Animal Reproduction Biology Quiz

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Questions and Answers

What is a common environmental factor that can cause reproductive distress in animals?

Severe climatic conditions (correct)

Low-density population

Proper facility management

High nutritional intake

Which disease is NOT effectively prevented by vaccination?

Infectious Bovine Rhinotracheitis

Mechanical injury (correct)

Leptospirosis

Bovine Viral Diarrhea

What effect does obesity have on reproductive efficiency?

Enhances metabolic balance

Improves energy levels

Impairs reproductive function (correct)

Increases fertility

What is the average length of the estrous cycle in cows?

21 days Signup and view all the answers

Which of the following is a symptom of Bovine Viral Diarrhea?

Ulcerations in the digestive tract Signup and view all the answers

Which nutrient deficiency can lead to reproductive inability?

Low energy feed levels Signup and view all the answers

Which phase of the estrous cycle is characterized by a period of sexual receptivity?

Oestrus Signup and view all the answers

During which phase is the active corpus luteum (CL) present?

Metestrus Signup and view all the answers

What type of estrous cycle do polyestrous animals exhibit?

Multiple estrous cycles per year Signup and view all the answers

What percentage of abnormal sperm in an ejaculate can potentially affect fertility?

25% Signup and view all the answers

Which type of abnormal morphology refers to an abnormal head of sperm?

Primary Signup and view all the answers

What is the primary hormone present during the proestrus phase?

Estrogen Signup and view all the answers

In which phase of the estrous cycle does ovulation typically occur?

Estrus Signup and view all the answers

Which accessory gland contributes approximately 4% of the seminal plasma volume?

Bulbourethral glands Signup and view all the answers

Which of the following is true regarding the follicular phase of the estrous cycle?

It is characterized by the regression of the corpus luteum. Signup and view all the answers

What is the main energy substrate for sperm motility derived from seminal vesicles?

Fructose Signup and view all the answers

What physiological change occurs in the body during the proestrus phase?

Secretion of estrogens increases Signup and view all the answers

What is the function of mitochondria in spermatozoa?

To convert fructose to ATP Signup and view all the answers

In which part of the female reproductive tract does capacitation primarily occur?

Isthmus of the oviduct Signup and view all the answers

Which factor does NOT affect the rate of sperm metabolism?

Behavior of the female Signup and view all the answers

Which of the following is a function of the sperm's lipid (plasmalogen)?

Energy reserve when other sources are limited Signup and view all the answers

What is the role of the acrosome reaction in gamete fusion?

It is necessary for the fusion of sperm with the ovum. Signup and view all the answers

What mechanism does the ovum use to block polyspermy after fertilization?

Zona reaction through cortical granule release Signup and view all the answers

What occurs immediately after the sperm and ovum nuclei fuse?

Development of the zygote Signup and view all the answers

Which component is involved in altering the zona pellucida to block polyspermy?

Cortical granule components Signup and view all the answers

What does the term 'syngamy' refer to in fertilization?

Fusion of the nuclei from sperm and egg Signup and view all the answers

During which process does a zygote undergo division without an increase in cell mass?

Cleavage Signup and view all the answers

What is the primary result of polyspermy during fertilization?

Polyploid embryos leading to abnormal development Signup and view all the answers

How does the sperm interact with the vitelline membrane during fertilization?

By rotating the vitelline membrane within the zona Signup and view all the answers

What is the primary function of the placenta during pregnancy?

Facilitates exchange of nutrients and wastes between maternal and fetal circulations Signup and view all the answers

Which placental membrane is the innermost layer surrounding the fetus?

Amnion Signup and view all the answers

During implantation, what is the role of enzymes produced by the blastocyst?

To dissolve a small pit in the endometrium for attachment Signup and view all the answers

Which type of abnormal implantation typically results in young that seldom survive to full term?

Ovarian Signup and view all the answers

What is the term for the initial contact between the embryo and the uterine environment?

Implantation Signup and view all the answers

Which structure connects the fetus to the placenta, containing two arteries and a vein?

Umbilical cord Signup and view all the answers

What role does the allantois play in fetal development?

It accumulates fetal waste products Signup and view all the answers

Which option correctly describes the development timeline of implantation in cows?

12 – 30 days Signup and view all the answers

What is the average length of estrus in sows?

3 days Signup and view all the answers

Which of the following is NOT a behavioral sign of estrus in a doe?

Increased wool growth Signup and view all the answers

What is the typical ovulation window after the start of estrus in does?

21 - 36 hours Signup and view all the answers

What is the recommended lambing/kidding interval under normal circumstances?

8 months Signup and view all the answers

Which estrus detection technique is least likely to show accurate results?

Automated monitoring system Signup and view all the answers

What is the primary purpose of using a teaser ram or buck?

To detect females in estrus Signup and view all the answers

How many ova can be shed during one estrous cycle in sows?

11 - 24 Signup and view all the answers

Which condition describes the absence of cycling in females?

Anestrus Signup and view all the answers

In which season do most conceptions in sheep and goats occur in the Ethiopian highlands?

Short rains Signup and view all the answers

Which of the following is a sign that a ewe is in estrus?

Decreased appetite Signup and view all the answers

Reproductive Physiology and Artificial Insemination (AI) in animal

Signup and view all the answers

Study Notes

Reproductive Physiology and Artificial Insemination (AI)

Reproduction is the process by which organisms produce more of their own kind.
Offspring are produced by male and female parents.
Reproduction involves heterosexual mating, conception, pregnancy, parturition and lactation.
Reproduction requires close coordination of various physiological events.
Two types of reproduction exist: sexual and asexual.
- Sexual reproduction involves the fusion of sperm and egg.
- Asexual reproduction does not involve the fusion of gametes.

Sexual Reproduction

Offspring cells have two sets of chromosomes (one from each parent).
Sexual reproduction involves two stages: meiosis and fertilization.
- Meiosis is a special type of cell division.
- Fertilization is the fusion of two gametes.
Two types of fertilization exist:
- External - fish
- Internal - mammals and birds
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, and regeneration.

Mitosis

Exact duplication of the nucleus of a cell to form two identical nuclei during cell division.

Binary Fission

Occurs in single-celled organisms (e.g., amoeba, paramecium).
Nucleus divides via mitosis, then the cytoplasm divides, forming two new daughter cells of equal size.

Budding

Occurs in hydra and yeast.
Cytoplasm divides unequally, with one daughter cell larger than the other.
Daughter cells can separate or remain attached.

Sporulation

Occurs in molds.
Spores produced in large numbers by mitosis.
Spores are surrounded by a tough coat for survival in harsh environments.
Spores can develop into new individuals.

Regeneration

The replacement or regrowth of lost or damaged body parts.

Parthenogenesis

Development of an unfertilized egg into a new individual that is a clone of the parent.
Includes bees, wasps, ants, and some birds and lizards.

Male Reproductive Tracts and Physiology

Primary sex organs: testes and scrotal sac (suspended by spermatic cord).
Secondary sex organs: duct tissues (transport sperm) including efferent ducts, epididymis, ductus deferens (vas deferens), urethra and penis.
Accessory sex organs: prostate gland, seminal vesicles, and bulbourethral (Cowper's) glands.
Testes (singular: testis): sperm-producing organ, held in the scrotum.
Scrotum: heat-regulating mechanism for normal sperm formation. Optimum temperature for spermatogenesis (sperm development) is 4-5°C below body temperature.
Testes functions: produce testosterone (Leydig cells) and spermatogenesis (seminiferous tubules)

Functions of Testes

Produce testosterone (Leydig cells).
Site of spermatogenesis (seminiferous tubules).

Male Reproductive Systems

Diagrams of bull, boar, ram, and stallion reproductive systems are shown.

Epididymis

Flat and convoluted structure, attached to one side of the testicle.
Stores sperm (mainly in the tail) for up to 60 days, maintaining motility and fertility.
Absorbs sperm during prolonged sexual rest.
Releases protoplasmic droplet from some sperm.
Secretes glyceryl-phosphorylcholine (metabolized in the female genitalia for energy during capacitation).
Divided into three regions (caput, corpus, and cauda epididymides).

Vas Deferens

Transports sperm from the epididymis to the urethra.
Contains a large number of sperm equal to an ejaculate.
Provides nutrients to stored sperm to maintain viability, motility and fertility for up to 3 days after an ejaculate.
May absorb dead sperm.

Penis

Organ of insemination.
Consists of three parts (root, body, glans).
Mainly composed of erectile tissue.
Forms an S-shaped curve (sigmoid flexure) behind the scrotum.
Retractor muscles hold the penis in an S-shape.
Straightens during erection.
Sterility can result if sigmoid flexure doesn't work correctly.

Urethra

Begins at the opening of the bladder and is continuous with the penis.
Posterior portion is S-shaped (sigmoid flexure).
Extends the penis outside the body and into the vagina of the female.
Strong retractor muscles hold the penis in the S-shaped configuration, and are straightened during erection.

Prepuce

Tubular integument that covers the free portion of penis (30-40 cm long) in most males.
Tubular glands secrete smegma to modulate prepuce condition.
Function is to protect the penis.

Accessory Glands

Prostate gland: only gland common to all mammals.
- Located at the neck of the urinary bladder.
- Relativley small in bulls.
- Secretes a large volume of minerals to regulate seminal plasma buffering, amino acids for sperm nutrition.
- Provides alkaline secretion to neutralize acidic sperm from the cauda epididymus and assists in delivering sperm to the seminal glands.
Seminal vesicles: lie on either side of the neck of the bladder;
- Secretes main volume of seminal plasma (>50%) acting as a vehicle for sperm activity.
- Secretes fructose for sperm energy.
- Secretes citric acid as a buffer for sperm.
- Secretes K and iron to control osmotic pressure.
- May secrete flavin which gives yellow coloration to ejaculate in some
Bulbourethral (Cowper's) glands: small, firm glands;
- Located on either side of the urethra, behind the prostate.
- Secretory duct to pelvic urethra.
- Flush, clean and neutralizes the urethra of any urine residue (which may be harmful to spermatozoa).
- Secrete clear secretion during sexual excitement prior to service, contained with various fluids (NaCl, KCl, Nitrogen, citric acid, fructose, and several vitamins.)

Female Reproductive Tracts and Physiology

Vulva: external vertical opening of genital tract below anus.
Vestibule: part of the reproductive tract shared with the urinary system, common duct for urine and reproduction.
Vagina: copulatory organ, lies between cervix and vulva; responsible for secretion of mucus, admits the male organ during copulation. Transports or temporarily stores sperm, serves as birth canal, defense against bacteria invasion.
Cervix uteri (neck of the womb): lies between vagina and uterus; produces mucus; acts as reservoir for semen and selector of viable sperm. Important for preventing non-viable sperm further in the reproductive tract.
Uterus (womb): hollow muscular organ, consists of a body and two horns (bicornuate - pig / bipartite - cow).
- Myometrium - inner circular smooth muscles of the uterus;
- Endometrium - innermost lining; provides point of placental attachment. -Perimetrium - outer serosal layer (continuous with peritoneum), blocks adhesions or linkages
Fallopian tubes (oviducts): connects uterus to ovaries, composed of three parts (infundibulum, ampulla, isthmus) which catches and transports ovulated eggs to the uterus. Ovulation occurs in the oviduct. Site of fertilization.

Ovaries

Primary reproductive organs of females.
Suspended from the broad ligament.
Appearance of surface changes (follicle growth, ovulation, regression).
Produce the female egg or ovum (gametogenesis).
Produce hormones (steroidogenesis): estrogen, progesterone, inhibin, relaxin, oxytocin.
Ovaries contain thousands of ova, surrounded by a layer of cells (follicles), which grow and appear as blisters.
As follicles enlarge, they appear as large blisters on the surface of the ovaries and can be detected by rectal palpation.

Ovulation

Development of ovulatory follicles begins at puberty.
Majority of follicles regress without releasing ova.
After ovulation, the walls of the follicle collapse and develop into corpus luteum (CL).
CL reaches its maximum size 10-12 days after ovulation.
If pregnancy does not result, the CL regresses 3-4 days before the next ovulation .
Presence of embryo in uterus prevents the CL from regressing

Reproduction Hormones

Organic substances secreted by specialized cells (glands) that diffuse to other parts of the body and initiate reproductive changes.
Produced from various sources: hypothalamus, pituitary, gonads, uterus, placenta.
- Hormones in production: Luteinizing hormone (LH) , follicle-stimulating hormone (FSH), estrogen, progesterone, prostaglandins, inhibin, oxytocin & relaxin.

Primary Hormones

Directly involved in various aspects of reproduction.
- Spermatogenesis, oogenesis, and ovulation.

Secondary Hormones

Indirectly influence reproduction.
Needed for normal functioning of organs for reproduction.

Neuroendocrine Reflex

Nervous system releases hormones through neural pathways (e.g, oxytocin in milk let-down, LH release following copulation).

Immunological Endocrine Control

Endocrine and immune systems extensively interact.
Several endocrine organs are regulated by immune function.
Mating behavior in farm animals affected by immune functions.
Strong drive to make decisions about mating behavior.

Mating Behavior

Males compete for access to females.
Females are selective in choosing mates.
Cattle behave in an agitated manner to attract bulls as ovulation approaches.
Cow/cow mounting is common in dairy herds without bulls.
Bull defends cow from other bulls.
Bull's guarding and chasing of other bulls; preventing female cow from rejoining the herd.
Cow remains behind bull.
Bull stands in inverse polar position.
Heat in cow is relatively easy and is characterised by; restlessness, bellowing, swelling and reddening of vulva, mucus discharge, consistent licking of vulva by other animal, chin resting on each others rump and rubbing each other.
Estrous detection(techniques - sheep): using a teaser ram/buck in harness, tying apron around body of the animals,
Estrous detection(techniques - cows): Visual observation using teaser bull, rams or bucks.
During heat, animals may exhibit restlessness.

Estrous and Estrus Cycles

Puberty - stage of sexual maturity
Estrous cycle - period from one estrus to the next.
Estrous cycle length varies between species.
- Cattle: 21 days ( 18-22 days heifers /18-24 days cows),
- Swine: variable
- Sheep: 17 days,
- Goats: variable,
Monoestrous (seasonal breeders): Animals that have only one estrous cycle per year.
Polyestrous : Animals that have several estrous cycles per year.
Duration of estrus: normal range is 12-24 hours, in zebu (Bos Indicus) it's 10 hours / 11-15 in Bos Taurus.
Ovulation occurs about 10-14 hours after the end of estrus.
Time of breeding: bovine spermatozoa must present for at least 6 hours in the uterus for fertilization.

Phases of Estrous cycle

Follicular phase (proestrus & estrus): period from CL regression and formation of the new CL of the following cycle; lasts about 3-6 days.
Luteal phase (metestrus & diestrus): period of CL activity; begins from CL formation 5-6 days after onset of estrus; ends when CL regresses
Duration: 17-19 days after estrus.
Proestrus is the phase immediately before estrus, and lasts roughly 2-3 days.
Metestrus is the phase post-ovulation and lasts for 3-6 days.
Diestrus is the phase when the CL is fully developed; 13 days post estrus.

Estrous Cycle Phases Continued

Proestrus: 1st phase; begins to secrete estrogens;
Decreases progesterone level in blood, vascularity rises and growth of tubular genitalia for next estrus and pregnancy.
Estrus: 2nd phase ; increase in estrogen and decrease in progesterone; causes changes in cow's behaviour and attracts bulls; fluids provide favourable environment; ovulation occurs at this time for fertilization.
Metestrus: 3rd stage; occurs after estrus. Mucus becomes sticky, and colour changes to yellowish/brown; estrogens decrease, progesterone increases. External genitalia returns to its pre-estrus state.
Diestrus: 4th stage ; occurs after metestrus and lasts about 13 days.; CL is fully developed; endometrium becomes thicker and uterine glands increase in size.

Infertility Factors

Anatomical factors: malformed penis, freemartinism, infantile or absence of ovaries (hormone imbalance.)
Diseases: endocrine disturbances (brucellosis - abortion), Vibriosis (causes infertility, embryonic death & abortion), Trichomoniasis (venereal disease from protozoa that cause infertility & abortion), Leptospirosis (body weight loss, hemolytic anaemia and abortion). Infectious Bovine Rhinotacheitis (IBR) (respiratory viral disease causing abortion)
Environmental factors: mechanical injury (improper animal handling, unsafe facilities), high population density, rough handling,
Nutritional Factors: lack of condition or obese condition (low nutrition causes lack of reproductive energy); Vitamin A deficiencies (shortened gestation, higher incidence of retained placentas, stillbirths & abortions); Vitamin E deficiencies (poor conception rate, stillbirths & newborn mortality), phosphorus (poor conception rates, delayed puberty, lower weaning rates and erratioc heat), calcium (increased calving difficulty, uterine prolapse, retained placenta), cobalt (poor conception rates, general reproductive failure), iodine (retained placenta, delayed puberty & arrested fetal development), copper (delayed puberty, abortion and retained placentas), Iron (general reproductive failure & anemic young) and Manganese (irregular or suppressed heat.)
Ingestion of toxic plants can cause reproductive stress or abortion.

Artificial Insemination (AI)

Technique for introducing semen into a female reproductive tract.
Involves collecting male semen, processing it, and introducing it into a female at the appropriate time (ovulation) using instruments.
Advantages
- Maximum use of outstanding sires.
- Uniformity of offspring.
- Overcomes physical mating handicaps.
- Reduction of sire cost.
- Avoids infertile sires.
- Improves herd health.
- Increased profits.
Disadvantages
- Skilled technicians are required.
- Physiological principles must be followed.
- Sire market may be limited.
- Diseases can be spread.
- Can be subject to abuse
- Can accentuate the damage of a poor sire.

Cloning

Creates exact genetic copies of an animal.
Techniques: Scientists can split the cells of an embryo that has been allowed to develop to the 32nd cell stage to create many identical twins. Scientists can take a cell from an adult animal and produce a new cloned offspring (as in Dolly the sheep). Using genetic engineering techniques can manipulate primordial stem cells in the developing fetus.
Usually most successful prior to fertilization.

Reproductive Failures

Sterility (inability to reproduce).
Physical defects.
Diseases.
Environmental factors.
Nutritional imbalances.

Implantation

Stage when blastocyst attaches to endometrium of the uterus.
Enzymes produced by blastocyst dissolve a small pit.

Placenta

Formed by the fusion of chorion and uterine mucosa.
Site of exchange of blood, nutrients, and wastes between the mother and the fetus, and for production of hormones.
Three primary membranes: amnion, allantois, chorion.
Types of Placenta: diffuse, cotyledonary, zonary, discoid.

Parturition

Birth process
Multiple factors trigger parturition
- Size and weight of the uterus.
- Hormonal changes.
- Fetal changes at delivery (Lungs expanding, foramen ovale and ductus arteriosus closing).

Parturition Continued

Signs of impending parturition:
- Relaxation of tail head muscles.
- Lengthening of vulva.
- Waxing of teats (yellow tinged colostrum).
- Distended abdomen.
- Mammary development and milk secretion.
- Swollen vulva and relaxed pelvic ligaments.
- Mucous discharge.
Labour stages:
- First stage: uterine contractions that push the fetus against the cervix gradually dilating.
- Second stage: delivery of newborn through uterine and abdominal muscle contractions.
- Third stage: delivery or expulsion of placenta.

Normal Parturition

Presentation of fetus- fore legs first (breech birth, hind leg first is normal presentation in goats & swine.)
Allow neonates to rest with hind legs still in canal of vagina
Expulsion of placenta/fetal membranes (after birth/cleaning) several hours after birth.

Extrous detection techniques in small ruminants

Using a teaser/buck/harness
Tying apron around body
Tying harness (marked)

Estrous Synchronization

Management technique to control or reschedule the estrous cycle.
Uses hormones identical to or analogs of reproductive hormones.
Used to synchronize a group of animals in heat for uniform breeding time, calving and lambing.
Methods use prostaglandins to stop progesterone production, which releases the estrous cycle.

Embryo Transfer

Transfer of fertilized eggs (embryos) from the reproductive tract of a superior female (donor) to another female reproductive tract (recipient).
Donor is super ovulated.
Embryos are either harvested surgically or non-surgically.

Other factors

Nutritional: insufficient levels of feed and quality, lack of condition or obese condition, fatty deposits.
Environmental: mechanical injury, high population density, rough handling, stress.

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Test your knowledge on various aspects of animal reproductive biology with this quiz. You will explore topics such as estrous cycles, reproductive efficiency, and the impact of environmental factors on fertility. Perfect for students and professionals in veterinary medicine and animal sciences.