past exams

Question 1

What effect would administration of testosterone have on a castrated male?
a. Reduction in size of the accessory sex glands
b. Release of endogenous inhibin
c. Increase in libido and display of courtship behaviours
d. Increased GnRH production

Answer 1

c. Increase in libido and display of courtship behaviours

Question 2

Which scenario is most consistent with normal parturition?
a. A ewe who births the placenta 18 hours after delivering a lamb
b. A mare in 2nd stage labour with abdominal straining for 2 hours
c. A cow in 2nd stage labour with abdominal straining for 1 hour, where the front legs and muzzle of the calf are visible
d. A bitch with a large litter in 2nd stage labour, who initially birthed 2 puppies in an hour, but has not birthed any further puppies for the last 4 hours

Answer 2

c. A cow in 2nd stage labour with abdominal straining for 1 hour, where the front legs and muzzle of the calf are visible

Question 3

Which correctly describes the anatomy of the root of the penis?
a. Paired crura containing corpora cavernosa, surrounded by the ischiocavernosus muscles
b. A single crus containing corpus spongiosum, surrounded by ischiocavernosus muscle
c. A single bulb containing corpora cavernosa, surrounded by the bulbospongiosus muscle
d. Paired bulbs containing corpus spongiosum, surrounded by the bulbospongiosus muscle

Answer 3

a. Paired crura containing corpora cavernosa, surrounded by the ischiocavernosus muscles

Question 4

What is the function of fimbriae on the infundibulum?
a. To move embryos through the isthmus
b. To catch oocytes during ovulation
c. To keep sperm within the oviduct for fertilisation
d. To restrict the exit of embryos into the uterus

Answer 4

b. To catch oocytes during ovulation

Question 5

What effect would a short series of injections of follicle stimulating hormone (FSH)
have on a 2 month old heifer calf?
a. Acceleration of puberty if the bodyweight threshold has been attained
b. An increased number of oocytes being ovulated during the first estrus of puberty
c. Regression of any antral follicles on the ovary
d. Stimulation of follicle development and growth of multiple ovulatory follicles

Answer 5

d. Stimulation of follicle development and growth of multiple ovulatory follicles

Question 6

Given when ovulation occurs in the sow’s estrous cycle, when would be the ideal
time to inseminate to achieve maximal fertility?
a. Immediately upon showing signs of estrus
b. 12 hours after first showing signs of estrus
c. 24-36 hours after first showing signs of estrus
d. 24-36 hours after estrus has concluded

Answer 6

c. 24-36 hours after first showing signs of estrus

Question 7

How would a recipient ewe need to be prepared for an embryo transfer?
a. Given a CIDR at transfer
b. Given a CIDR and PMSG at the same time as the donor ewe
c. Given multiple injections of FSH at the same time as the donor ewe
d. Given PGF2alpha at transfer

Answer 7

b. Given a CIDR and PMSG at the same time as the donor ewe

Question 8

8: Where and when would you collect an expanded blastocyst from a cow?
a. Uterine horn, day 7
b. Oviduct, day 6
c. Uterine body, day 16
d. Ampulla, day 10

Answer 8

a. Uterine horn, day 7

Question 9

What is the CORRECT order of events around fertilisation?
a. Hyperactivated motility > formation of sperm reservoir at UTJ > acrosome reaction >
completion of capacitation > syngamy > cleavage
b. Hyperactivated motility > completion of capacitation > formation of sperm reservoir at UTJ >
syngamy > acrosome reaction > cleavage
c. Completion of capacitation > formation of sperm reservoir at UTJ > acrosome reaction >
hyperactivated motility > cleavage > syngamy
d. Formation of sperm reservoir at UTJ > completion of capacitation > hyperactivated motility >
acrosome reaction > syngamy > cleavage

Answer 9

d. Formation of sperm reservoir at UTJ > completion of capacitation > hyperactivated motility >
acrosome reaction > syngamy > cleavage

Question 10

Why is laparoscopic insemination used in sheep?
a. To guide an inseminating pipette through the cervix
b. To bypass the cervix and deposit semen in the uterus
c. To improve pregnancy rates for fresh semen
d. To deposit frozen sperm in the oviduct

Answer 10

b. To bypass the cervix and deposit semen in the uterus

Question 11

Which of these is NOT a definitive sign of pregnancy by rectal palpation?
a. Fetal membrane slip
b. Placentomes
c. Amniotic vesicle
d. Weight of the uterus

Answer 11

d. Weight of the uterus

Question 12

At what stage of pregnancy are you able to feel an amniotic vesicle by palpation?
a. 20-50 days of gestation
b. After 75 days of gestation
c. 35-90 days of gestation
d. 70-90 days of gestation

Answer 12

a. 20-50 days of gestation

Question 13

What would you observe in vaginal cytology from a bitch in proestrus?
a. Mostly parabasal cells
b. Mostly cornified cells
c. Some intermediate and some parabasal cells
d. Some RBCs and some cornified cells

Answer 13

d. Some RBCs and some cornified cells

Question 14

Which hormonal shift late in pregnancy is important for subsequent lactation?
a. Drop in placental lactogen
b. Drop in progesterone
c. Drop in estrogen
d. Increase in placental prolactin

Answer 14

b. Drop in progesterone

Question 15

Which hormonal change drives the process of uterine involution post-partum?
a. Limited LH pulse frequency
b. Significant drop in progesterone
c. Increased GnRH pulsatility
d. Intermittent oxytocin release

Answer 15

d. Intermittent oxytocin release

Question 16

What is the major difference in the hypothalamus between males and females
which develops prenatally?
a. In males, surge centre is defeminised due to E2
b. In males, surge centre develops due to T
c. In females, surge centre is feminised due to E2
d. In females, surge centre develops due to E2

Answer 16

a. In males, surge centre is defeminised due to E2

Question 17

You give a drug which arrests developing sperm after the first meiotic division.
Which cell type will be ABSENT from the testis?
a. Spermatids
b. Spermatogonia
c. Primary spermatocytes
d. Secondary spermatocytes

Answer 17

a. Spermatids (?) or secondary spermatocytes?

Question 18

Which species do not have all 4 accessory sex glands?
a. Boar, dog and tom
b. Bull, boar and dog
c. Stallion, dog and tom
d. Bull, ram and boar

Answer 18

a. Boar, dog and tom

Question 19

We know that fertilisation of the avian egg occurs in the infundibulum within 15
minutes after ovulation. How do birds manage to have semen in the infundibulum at the precise
time of ovulation?
a. The male bird detects pheromones and body language signals to ensure that mating occurs
with enough time for sperm to arrive at the infundibulum within that 15 minute window
b. Semen is stored in the infundibulum wall and released by the hormonal changes associated
with ovulation
c. Semen is stored in vaginal crypts and released during oviposition, reaching the infundibulum
in time to fertilise the newly released ovum
d. Because avian semen has high density and motility, so long as the birds mate regularly each
day there is always semen in the infundibulum

Answer 19

c. Semen is stored in vaginal crypts and released during oviposition, reaching the infundibulum
in time to fertilise the newly released ovum
?????

Question 20

Some snakes are ovoviviparous, meaning they deliver live young. How are these
young maternally supported before birth?
a. Placental attachment to the uterine wall
b. Uterine fluid in which the young are suspended
c. A soft-shelled egg-like structure that contains yolk and albumen
d. Direct attachment to the uterine wall and the mother’s blood supply

Answer 20

c. A soft-shelled egg-like structure that contains yolk and albumen

Question 21

Describe the signal for maternal recognition of pregnancy in the cow and sow, and how this
differs in the bitch

Answer 21

Ruminant:
Conceptus secretes interferon tau (IFNT) → blocks expression of oxytocin receptors in uterine epithelium → blocks production of PGF2a → no signal for luteolysis → CL is maintained
IFNT also promotes uterine gland secretion (supports developing conceptus) and can influence maternal immune response

Sow:
Conceptus secretes estradiol (E2) → causes “rerouting” of PGF2a unto uterine lumen (exocrine) instead of uterine vein (endocrine) → PGF2a breaks down in lumen → no signal for luteolysis → CLs are maintained
Minimum of 2 conceptus in each uterine horn is required to generate enough signal to prevent luteolysis

Bitch (Carnivores):
CLs last for the entire length of gestation, even if there is no pregnancy
No specific signal required for maternal recognition of pregnancy

Question 22

List FIVE major causes of neonatal mortality in cattle

Answer 22

Dystocia
Disease
Congenital malformations
Mismothering / starvation
Hypothermia

Question 23

Compare placentation in the cow and bitch, including:
* Describe the type of placenta each has, in terms of fetal/maternal separation and chorionic villi
distribution
* Draw labelled diagrams, showing the 3 placental layers and chorionic villi for each species
* Describe when placental takeover of P4 production occurs

Answer 23

Cow:
Cotyledonary placenta
Discrete round patches of villi form cotyledons on the chorion that connect to endometrial convex caruncles
Epitheliochorial placenta
Least invasive
6 layers between mom and baby

Bitch:
Zonary placenta
Prominent round transfer zone of highly invasive villi form a central band
Edges of band form a pigmented zone that contains haemmorhage and necrotic tissue
Endotheliochorial
Slightly more invasive than the cow
5 layers (NO endometrial epithelium present)

• Describe when placental takeover of P4 production occurs
  Cow = 6-8 months
  Bitch = none

Question 24

You are working for a mixed practice and head out to a sheep property to perform
breeding soundness exams prior to paddock joining. The farm is in a high rainfall area, and the
pastures are lush. The rams at this property have been trained for semen collection with an
artificial vagina.
a. List FIVE things that are included in a male breeding soundness exam

Answer 24

● General Physical Exam (BCS, Vision, Denitition, Musculoskeletal disorders)
● Reproductive Physical Exam (Accessory sex glands, Scrotum contents, prepuce,
measurement of scrotal circumference)
● Semen Collection + Evaluation (Motility, Concentration, Morphology)
● Service Capacity Testing
● Testing for Infectious of Genetic Diseases

Question 25

Describe how you would assess semen quality of a fresh ram ejaculate

Answer 25

Semen volume Measured roughly (tube mark) or accurately (cylinder or pipette) Semen color /consistency Assessed qualitatively Semen motility Assessed subjectively (by user) or objectively (by computer) using a phase contrast microscope - Total motility = % of sperm with any movement - Progressive motility = % of sperm with strong forward movement - Can also assess Wave Motion based on a 0 (no movement) to 5 (rapid movement) scale Semen morphology Assessed subjectively using either a differential interference contrast (DIC) or stain Can be basic (% of sperm with abnormalities), intermediate (% of sperm with head and/or tail defects), or advanced (% of sperm with folded tail and/or knobbed acrosome) Semen concentration Measured objectively either manually (haemocytometer) or automatically (spectrophotometer)

Question 26

Describing the 3 steps of spermatogenesis

Answer 26

● Step 1: Mitosis - Spermatogonia undergo mitosis to create more genetically identical diploid (2n) cells - Creates a continual supply of cells for meiosis ● Step 2: Meiosis - Primary spermatocytes undergo meiosis I to form Secondary spermatocytes - Secondary spermatocytes undergo meiosis II to form spermatids - Creates genetic diversity by reducing cell form from diploid (2n) to haploid (1n) ● Step 3: Spermiogenesis - Round spermatids undergo spermiogenesis to form elongated spermatids that eventually mature into spermatozoa - Creates mature sperm structure/function - Process includes 1. Golgi = acrosome vesicle formation 2. Cap = spreading of acrosome vesicle over nucleus 3. Acrosomal = nuclear/cytoplasmic elongation 4. Maturation = cytoplasmic shedding + final structural assembly

Question 27

Explaining how to calculate the length of time to wait before re-testing semen after recovery from a fever

Answer 27

You need to determine the spermatogenic cycle (which is the epithelium cycle x 4.5) and then factor in the epididymal transit time which is around 2 weeks across all species - ex in ram: Spermatogenic cycle = 10.1 x 4.5 = 45.45 days - Spermatogenic cycle + epididymal transit time = 45.45 days + 14 days = 59.45 days - Retest the semen in about 59-60 days post fever

Question 28

Listing THREE factors which could negatively impact spermatogenesis in the rams on this property

Answer 28

Factors that impact spermatogenesis: Breakdown of blood-testis barrier Diet Irradiation Excess heat Drugs/toxic agents Disease Endocrine disruption On this particular farm, with lush pasture, the three factors that would most likely be impacting these particular rams would be (I think): Diet Heat stress Endocrine disruption

Question 29

Explain why the ideal time during estrus to inseminate a ewe and bitch differs (5

Answer 29

For insemination, the oocytes must be fertilised within 10-12 hours post-ovulation and need to remember that sperm also needs several hours for capacitation. Ideally sperm would already be in the reservoir prior to ovulation. Ensures that capacitated, viable sperm is available when an oocyte enters the ampulla. Sheep Once P4 is removed, Estrus will begin within 24-48 hours and it will last for around 30 hours. Ovulation will occur 24-30 hours once estrus starts. You would want to inseminate a sheep around 28 hours after estrus starts so that the sperm is already there when oocytes are released from ovulation Dog Estrus last around 9 days for a female dog, and ovulation will occur about 3 days after estrus begins. However, fertilisation occurs 5-6 days after estrus beings, so would need to be inseminated after ovulation. The dog is the exception because several days are required for oocyte maturation, so sperm needed post ovulation for the dog, while in the sheep it is needed before ovulation occurs

Question 30

Compare the phases of initial and cyclic recruitment, including: * A definition of the phase * When it occurs * The steps of folliculogenesis it includes * The hormonal drivers

Answer 30

Folliculogenesis (ie. development of follicles) is broken into 2 distinct phases: Initial Recruitment Phase Includes primordial → primary follicle → secondary follicle → tertiary (antral) follicle Continuous throughout the female’s life (even before puberty) Likely under paracrine/autocrine control Takes ~100 days Cyclic Recruitment Phase Includes antral follicle → ovulating follicle Occurs during EACH cycle Driven by FSH/LH Takes ~10 days (species dependent)

Question 31

You are working at an equine breeding facility, where you are responsible for meeting annual foal production targets. Pregnancy losses are higher than normal this year. The barn air conditioning has broken down, so the horses are often turned out in hot weather. a. Describe the estrous cycle of a mare, including length, seasonality and indicators of estrus

Answer 31

Long day breeders (ie. mate during spring/summer and will breed in the next autumn) Cycle length is 21 days Estrus lasts 7 day Ovulation starts 5 days after beginning of estrus Spring Transition: occurs before the breeding season - involves 3-4 periods of estrus behaviours WITHOUT ovulation Estrus Behavioural Indicators:: Locomotion (restlessness/roaming) Urination in front of stallion Clitorial winking Tail flagging Standing to be mounted Vocalisation Estrus Physiological Indicators: Red, swollen vuvle Thin, clear mucus discharge Increased uterine tone Thickened vaginal epithelium

Question 32

Outline when pregnancy loss is most likely to occur AND describe THREE possible causes of pregnancy loss in these mares

Answer 32

Pregnancy loss is most likely to occur during the early embryonic stage (ie. early in pregnancy) Common causes of fetal loss include: Infection (bacterial, viral, fungal, protozoan) Genetic abnormalities Toxins Endocrine disruption Nutritional deficiency Uterine crowding Anatomical deficiencies Trauma and stress In this particular question, I think the most likely three causes for pregnancy loss in these horses would be: Heat stress Nutritional deficiency Environmental and handling-related trauma/stress

Question 33

Explain what ‘foal heat’ is, why it is unique to horses, and what advantage it has at this facility

Answer 33

Most species need a prolonged period for uterine involution before the next estrus cycle can occur, however the mare’s uterus involutes rapidly, allowing her to return to estrus while she is still nursing her foal. This is called Foal Heat. The mare will enter estrus 5-12 days post-partum, and enter ovulation 7-15 days post-partum). For an equine breeding facility, this means they can get the mare to produce one foal per year.

Question 34

Describe the cooling mechanisms a stallion uses to maintain spermatogenesis in these conditions

Answer 34

- Counter current heat exchange Pampiniform plexus and testicular artery are in close association which allows for regulation of testicular temperature Cool venous blood absorbs heat from warm arterial blood (ie. arterial blood becomes cool while venous blood is warmed) - Contraction of cremaster muscle promotes venous return and enhances cooling - Relaxation of dartos muscle will increase surface area (smooth scrotum) and lower testes to promote heat loss - Scrotal sweating enables evaporative cooling - External radiant heat loss via the thin, pendulous scrotum Allows for radiation, convection, and conduction of heat away from testes

Question 35

What is the location and function of the ischiocavernosus muscle? a. Surrounds crus of penis, contracts to help maintain erection b. Surrounds bulb of penis, contracts to empty urethra c. Surrounds pelvic urethra, contracts to empty bulbourethral gland d. Surrounds bulbourethral gland, contracts to move seminal plasma

Answer 35

a. Surrounds crus of penis, contracts to help maintain erection

Question 36

Which hormone is most important for driving the recruitment and selection of ovarian follicles? a. Luteinising hormone b. Gonadotropin releasing hormone c. Follicle stimulating hormone d. Estrogen

Answer 36

c. Follicle stimulating hormone

Question 37

What is the order of scrotal and testicular tissues from outside of the body to inside? a. tunica albuginea > tunica dartos > visceral vaginal tunic > parietal vaginal tunic b. visceral vaginal tunic > parietal vaginal tunic > tunica dartos > tunica albuginea c. tunica dartos > visceral vaginal tunic > tunica albuginea > parietal vaginal tunic d. tunica dartos > parietal vaginal tunic > visceral vaginal tunic > tunica albuginea

Answer 37

d. tunica dartos > parietal vaginal tunic > visceral vaginal tunic > tunica albuginea

Question 38

Which of the following occurs immediately prior to the LH peak? a. Progesterone increases, creating negative feedback on the HPG axis b. Estradiol positively feeds back on the surge centre, causing a GnRH surge c. Ovarian prostaglandin E2 and prostaglandin F2α weaken the follicle wall d. The dominant follicle switches from producing progesterone to estrogen

Answer 38

b. Estradiol positively feeds back on the surge centre, causing a GnRH surge

Question 39

Which species has a high concentration of circulating progesterone from many active corpora lutea during the luteal phase? a. Ewe b. Cow c. Mare d. Sow

Answer 39

d. Sow

Question 40

Which is CORRECT in regard to sperm transport in the female tract? a. Sperm form a reservoir in the ampulla, with fertilisation occurring in the isthmus b. Sperm complete capacitation within the uterus, and then bind to the oviductal epithelium prior to fertilisation c. Binding of sperm to the oviductal epithelium prolongs their lifespan d. Capacitation of sperm is completed within minutes of entry into the oviduct

Answer 40

c. Binding of sperm to the oviductal epithelium prolongs their lifespan

Question 41

What is the effect of progesterone on the uterine endometrium? a. Development of uterine glands and histotroph secretion b. Increased contractility and decreased secretory activity c. Release of PGF2α to cause luteolysis d. Epithelium thickening and keratinisation

Answer 41

a. Development of uterine glands and histotroph secretion

Question 42

What is the purpose of the blood-testis barrier? a. To retain high concentrations of testosterone within the testes b. To allow for counter current heat exchange and cool the testes c. To separate Sertoli cells from developing germ cells d. To prevent immune cells from attacking haploid germ cells

Answer 42

d. To prevent immune cells from attacking haploid germ cells

Question 43

What embryonic stage would you find in the ovine uterus 5-6 days after fertilisation? a. Zygote b. Blastocyst c. 8 cell d. Morula

Answer 43

b. Blastocyst

Question 44

What role does oxytocin play in lactation? a. Causes contraction of myoepithelial cells surrounding alveoli to release milk into ducts b. Leads to development of mammary glands late in gestation c. Causes increased pressure in alveoli, drawing circulating products into milk (e.g. water, vitamins) d. Stimulates alveoli to synthesise milk components (e.g. casein, whey, lactose)

Answer 44

a. Causes contraction of myoepithelial cells surrounding alveoli to release milk into ducts

Question 45

Which species has a corpus luteum as the main source of progesterone for all of pregnancy? a. Cow b. Mare c. Bitch d. Ewe

Answer 45

c. Bitch

Question 46

What percentage of singleton neonatal lamb mortality would be considered abnormally high? a. >1% b. >5% c. >10% d. >20%

Answer 46

d. >20%

Question 47

What is a normal sexual behaviour? a. A boar showing teeth grinding and foaming at the mouth, copulating for 15 seconds and ejaculating into the sow’s uterus b. A bull showing the flehmen response and chin resting, copulating for 1-2 minutes and ejaculating into the cow’s cervix c. A tom cat vocalising and showing lordosis, copulating for 2 minutes (first stage) + 45 minutes (second stage) and ejaculating into the queen’s vagina d. A ram pawing and nudging the ewe, copulating for 1-2 seconds and ejaculating in the ewe’s vagina

Answer 47

d. A ram pawing and nudging the ewe, copulating for 1-2 seconds and ejaculating in the ewe’s vagina

Question 48

In which species does multiple gestation commonly lead to fetal loss? a. Bitch b. Mare c. Ewe d. Sow

Answer 48

b. Mare

Question 49

What is CORRECT in relation to ‘foal heat’ in mares? a. Mares ovulate in the first 7-15 days postpartum, but are not able to conceive due to incomplete uterine involution b. Mares ovulate in the first 7-15 days postpartum, but will not conceive if they have a foal nursing due to lactational anestrus c. Mares ovulate and show standing heat in the first 7-15 days postpartum, and can successfully conceive due to rapid uterine involution d. Mares show standing heat in the first 7-15 days postpartum, but do not ovulate at this time and so will not conceive

Answer 49

c. Mares ovulate and show standing heat in the first 7-15 days postpartum, and can successfully conceive due to rapid uterine involution

Question 50

What anatomical structures would be observed on the ovaries of a cow which is pregnant? a. A large corpus luteum and many very small antral follicles b. A corpus albicans and a few small antral follicles c. Multiple corpora lutea and a few medium antral follicles d. A large antral follicle and a regressed corpus luteum

Answer 50

a. A large corpus luteum and many very small antral follicles

Question 51

Which of these clinical observations in the bitch would indicate she is in proestrus? a. Mostly parabasal cells in a vaginal swab, low progesterone (<1ng/mL) b. Attracts dogs but not receptive to mating, red blood cells present in a vaginal swab c. Straw coloured discharge from the vulva, rising progesterone (1-4ngmL) d. A few cornified cells in a vaginal swab, vulva small and dry

Answer 51

b. Attracts dogs but not receptive to mating, red blood cells present in a vaginal swab

Question 52

Where in the efferent duct system would sperm with a proximal cytoplasmic droplet be found? a. Cauda epididymis b. Caput epididymis c. Corpus epididymis d. Vas deferens

Answer 52

b. Caput epididymis

Question 53

Reptiles and birds are able to store semen in specialised crypts for many weeks or months. Where are these crypts found? a. In the infundibulum b. In the cloaca c. In the vagina d. In the uterus

Answer 53

c. In the vagina

Question 54

In birds, how long after ovulation does it take a formed egg to be laid? a. 2 hours b. 6-8 hours c. 12-15 hours d. 23-27 hours

Answer 54

d. 23-27 hours

Question 55

You visit a dairy with 200 cows to perform pregnancy diagnosis and assist with calving. a. Describe the timing and explain the mechanism of maternal recognition of pregnancy in the cow (5 marks)

Answer 55

Pregnancy recognition in the cow occurs ~2 weeks (15-16 days) post fertilisation Conceptus secretes interferon tau (IFNT) → blocks oxytocin receptors in uterine epithelium → blocks producetion of PGF2a → no signal for luteolysis → CL is maintained

Question 56

Describe the cow’s placenta (using a labelled diagram and text), including gross morphology AND describe TWO (2) structures of the placenta that are definitive signs for pregnancy diagnosis by rectal palpation

Answer 56

Cow placenta: epitheliochorial and cotyledonary placenta ● Layers: (6, least invasive) 1. Maternal capillary 2. Endometrial connective tissue 3. Endometrial epithelium 4. Chorionic epithelium 5. Chorionic connective tissue 6. Fetal capillary ● Cotyledonary placenta: - with convex caruncles Definitive signs of pregnancy: Fetal membrane slip Amniotic vesicles Placentomes (fetal cotyledon + maternal caruncle) Fetus

Question 57

Explain the THREE (3) stages of parturition in the cow, including: -TWO (2) clinical signs of impending calving (within 24 hours) -The major positive feedback loop during parturition -TWO (2) indicators of a problem during calving

Answer 57

- Initiation 2-6 hours, up to 24 hours Intiiation of myometrial contractions Cervical dilation Active Labour (delivery of fetus) 0.5-1.5 hours Strong uterine/abdominal contractions Relaxation of pelvic ligaments Mucus production Movement of fetus from uterus to the cervix/vagina Potential problem = dysotcia (if >2 hours of active labour) Delivery of Placenta 6-12 hours Weaker uterine contractions Vasoconstriction at point of placental attachment Movement of remaining placenta from uterus to the cervix/vagina Potential problem = retained membrane (if placenta has not passed in over 12 hours) 24-12 hours before calving: Teats distended/ dribbling Relaxation of leciv ligaments Normal Clinical Signs: Sternal recumbency Straining with contractions during stage 2 Positive Feedback Loop (Ferguson Reflex): Oxytocin produced in paraventricular nucleus of hypothalamus in response to physical pressure on the cervix → drives contractions (spontaneous, autonomic pushing) Indicators of a Problem: No progression >2 hours of active labour Placenta not passed >12 hours post-calving

Question 58

Explain when ram lambs would reach puberty if they were born in April AND why semen quality may be lower in rams in November compared to March

Answer 58

Sheep are short-day breeders, so their peak breeding period would be around March which is when daytime starts to get shorter. Therefore semen quality in November will be lower compared to March, as November has a long daytime as its approaching Summer. Also, the ram lambs would have just reached puberty in November, they may still be at their early stage of sexual maturity, hence a lower semen quality compared to the ones in March, which would have reached their full sexual maturity already. The sperm production will be lowered, meaning lower sperm volume and lower sperm concentration, hence a lower semen quality overall. I think you can mention how melatonin is increasing, causing GnRH to decrease → decrease FSH and LH hence less sperm quantity.

Question 59

Very hot ambient temperatures are predicted for the following month. Describe how the testes are thermoregulated and TWO (2) consequences of increased testicular temperature

Answer 59

Thermoregulation of testes: 1. Countercurrent heat exchange (between testicular artery and pampiniform plexus): warm arterial blood is cooled down by venous blood through passive heat transfer 2. Evaporative heat loss through scrotum sweating + skin relaxation 3. Dartos muscle: can lower testes for cooling and relaxation can increase surface area for heat loss Consequences of increased testicular temperature: 1. Abnormal sperm morphology 2. Decrease sperm motility 3. Damage sperm DNA 4. Complete sperm death at extreme temps

Question 60

One of the rams was recently treated with a Nitrofuran drug for a bacterial infection, at a dose that impacts spermatogenesis by disrupting completion of spermiogenesis. Given this context, answer the following: -Draw a labelled cross section of a seminiferous tubule in this ram’s testes and clearly indicate which cell types would be missing

Answer 60

Mature spermatozoa would be missing. Since drug only affects spermiogenesis, all other cells (spermatogonia, spermatocyte (primary and secondary) and spermatids are still present

Question 61

You visit a commercial piggery which uses artificial insemination to breed grower pigs. a. Describe FIVE (5) physical and/or behavioural changes that occur in pregnant sows when switching from estrogen dominant estrus to progesterone dominant pregnancy

Answer 61

Decreased vocalisation and restlessness No longer standing for boar / not showing interest in boar Vulva softens and becomes paler (no longer red) Increased appetite

Question 62

Describe TWO (2) methods you could use at days 21-30 post insemination to identify a sow that failed to become pregnant from AI. Name THREE (3) key performance indicators of piggery reproductive management efficiency

Answer 62

Methods to identify failed pregnancy: Failure to return to estrus (day 18-24) Ultrasound (day 25+) Transrectal palpation (day 21-60) PregTone device → beeping = no pregnancy KPIs of piggery reproductive management: - Farrowing rate in gilts >85% - Farrowing rate in sows >90% - Pregnancy loss <5% - Lactational anestrus/weaning = 21-28 days - Weaning to estrus/service = 4-6 days - Litter size = 10-13 piglets per sow - Litter born alive = 9-12 piglets per sow - Aiming for 2.25 litters per sow per year

Question 63

-Describe TWO (2) signs of estrus in the sow

Answer 63

- restlessness - mounting other females - male seeking - standing to be mounted

Question 64

Outline the hormonal changes in the estrous cycle of a Bitch (a graph may help) AND outline clinical indicators of each cycle stage

Answer 64

1. Anestrous - 4-5 months ● High FSH ● E2 waves and small peak ● P4 is low ● LH waves ● Clinical indicator: lots of basal & parabasal cells in epithelium, no swollen vagina, no receptive to mating, no roaming 2. Proestrus ● P4 low and E2 increase + peak ● Clinical indicators: red swollen vulva, attract male but not receptive to mating, bloody discharge; cyto: RBCs + intermediate cells and cornified (mostly cornified by late proestrus) 3. Estrus ● peak E2 peak before estrus → decreasing E2, increasing P4 pre-ovulatory P4 specific to bitches -\ ● Clinical indicators: receptive to mating, straw coloured discharge, enlarged vulva, attract and receptive to mating; cyto: mostly cornified and anuclear cells 4. Diestrus ● sustained high P4, low E2 Clinical indicators: ? not receptive to mating, variable discharge, vulva decreases in size, cyto: parabasal cells, neutrophils

Question 65

Name THREE (3) methods for artificial insemination in the Bitch AND explain which method(s) would produce the highest pregnancy rates with frozen semen

Answer 65

Deep vaginal insemination o Catheter inserted into cranial vagina o Used for fresh and chilled semen Transcervical (intrauterine) insemination o Endoscope used to visualise cervix, catheter passed through into uterus o Used for fresh, chilled or frozen semen * Laparotomy (surgical) insemination o Midline laparotomy to expose uterus, catheter inserted into lumen of each horn – requires anaesthesia o Used for fresh, chilled or frozen semen which is best? Laparotomy would produce the highest pregnancy rates for FROZEN semen as semen is placed directly into the uterine horn

Question 66

-Explain the different phases of sperm transport post-insemination

Answer 66

Rapid Minutes after mating Sperm pumped along female tract due to contractions of uterine smooth muscle These sperm are unlikely to fertilize as they arrive too early (oocyte not ready yet) Sustained Hours (or days) after mating Trickle entry of sperm through the UTJ These sperm have a chance to fertilize

Question 67

-Describe the various barriers to sperm in the female tract

Answer 67

1. Retrograde flow - Dependent on viscosity, site of deposition, and copulatory plug (bulbus glandis) 2. Phagocytosis by neutrophils of female immune system - sperm/extenders elicit immune response 3. Physical barriers a. UTJ and cervix

Question 68

Explain the ideal time during the estrous cycle to inseminate a Bitch

Answer 68

Inseminate 2-3 days after ovulation Ovulation 3 days after start of estrus (LH surge) When P4 >10ng/ml = ovulation has occurred Immature oocytes ovulated takes 2-3 days to mature before it can be fertilised Sperm requires 3 hours for capacitation in the isthmus, but can survive in the female reproductive tract for 72 hours. Bitch estrus cycle = 9 days Ovulation occurs ~3 days after the onset of estrus BUT fertilisation occurs ~5-6 days after the onset of estrus → inseminate ~5-6 days after the start of estrus