2. Sheep breeders use controlled internal drug releasers (CIDR) to synchronize ewes.  The CIDR is placed into the vagina and then removed.  This causes them to cycle and can help fertilization to occur during a time of the year when they are not normally cycling. Mechanism Altering length of the estrous cycle and/or pattern of follicular growth Key to Success of the program Efficient and accurate detection of estrus Timely AI relative to time of ovulation Basis for Synchronization of Estrus Manipulate life span of CL Manipulate growth of follicles and timing of ovulation  Purpose of estrus synchronization Group females for parturition:  Decrease labor,  Decrease calving period  Reduce calving season (calves produced early in season will wean heavier because they are older)  Increase calf uniformity (more uniform weaning weights) Reduce (eliminate) estrus detection Shorten breeding season Needed for AI Methods for inducing estrus and synchronizing ovulation Methods with heat detection  Progestin application (MGA, PRID, CIDR)  Deslorelin implant (GnRH agonist)  Prostaglandin (single or repeated PGf2a IM treatment) Timed insemination  Heatsynch (GnRH - PGF2a – ECP)  Ovsynch (GnRH - PGF2a – GnRH)  Provsynch (PGF2a – PGF2a – GnRH - PGF2a – GnRH) starts 35 days Synchronization methods  2. Embryo transfer An embryo is an egg that has already been fertilized by a sperm cell. It is an organism in the earliest stage of development. Embryo Transfer involves the removal of an embryo from a female of superior genetics and the placement of the embryo into the reproductive tract of a female of average genetics. With ET, the donor is super ovulated; a large number of eggs are released due to the application of certain drugs. Fertilization occurs and the fertilized eggs are harvested either surgically or non-surgically. The embryos are then transferred to a recipient or surrogate mother where the embryo develops. The surrogate mother is usually of less value than the donor. Embryos can also be frozen in liquid nitrogen for implantation later, but this is generally not as successful. Allows multiple pregnancies per breeding season Successful reproduction of physical compromised animals Donor female can still compete Recipient dam just carries the baby, shares no genetic material with fetus Used to create number of genetically similar individuals  3. Artificial Insemination Definition: A process by which sperm are collected from the male, processed, stored and artificially introduced in to the female reproductive tract for the purpose of conception. Artificial insemination is the technique in which semen with viable sperm is collected from the male and introduced into the female reproductive tract at the proper time (ovulation) with the help of AI instruments. AI (artificial insemination), also known as AB (artificial breeding), is the physical placement of semen into the reproductive tract of females with the aim of achieving pregnancies by means other than that of natural mating. The process of placing sperm in the reproductive tract of the female is known as insemination. Steps in AI 1. Semen Collection 2. Semen evaluation/ processing the semen 3. Freezing semen 4. Preparing to inseminate 5. Thawing the semen 6. Locating the cervix and First the semen must be collected. 1. An artificial vagina is used with bulls, stallions, boars, bucks (rabbits), and rams to collect the semen.  An artificial vagina is about 10–14 inches long for bulls and about 2.5 inches across.  The outside of the tube is hard with a soft rubbery lining inside.  Warm water is placed between these two linings.  A dummy or other animal is used for the male to mount.  The penis is then directed into the artificial vagina and the semen is collected.  Some animals require the use of an electroejaculator. 2. Tom turkeys and roosters require manual stimulation. Gentle pressure on the abdomen of fish will yield semen. 3. One ejaculation from a bull contains about 5cc of semen; this is enough to breed about 500 cows. A stallion will produce enough to breed only about 17 mares in one ejaculation. 4. The semen is evaluated after being collected to ensure good quality. 5. It is then cooled slowly.  6. Extenders such as egg yolk, antibacterial agents, and other material to add volume to the semen are added. 7. The semen can be stored at 41° F (5° C) for about one week or it is stored at -320° F (-196° C) in liquid nitrogen.  It can later be thawed for use.  Semen frozen in liquid nitrogen can last up to 40 years.  Liquid nitrogen tanks are used to transport semen and for storage on the farm. Timing of insemination The timing of insemination varies greatly by species and can vary between individuals to a degree. 1. Cows are usually inseminating in the evening after showing signs of estrus in the morning or in the morning after showing signs the evening before. 2. Mares are usually inseminated on the third, fifth, and seventh days of estrus. 4. Twenty-four hours after the initiation of estrus sows can be inseminated. Some producers will inseminate the sow after another 24 hour period.  AI Equipment 1. Liquid nitrogen tank to store the semen straws 2. Straw of semen 3. straw tweezers 4. Sterile lubricant (non-spermicidal) to put on the plastic sleeve and/or the animal’s vulva 5. Insemination gun to hold the straw and maneuver it through the cervix 6. thaw box to thaw the straw of semen 7. paper towels to keep the area clean, especially the animal. 8. Scissors to cut the end of the straw just prior to insemination 9. Thermometer to measure the temperature of the water bath Cows10.are artificially Plastic glove orinseminated sleeve to put using on the the recto- inseminator’s arms 1.vaginal method. 11. cover Carefully sheath remove the straw of semen from the liquid nitrogen tank using the tweezers. Be cautious to not burn your fingers. 2. All semen must be thawed before use. Usually a straw is placed in a warm water bath (95–98° F or 33–34° C). Thaw the straw following the recommendations from the company where the semen was purchased. 3. Using a paper towel dry the straw thoroughly. 4. Pull the plunger on the inseminating gun back about 4–6 inches. 5. Insert the straw and cut the end off. 6. Place the cover sheath over the end of the gun and secure. 7. Hold the inseminating gun either in your mouth or have someone else hold it for you.  8. Lubricate the glove with the non-spermicidal lubricant. 9. Insert the gloved arm into the vulva and clean out the rectum. 10. Clean the vulva with the paper towels. 11. Locate the cervix. 12. Using the other hand carefully insert the inseminating gun upward into the vulva to avoid injury. 13. Slide the inseminating gun through the cervix. 14. Deposit the semen into the uterus by pushing the plunger. 15. Slowly remove the inseminating gun. 16. Record the breeding information Placement and method of insemination also vary between species. 1. Instead of inserting the arm into the rectum or mares, it is inserted into the vagina because they have a more delicate rectum.  The semen is also deposited into the uterus. 2. An inseminating tube is placed through the cervix of a sow and a plastic squeeze bottle is used to insert the semen.  Advantages of AI 1. Maximum use is made of outstanding sires. Semen can be used after the sire has died or can be shipped anywhere in the world. 2. Uniformity of offspring is increased. 3. Certain physical handicaps to mating may be overcome. 4. Sire cost can be reduced. 5. Danger and cost of keeping a sire is eliminated. 6. Cost and delays involved in using infertile sire are reduced. 7. Better health is maintained. 8. Breeding herd records are improved. 9. Profits are increased. 10. Pride of ownership is increased  AI limitations 1. Skilled technicians are required. 2. Physiological principles must be followed. 3. Sire market may be limited. 4. Diseases may be spread. 5. May be subject to certain abuses. 6. May accentuate the damage of a poor sire. 7. Artificial breeding organizations require large investments of capital and competent management. 4. Sexed semen What new technologies are being utilized to manage the reproductive success of animals? Many new technologies are available today for producers to consider in optimizing their reproductive program and many more are being developed.  Producers now have the ability to use sexed semen.  Sexed semen is semen that contains only all male or all female sperm.  There is only about a 90% chance that the preferred sex will be produced and the cost of the semen is much higher.  5. Cloning Cloning is one of the newest reproductive management tools available. Through cloning multiple exact genetic copies of an animal are produced. 1. Scientists can clone animals by letting the embryo develop to the 32 cell stage and then split the cells apart.  This is similar to how identical twins are created in nature.  Thousands of clones could be created at one time using this process. 2. Scientists can also take a cell from an adult animal and produce a new cloned off-spring.  This was the process that was used to create Dolly the sheep. 3. Scientists 6. Genetichaveengineering also created cattle by taking primordial germ cells during the development of the fetus. Genetic engineering is the manipulation of the genes of an organism by adding, removing, or modifying the DNA.  This is usually most successful prior to fertilization.  Reproductive failures Sterility, or the inability to reproduce, may be caused by a number of reasons. Permanent or temporary sterility can be the result of specific physical defects, particular diseases, environmental factors, or nutritional aspects. Factors that affect reproductive ability include the following:  Anatomical factors,  Diseases,  Environmental factors, and 1. Anatomical Other factors factors, such as nutrition, toxic plants, and genetic factors. Cryptorchidism – a hereditary condition where both of the testes fail to descend into the scrotum resulting in complete sterility. Unilateral cryptorchidism – a hereditary condition where one of the testes fails to descend into the scrotum resulting in reduced fertility. Scrotal hernia – a condition where part of the intestine passes through the inguinal canal into the scrotum; though it may not cause sterility, a scrotal hernia may cause an animal not to breed and it can be dangerous.  Malformed penis – a condition resulting from injury or birth defect that causes the penis to be malformed to the extent that copulation cannot be performed. Freemartin – a condition with twin calves of the opposite sex, where the female calf’s reproductive tract does not develop completely causing sterility in 90% of the cases. Infantile or absence of ovaries – a condition where the ovaries fail to develop, do not function, or are absent because of a hormone imbalance. 2. Diseases Endocrine disturbances – hormonal or glandular reproductive disturbances Brucellosis orin“Bang’s femalesdisease” resulting– afrom bacterial one ordisease morethat causes cysts on the the destruction ovaries. of the cotyledons of the uterus and may result in abortion of the fetus in latter months of gestation. Preventable by vaccination, brucellosis affects cattle, swine, sheep, goats, horses, dogs, and some wildlife (elk, bison). Infected animals must be slaughtered. Vibriosis (Camylobacteriosis) – a veneral disease found in cattle that causes infertility, early embryonic death, and abortion. Vaccinations are effective at preventing vibriosis. A similar type of organism can infect sheep. Trichomoniasis – a veneral disease caused by a protozoa that infects cattle and causes early embryonic death and abortion. Vaccination is not always an effective means of prevention. Leptospirosis – a bacterial disease that causes a loss of body weight, hemolytic anemia, and abortion. Leptospirosis affects cattle, swine, sheep, goats, dogs, and horses and can effectively be prevented by vaccination.  Infectious Bovine Rhinotracheitis – a respiratory viral disease that causes pneumonia, fever, infertility, impaired fetal circulation, and eventually abortion. IBR can effectively be prevented with vaccinations. Bovine Viral Diarrhea (BVD) – a viral disease that causes ulcerations throughout the digestive tract, fever, and diarrhea. Abortion is caused by infection of cotyledons. Vaccinations are an effective means of prevention of BVD. 3. Environmental factors Mechanical injury – physical damaged to reproductive organs caused by injuries due conditions such as improper handling, unsafe facilities, fighting among animals, or complications during parturition or copulation. Stress – severe climatic conditions (primarily extreme heat), high population density, rough handling, and other stressful environmental factors can cause reproductive distress.  Other factors affecting reproduction Nutritional deficiencies – reproductive inability can be caused by insufficient levels of feed intake and quality of nutrients needed to meet the high demands put on the body’s metabolism due to fertility, pregnancy, lactation, and other events involved in reproduction. Lack of condition or obese condition usually reduces reproductive efficiency. With a lack of condition caused by low nutrition, the body does not have the energy necessary for reproductive activities. During obesity, fatty deposits collect in and around the reproductive organs, impairing function and productivity. The following vitamins and minerals are known to affect reproduction, if they are not balanced in the animal’s diet. Vitamin A – shortened periods of gestation, higher incidence of retained placentas, stillbirths, abortions, mastitis, calves born blind and uncoordinated; Vitamin E – poor conception rates, higher incidence of stillbirths and newborn mortality; Phosphorus – poor conception rates, delayed puberty, lower weaning rates, erratic heat; Calcium – increased calving difficulty, uterine prolapse, retained placenta; Cobalt – poor conception rates, general reproductive failure;  Iodine – retained placentas, delayed puberty, arrested fetal development, irregular or suppressed heat, abortion, stillbirths, and calves that are blind, hairless, and have enlarged thyroid glands; Copper – delayed puberty, abortion, retained placentas; Iron – general reproductive failure, anemic young; and Manganese – irregular or suppressed heat. Ingestion of toxic plants – poisonous plants can also cause reproductive stress or abortion. The following plants can cause abortion and birth defects in cattle: The followingsnakeweed, locoweed, plants can cause abortion inpine. and ponderosa sheep and goats:  Lupines,  Sweet clover,  Onion grass. Genetic factors – some bloodlines are known to have a high genetic factor or weakness for sterility or low productivity. Inbreeding also may result in lowered fertility. Thank you!!!! END