Week 2

Question 1

Causes of Anoestrus

True anoestrus vs. apparent anoestrus

Answer 1

* lactation (cattle), season, presence of offspring, stress, pathology, pregnancy

* True anoestrus: caused by insufficient hormonal stimuli

* Apparent anoestrus: failure to detect oestrus

Question 2

What is an example of a long-day breeder? Short-day breeder? What is the onset of seasonal oestrus determined by?

Answer 2

* Long-day breeders: mares

* short- day breeders: small ruminants

* onest of seasonal oestrus determined by photoperiod mainly and secondarily temperature

Question 3

short-day breeder vs. long-day breeder stimulation of oestrus

Answer 3

Short day breeder: high levels of melatonin stimulate GnRH release (small ruminants)

* Long-day breeder: low levels of melatonin stimulate GnRH release (mare)

Question 4

What is the mechanism of action during long photoperiods to cause GnRH or inhibit release (depending on whether short or long day breeders)?

Answer 4

* Long photoperiods–> sensory neurons in the retina stimulate excitatory neurons–> stimulate inhibitor neurons in the pineal gland to release inhibitory neurotransmitters–> preventing pinealovytes from synthesizing and releasing large quantities of melatonin__. low melatonin levels–> increase in RF-amide related peptide 3–> in long day breeders this results in increased kisspeptin secretion–> acts on GnRH neurons via GPCR–> short day breeders high RFRP-3 inhibits kisspeptin and therefore inhibits GnRH release

* During short photoperiods–> excitatory pathways are less active–> decreased inhibition of pinealocytes–> melatonin release

Question 5

How long are ruminants and pigs oestrus cycles?

Answer 5

21 days

Question 6

Duration of oestrus (standing heat) and the time of ovulation for cattle, sheep, goat, pig?

Answer 6

* Cattle- duration of oestrus 18 hours- time of ovulation 10-11 hours after end of oestrus

* Sheep- duration of oestrus 24-36 hours- time of ovulation 24-30 hours after beginning of oestrus

* Goat- duration of oestrus 32-40 hours- time of ovulation 30-36 hours after beginning of oestrus

* Pig- duration of oestrus 2-3 days- time of ovulation 35- 45 hours after beginning of oestrus

Question 7

How long is the horse oestrus cycle? Standing heat? ovulation?

Answer 7

* Horses have on average 21 day oestrus cycles

* Standing heat up to a week (4-8 days)

* Ovulation happens 1-2 days before the end of oestrus (horse will still be in heat for 1-2 days after ovulation, so it is possible to waste semen- she may still be responsive to stallion after)

Question 8

Follicular dynamics in monotocuous vs. polytocuous species?

Answer 8

* generally only one follicle is reaching dominance in non-litter bearers. The largest follicle around at the time of dropping progesterone levels will reach dominance and secrete inhibin, which has a negative feedback on FSH release from the pituitary. The larger the follicle, the less dependent it is on FSH. Additionally, the blood supply to the other follicles is reduced so that the biggest follicle is gettings the most blood and tehrefore, the largest amount of FSH (anything left will go to the large follicle).

* In litter- bearers on the other hand, not one follicle grows up but rather a cohort of follicles. Multiple follicles (up to 10) are needed to generate enough inhibin in order to exert the negative feedback on the pituitary.

Question 9

Size of antral follicles in most species and then in the horse

Answer 9

* small follicles: < 3 mm (horse < 10 mm)

medium follicles: 4-6 mm (horse 10-20 mm)

* large follicles: > 6 mm (horse > 20 mm)

Question 10

How does a bitch’s oestrus cycle differ?

Answer 10

* one oestrus cycle every 7 months on average

* Endocrinologically, the LH surge marks the beginning of oestrus (day 0)

* LH surge lasts for 24 to 48 hours

* plasma progesterone levels begin to increase slowly in late prooestrus but suddenly double at the time of LH surge– therefore progesterone levels are a valuable tool to indirectly determine LH surge

* Prooestrus: 9 days (on average 0-27 day range)– VERY LONG COMPARED TO OTHER SPECIES– will see blood, how you know they are in proestrus. Blood from the uterus- not like humans- it’s because the uterus is hyperaemic and the vessels became leaky therefore diapedisis of erythrocytes (the further into oestrus- end up with straw coloured fluid coming out)

* Oestrus: 8 days based on LH peak and first day of dioestrus, 9 days based on behavioural signs, range: 4-24 days)

* Dioestrus: average- 57 days in the pregnant bitch, dioestrus is slightly longer in the non-pregnant bitch)

Question 11

What hormone level in a bitch is similar to pregnant or non-pregnant animals?

Answer 11

Progesterone

Question 12

When does ovulation occur? What is unique about canine oocytes?

Answer 12

* Ovulation occurs approximately two days after the LH peak and is not dependent on breeding

* Canine oocytes are ovulated as primary oocytes and need to go through a phase of maturation before they can be fertilized. It takes 48 to 72 hours for them to undergo meiotic division to become secondary oocytes

Question 13

What is unique about cat ovulation? oestrus cycle?

Answer 13

* Cats need to mate multiple times in order to ovulate

* Cats are seasonaly polyoestrus–> interoestrous interval is 2 to 3 weeks in spring, summer, and autumn followed by a time of anoestrus in winter (can become non seasonal breeders if indoor cats with much artificial light)

** Prooestrus: 1.2 days average

* Oestrus: 7.2 days average (3-26 days range)

* postoestrus: 8-10 days; range 0-20 days (follows oestrus if ovulation does not occur…. apparent quiescence of ovaries, followed by prep of next follicular growth for next oestrus

* Dioestrus: average duration 40 days in the pseudopregnant, 60 days in the pregnant queen… follows oestrus if ovulation does occur; progesterone dominate luteal phase; ovulation without fertilization: CL develop and produce progesterone for up to 45 days… clinical signs do not occur except for a long period without oestrus signs. Ovulation WITH fertilization: ova remain fertilizable for up to 24 hours post ovulation; sperm requires 2 to 24 hours after ejaculation for capacitation and remains viable for 50 hours after ejaculation

Question 14

What is silent heat?

Answer 14

The term we, as humans, use to describe our own short comings when it comes to oestrus detection

Question 15

What signs do you look for in cattle to detect oestrus? What is a problem with detection?

Answer 15

* Prooestrus/ early oestrus: cows riding other cows, restlessness, vocalization.

* oestrus: standing to be mounted; presence of ruffled hair at base of tail; rubbed off tail paint (if used)

* The problem is that 70% of cows show heat between 6pm and 6am (most inconvenient). Therefore, tail paint or heat detection devices (e.g. Kamar) are used to assess if cows have been mounted. Could also use pedometers.

Question 16

When should mares be teased? When is teasing not advised?

Answer 16

Teased daily from 3 days post-partum until 60 day pregnant

* Stallion in a wagon and the mares that follow

* caution used with fencing due to potential of broken legs or a dominant mare/ shy mare though the shy one is in heat

* if with foal, teasing may not be the best thing to use, in this case ultrasound

Question 17

How can you tell if a canine is in oestrus?

Answer 17

* Breeding reflexes

* vaginal exam- speculum

* exfoliative cytology

* serum progesterone levels

Question 18

What are the two basic mechanisms of synchronization of oestrus?

Answer 18

* Inducing luteolysis e.g. PGF2alpha (only works on CLs older than 5 days– also a single dose of PGF2alpha is a potent abortifacient in most domestic species)— administer 2 doses in ruminants 11 days apart and 14 days apart in horses

* prolonging luteal phase e.g. progesterone

Question 19

What are the benefits to synchronization of oestrus in large species? What is the prerequisite for synchronization of oestrus?

Answer 19

1. Improved oestrus detection rate
2. Allows time mating and AI in females in which oestrus detection is difficult
3. More efficient use of AI with fresh or frozen semen in groups of animals
4. Synchronization of oestrus and ovulation for embryo transfer

** prerequisite is ACTIVE OVARIES

Question 20

Why is synchronization often not very tight in horses?

Answer 20

* It is dependent on the biggest follicle present on her ovary at the time e.g. a mare with a 35 mm follicle at the time of treatment will come into heat much quicker than a mare that only has small or atretic follicles

Question 21

What is the advantage of using progesterone for synchronization? Disadvantages? Most commonly used devices?

Answer 21

Animals do not have a CL at the time of treatment, disadvantage: long time interval between time of treatment and mating/ insemination

** most commonly used in ruminants– controlled intravaginal drug release (CIDR) or progesterone impregnanted intravaginal device (PRID)

* horses- injected or orally

* pigs- orally

** length of tx can vary but is usually 7-10 days in ruminants and 10-14 days in horses; often 14-18 days in pigs

Question 22

When do you administer PGF2alpha in a cow?

Answer 22

1st dose anytime, then 14 days after 1st dose the 2nd. Between day 6 to day 17 of oestrous cycle

Question 23

When is human chorionic gonadtropins (hcG) used? Other option?

Answer 23

* LH like function– if give at the right time with 35 mm follicle, some oedema, 85% of mares ovulate between 36 and 42 hours– might not work in transition when lack of LH receptors

* GnRH analogue is another option will ovulate between 42-48 hours if given as soon as largest follicle is 35 mm (more expensive than hCG)– implant should be removed to prevent downregulation- commonly placed in mucosa of labia

Question 24

What do you do if you want to join ewes outside of breeding season (spring/summer)?

Answer 24

* Ram effect or Whitten effect (more pronounced in british breeds than merinos)– only effective if before the summer solstice (longest day)

* stimulate oestrus to concentrate joining by using ram phermones– 1st keep them at least 1km away (even neighboring properties) from the ewes for at least one month before the start of joining… the sudden introduction of rams to ewes will induce ewes to start cycling within 17 to 25 days after first ram or teaser introduction

* if AI is going to be used- teasers (vasectomised) rams can be used instead of intact rams- they have the same effect– can use a marking harness to mark ewes in oestrus

Question 25

How else can you manipulate oestrus in small ruminants and horses?

Answer 25

\* Small ruminants can be kept inside to simulate shorter days or melatonin implants \* IN mares the use of artificiallly extended day length-- 16 hour light regimen from about the 1st of June-- 2 month advantage in the onset of first ovulation of the season.

Question 26

Major steps of AI

Answer 26

1. Collection of semen from teh male 2. Preservation and extension of sperm 3. Insemination of the female

Question 27

Why is a semen extender used? What are the components of frozen semen extenders?

Answer 27

To protect sperm against possible damage by toxic seminal plasma. Provide nutrients and cooling buffers if the semen is to be cooled. If the semen is to be frozen, penetrating cryoprotectants have to be added e.g. glycerol, DMSO (egg yolk is a common component of frozen semen extenders)

Question 28

Why use semen extenders? What is in it?

Answer 28

\* ejaculate can be split into multiple doses \* increase longevity of sperm outside of the repro tract \* allows shipping of semen (overnight if fresh chilled, for any amount if frozen) \*\* buffer (tris, citrate), energy in form of sugar (sucrose, lactose, glucose), antibiotics (ticarcillin, amikacin, penicillin)

Question 29

What are the site of AI for cattle, horse, sheep, pig, dog? What is the benefit of depositing in a location closer to the sperm desintation.

Answer 29

The number of sperm per AI can be greatly reduced. e.g. up to 100 AI doses can be gained from a single bovine ejaculate. 10 doses from a single stallion ejaculate

Question 30

Fresh vs. frozen semen

Answer 30

Fresh extended semen, even if chilled, has a life span of about 2 days for horses and 7 days for pigs. Good pregnancy rates are avhieved if mares are inseminated within 48 hours before ovulation or 6 hours after ovulation. \* frozen can be stored in liquid nitrogen without loss of fertility for generations. The biggest disadvantage is once it is thawed it is only good for a short time-- AI has to be much better timed!! Frozen semen-- from 12 hours before ovulation to 6 hours after ovulation (the 6 hours after determined by the deteriorating oocyte after that time).

Question 31

What is ART?

Answer 31

Assisted Reproductive Technologies. Currently used in cattle, sheep, goats, pigs, and with more difficulty in dogs and horses. To produce offspring from subfertile males or females, increase the number of offspring from selected mature or juvenile females, to salvage sperm or oocytes from dead or dying animals, endangered species \* Sperm sexing- separation of X and Y bearing spermatozoa by flow cytometry (X bearing sperm have more DNA, therefore they take up more dye-- emit more light-- therefore sperm is directed to one side or the other)

Question 32

What is Classic IVF? ICSI? GIFT? Embryo splitting? SCNT?

Answer 32

Egg and sperm are incubated together in a small petri dish ICSI: eggs are collected and one sperm injected into one egg GIFT: egg and sperm are transffered into uterine tube (e.g. donor egg from older mare with uterine pathologies to young mare) Embryo splitting: early embryos can be split to derive identical offspring (best done at 6 to 8 cell stage) SCNT: also known as cloning; a nucleus from a donor adult cell (somatic cell) is transferred to an egg that has been enucleated. If the egg begins to divide normally it is transferred into the uterus of the surrogate mother

Question 33

What is embryo transfer?

Answer 33

Allows a dam to have many more offspring in a given year--\> propagation of genetically valuable individuals. Widely used in cattle practice- considered routine. ET has a much smaller genetic impact than sire selection. \*\* principle of ET is: Superovulate dam (exogenous FSH)--\> dam is inseminated at appropriate time--\> embryo flush is performed 6 to 8 days later--\> embryos are then either transferred into a synchronized recipient or frozen for future use--\> in small ruminants the ET process is usually done laparascopy or laparotomy-- in cattle and horses it is done transvaginally

Question 34

Answer 34

Question 35

Answer 35

Question 36

Which arteries and what tissue is engorged during erection? What else happens?

Answer 36

\* stimulation--\> walls of coiled (helicine) aa. of deep a. or penis and bulb relax \* lumina open--\> increase blood flow in cavernous tissue \* venous drainage inadequate--\> increase BP in erectile tissue--\> compression of veins \* additional blood pumped in by contraction of ischiocavernosus and bulbospongiosus

Question 37

Why does coitus in a dog result in dogs being tied together?

Answer 37

\* Bulbus glandis remains engorged after the "turn" \* contraction of the muscle at the base of the penis prevent venous outflow from the bulbis glandis \* also the sphincter mm. of the vulva constrict, compressing the dorsal veins of the penis, preventing blood from leaving

Question 38

BG?

Answer 38

Bulbis Glandis

Question 39

What stimulates glans penis before coitus? What muscles do AP travel to?

Answer 39

Temperature and pressure \* urethralis muscle, bulbospongiosus muscle, ischiocavernosus muscle

Question 40

What are the functions of the epididymis?

Answer 40

\* Water absorption \* Spermatozoal transport \* Blood-epididymis barrier \*spermatozoal maturation (acquisition of motility)- structural changes, physiological changes

Question 41

Where do sperm gain motility?

Answer 41

Distal corpus-- translocation of cytoplasmic droplet within the distal corpus and shedding of the droplet within the cauda epidiymis or upon ejaculation. And other more subtle changes including alternations in sperm metabolism

Question 42

What happens when sperm enters the female?

Answer 42

Either retrograde loss (gravity is against the sperm), phagocytosis (sperm has to try to avoid neutrophils), entrance into cervix/uterus \*\* with the introduction of semen there is always also an introduction of microorganisms which originate from teh male or the female (caudal vagina). From about 3 hours of semen deposition a marked neutrophil reaction occurs-- attack microorganisms and sperm. They can phagocytose live and dead sperm, multiple sperm at once.

Question 44

Why can PMIE occur after mating?

Answer 44

Very quickly after insemination there is a marked increase in neutrophil numbers into the uterus. this a normal inflammatory reaction usually resolves within 48 hours. If it does not, it leads to post-mating induced endometritis (PMIE)- which is very common in mares

Question 45

What are the barriers to sperm reaching the target?

Answer 45

1. Immediate transport- retrograde loss (gravity against them), phagocytosis 2. (if semen is deposited into the vagina like in dogs and cats) Cervix- "privleged pathways" are in the crypts (away from the sulfomucins- mucous is not as sticky and flows in the right direction), removal of non-motile sperm, removal of some abnormalities 3. Uterus - capacitation initiated (decapacitated sperm are not fertile), phagocytosis 4. Oviduct- capacitation completed, hyperactive motility 5. Fertilization- acrosome reaction, spermatozoon penetrates oocyte, male and female pronuclei form

Question 46

What is the "privileged pathway?"

Answer 46

\*\* selecting for motile sperm Oestrogen leads to the production of sulfomucins from the apical portion of the cervical mucosa. The secretion of this viscous substance is directed towards the lumen and it is flowing into a caudal direction. Sperm, which get into it, are flushed out and won't make it into the uterus. \* A less viscous substance, sialomucin, is produced in the cervical crypts and facilitates an easier transport route for the sperm (privileged pathway)-- However, the sperm have to actively swim through the mucus. It is therefore proposed that this is a mechanism to select for progressively motile sperm.

Question 47

What is the difference between epididymal, ejaculated, capacitated sperm?

Answer 47

\* Epididymal spermatozoa- (deposited in the epididymis on the spermatozoa) the plasma membrane of epididymal spermatozoa contains a complement of surface molecules (carbohydrates and proteins) \* Ejaculated- ejaculated sperm get in contact with seminal plasma, these surface molecules get coated by seminal plasma proteins. \* Capactitated (in the uterine tube)= hypermotility (break dancing to increase chance at coming into contact with the egg) When sperm are exposed to the female tract environment the seminal plasma molecules are removed. They then expose portions of molecules, which are able to bind the zona pellucida. It is important to note that capacitated sperm can become decapacitated if incubated in the appropriate media (e.g. seminal plasma)

Question 48

What two ways do the sperm travel to the oviduct?

Answer 48

Rapid and sustained transport-- rapid transport via uterine contractions by the dam's oestradiol and prostaglandins in the semen (PGF2alph and PGE1). And slow transport-- that come from reservoirs in the cervix and teh uterotubal junction (UTJ)

Question 49

What is meant by hyperactive motility?

Answer 49

\* once sperm reaches the uterine tube, their motility pattern changes and they become hyperactive. IN the ampulla of the uterine tube, the pattern changes from straight line (progressive motility) to not linear, a random-looking dancing motion (hyperactive motility). It is believe that the epithelium produces proteins that bring about those changes.

Question 50

What regions unit with the sperm and the oocyte? What happens as a consequence?

Answer 50

Sperm's zona binding region (ZBR) reactst with Zona Pellucida Protein 3 (ZP3)-- causing physical attachment of the sperm. As a consequence the acrosome reaction is initiated.

Question 51

What is the acrosomal reaction? What happens after?

Answer 51

\* has to happen before the sperm penetrates the egg \*\* the plasma membrane fuses with the OUTER acrosomal membrane--\> opens channels--\> acrosomal contents which are enzymes can find their way out and eat a hole into the zona pellucida (gets penetrated by enzymes) During the acrosomal reaction, the membrane overlying the acrosomal membrane begins to fuse with the outer acrosomal membrane. This leads to vesiculation and pore formation, so that the acrosomal contents can reach the zona pellucida and facilitate the sperm's penetration through it. There are special binding proteins. \*\* after the vesicles slough and the inner acrosomal membrane and the post- nuclear cap are left behind

Question 52

What is the cortical block?

Answer 52

When the sperm is in the perivitelline space near the cortical granules, the cortical block is initiated- which is critical to prevent polyspermy (more than one sperm fertilizing an egg). Once the cortical granules are released into the perivitelline space, they bring about a biochemical change in the zona pellucida that makes it imprenetrable for other sperm.

Question 53

What happens after fusion?

Answer 53

the sperm's nuclear membrane disappears and the nucleus decondenses and the male pronucleus is formed. The male pronucleus subsequently fuses with the female pronucleus. this event is called syngamy and marks successful fertilization. Embryongenesis can proceed.

Question 54

What are the steps from hyperactive motility (in the uterine tube) to syngamy?

Answer 54

Question 55

What happens to the ovum (aka blastodisc, blastoderm, germ disc) in the female bird after release from the follicle on the ovary?

Answer 55

The yolk (which carries the ovum) is produced by the ovary initially. After release from the follicle on the ovary, the yolk moves into the oviduct where it is fertilized and has added to it the albumen, shell membranes, and shell.

Question 56

What leads from the testes to the cloaca in the bird? Where are the testes located? WHat is unique about their size?

Answer 56

Deferent duct Testes are located against the backbone at the front of the kidney. Left testi is often larger than the right

Question 57

In birds, what is the penis?

Answer 57

Deferent duct enters a small pimple like structure in the cloaca that is the penis in a bird.

Question 58

In the bird, what happens in the seminiferous tubules?

Answer 58

In the testes, the twisted tubes called the seminiferous tubules are found. Meiosis and transformation produces the sperm.

Question 59

What produces androgens in birds and what do they control?

Answer 59

\* Testes produce hormones called androgens that influence the development of secondary sex characterisitcs such as comb growth and condition, male behaviour and mating

Question 60

How many ovaries in a mature bird? Where ?

Answer 60

Female embryo chicken has two sets of ovaries, one of these survives and reaches maturity to produce eggs. It is located in the laying hen just in front of the kidneys in the abdominal cavity and is firmly attached to the wall of the cavity. The ovary is well endowed with blood vessels to ensure there is no hindrance to the transport of nutrients to the developing yolk.

Question 61

What actually is a matured egg yolk? How long does it take to develop? What is the place called where the follicle splits to release the yolk into the oviduct?

Answer 61

Follicle 10 days to develop Stigma- the place where the follicle normally splits to release the yolk into the oviduct (blood spot appears in the yolk if it splits at any other place)

Question 62

What are the five stages of development in the active ovary?

Answer 62

1. Primary follicles- follicles that have not yet commenced to grow 2. Growing follicles 3. Mature follicles- ready for release 4. Discharged follicles- where the yolk has been released 5. Atretic follicles- those from which the yolk has been released some time ago

Question 63

What is the function of the oviduct?

Answer 63

Produce the albumen, shell membranes, and shell around the yolk to complete the egg. A long tube well supplied with blood. Glands that produce the albumen, shell membranes and shell.

Question 64

What are the 5 parts of the oviduct in the bird?

Answer 64

1. Infundibulum: collects yolk after release directing it to the oviduct (fertilization of the ovum by the male sperm occurs here) 2. Ampulla or magnum: secretes 40% of albumen 3. Isthmus: secretes some albumen and shell membranes 4. Uterus or shell gland: secretes 40% of albumen and the egg's shell 5. Vagina: secretes the eggs outer cuticle and possibly the shell pigment

Question 65

What does androgen do in the female bird? Oestrogen? Progesterone?

Answer 65

\* Androgen- comb growth and condition, formation of albumen \* Oestrogen: growth of female plumage (red color when ready to produce eggs), mating and nesting behaviour, oviduct development together with the nutrient supply to the ovary/ oviduct for egg formation \* Progesterone: with androgen is involved in the production of albumen and the carriage of the message to the pituitary gland to release LH

Question 66

What are the main parts of an egg? Where are they produced?

Answer 66

1. Yolk carrying the ovum- produced by the ovary 2. Albumen or white- produced mainly in the magnum 3. Shell membranes- produced in the isthmus 4. Shell- produced in the uterus or shell gland

Question 67

What attaches the ovary to the abdominal cavity in the bird?

Answer 67

Meso-ovarian ligament

Question 68

Major components of yolk

Answer 68

Question 69

What initiates yolk development in the maturing pullet? How do compounds for yolk material get to the target follicle?

Answer 69

FSH. \* compounds in the yolk material are formed in the liver and transported by the blood steram to the target follicle into the yolk (signal from oestrogen, progesterone, and testosterone after FSH)

Question 70

What makes up the concentric rings of darker and ligher coloured material of the yolk? What is the name of the membrane that contains the yolk?

Answer 70

xanthophylls vitellin membrane

Question 71

What is ovulation in the bird? What causes ovulation?

Answer 71

Release of the yolk \* a mature yolk in the follicle causes LH release--\> causes the follicle containing the mature yolk to split along the stigma releasing it into the oviduct abdominal cavity

Question 72

When does a hen reach sexual maturity? What factors impact this? How fast can another yolk be released after an egg has been lain?

Answer 72

Reached when the hen lays the first egg. 18-24 weeks. Can be manipulated by controlled feeding practices, light intensity and day length management. \*\* 40- 60 minutes after the previous egg has been laid-- a subsequent yolk can be released

Question 73

What are clutches?

Answer 73

Eggs laid on successive days are called a cluth. Clutches are separated by days when no eggs are laid. \* very individual- 2 up to 100 eggs. Normal is about 3-8 eggs.

Question 74

Egg formation time?

Answer 74

23-26 hours. If more than 24 hours, ovulation is missed, and the start of the new cluth will be earlier in the next laying day. \*\* hens that produce long clutches release the yolk very shortly after first light (natural or artificial)

Question 75

When is peak ovulation in a bird?

Answer 75

3-5 weeks after first egg lay

Question 76

How long is the oviduct?

Answer 76

70 centimers

Question 77

What are the four types of albumen in a normal egg?

Answer 77

Chalazae- two twisted cords holds yolk in position Liquid albumen- as yolk moves along the oviduct water is added Dense layers- mucin.... rotation of developing egg causes albumen to separate into different layers the inner liquid and dense layers \* outer liquid layer- caused by addition of more water when in the uterus

Question 78

Where does the shell form in the bird?

Answer 78

\* isthmus of the oviduct... lays down the first layer: crystals of calcium carbonate. (75 minutes \* uterus (18-20 hours)- 40% of albumen and most of the shell is added

Question 79

What are the two layers of the shell?

Answer 79

1. Mammillary layer: a sponge like layer composed of soft calcite crystals (CaCO3). Inner layer 2. Palisade layer: formed of columns of hard calcite crystals- the longer the columns the stronger the shell. Outer layer.

Question 80

Where does the calcium for the eggshell come from? How much calcium is used per egg and per day? What other minerals does the egg shell contain? What can cause thin shells?

Answer 80

Diet, special bone called the medullary bone, skeleton 2.5 grams per egg (2.0 g/ day) \*\* shell also contains small quantities of sodium, potassium and magnesium \*\* hot weather can cause decreased carbonate and thin shelled eggs because of the increase in respiratory rate removing CO2 from teh blood

Question 81

What are 7 factors that influence egg shell quality?

Answer 81

1. Length of time in lay- longer in lay, the weaker the shells become (can't get enough calcium- better layers deplete their skeleton) 2. Increased environmental temperature- less food consumption and more CO2 out 3. Egg laying time- early morning will have thinner shells because the bird does not eat at night 4. Stress (thinner) 5. Body checked and misshapen eggs: birds startled after egg has entered the uterus-- more shell is laid afterward but over the misshapen first part 6. Disease e.g. infectious bronchitis cause weak shell and misshapen eggs 7. Drugs

Question 82

Why does an egg have pores?

Answer 82

\* 8000 pores in the shell of a normal egg \* function is to provide for the gaseous exchange during incubation and embryonic development \* developing embryo requires oxygen and gives off CO2 \* when the egg is first laid most of the pores are closed \* as it ages, more open up \* during the laying process the cuticle acts as a lubricant, but dries to initially close off the pores as a barrier to fungi and bacteria

Question 83

Why is the female reproduction system of a bird so unique?

Answer 83

Enables the bird to reproduce but still fly

Question 84

How long is a chick's incubation period?

Answer 84

3 weeks (the egg contains everything the chick needs)

Question 85

What gives yolk the bright orange?

Answer 85

Carotenoids. Usually synthetic these days. Real comes from marigolds or red capiscums

Question 86

What is albumen?

Answer 86

Mainly proteins- ovalbumin, ovotransferrin, ovomucoid, ovoglobulin, lysozyme and ovomucin... Function is to protein the embryo (or yolk) from attack by microorganisms and serve as a source of water, protein and minerals for the embryo

Question 87

What is the conceptus?

Answer 87

\* everything that develops from the zygote- embryo/fetus, extra-embryonic membranes (amnion, allantois, chorion, yolk sac)

Question 88

What is an embryo? What is the definition of fetus?

Answer 88

Embryo: early stages of development (blastulation, gastrulation, and organogenesis-- usually not identifiable as a member of a species). \*\* fetus: More advanced form of an embryo. When the organs start developing. Can be recognized as a member of the species. Fetal stage ends with expulsion from the uterus--\> neonate

Question 89

What are the stages of development within the mother?

Answer 89

1. Development within the zona pellucida 2. Hatching of the blastocyst 3. Formation of the extraembryonic membranes 4. Maternal recognition of pregnancy

Question 90

What are the 5 stages of development within the zona pellucida?

Answer 90

1. Ootid- large amount of cytoplasm present, no more will be generated, only partitioned in embryonic cleavage. Stage when male and female pronuclei are present in the oocyte. 2. Zygote- once pronuclei fuse, the oocyte is called a zygote 3. 2-celled embryo: First cleavage generates a 2 cell embryo whose cells are called blastomeres. Each blastomere undergoes divisions to an 8 cell embryo- totipotent. Identical twins form if a 2-cell embryo splits and each blastomere develops independently 4. Morula- when more than 16 cells are formed and it becomes difficult to count them. (mulberry in latin) 5. Early blastocyst: when the morula forms, the outer cells tend to become compacted more than the inner cells. Two distinct cell populations form: the outer and the inner cells. The inner cells develop gap junctions, which facilitate cell to cell communication and the outer cells develop tight junctions. Sodium pump brings sodium and water inside the embryo-- forming a cavity called the BLASTOCOEL. Once a distinct cavity is visible- the embryo is called a BLASTOCYST. The inner cells will form the inner cell mass (ICM), which gives rise to the embryo proper and the outer cells form trophoblast cells-- which will give rise to the CHORION (fetal part of the placenta)

Question 92

What happens with the hatching of the blastocyst?

Answer 92

As the cells under mitoses- the fluid inside the cavity is increasing the pressure within the zona pellucida. Outer trophoblast cells are producing proteolytic enzymes, which weaken the zona pellucida. Finally the blastocyst contracts and relaxes, causing pressure pulses, which lead to the rupture of the zona pellucida. Once freed the embryo undergoes rapid growth.

Question 93

Location of embryo pre attachment phase

Answer 93

Question 94

What happens during the formation of the extraembryonic membranes?

Answer 94

1. In the blastocyst, a thin lining will form beneath the inner cell mass and grow around the blastocyst cavity. that is the endoderm (blue) The mesoderm will form inbetween the embryo and the endoderm (red). 2. Once the endoderm finishes its growth it has formed the yolk sac. the mesoderm grows outwards. 3. The mesoderm keeps growing and pushes against the trophectoderm (previously called trophoblast cells). this leads to the formation of little "wings" around the embryo, called amniotic folds. The mesoderm now completely surrounds the yolk sac and the amniotic folds continue growing upwards around the embryo. 4. The allantois forms as an outgrowth from the embryonic hindgut. The yolk sac and the developing allantois are now completely surrounded by the mesoderm. The mesoderm fuses with the cells of the trophectoderm to form the chorion. 5. The amniotic folds join above the embryo, forming the amniotic cavity right around the embryo. The chorion now completely surrounds the entire conceptus. The yolk sac is beginning to regress. It is not truly filled with yolk. 6. 2 sacs are enveloping the embyro (amnion and chorion). Both are formed by the trophectoderm and mesoderm. The allantois continues to expand and will fuse with the chorion to form the allantochorion/ chorioallantois.

Question 95

What happens during maternal recognition of pregnancy?

Answer 95

Question 96

Answer 96

Bovine conceptus. Embryo is visible inside its amnion (clear bubble).

Question 97

How does the ruminant method of maternal recognition vary?

Answer 97

\* Luteolysis is induced by countercurrent mechanism as discussed earlier--\> PGF2alpha from UO- vein transferred into ovarian artry. \* in pregnancy PGF2alpha has to be prevented!!-- the blastocyst secretes interferon-tau (ovine and bovine)-- which binds to the endometrium and prevents oxytocin receptor synthesis (critical in the process of luteolysis-- preventing oxytocin receptor synthesis prevents PGF2alpha production) \* interferon-tau also stimulate uterine gland secretion providing embryonic support. It is NOT luteotropic (it does not act on the CL) \* pregnancy needs to establish ipsilateral to the CL for this to work. Otherwise PGF2alpha will be produced from the horn closest to the CL and the CL will be lost.

Question 98

What happens with no conceptus present and with conceptus present in ruminants?

Answer 98

\* No conceptus present: luteolysis around day 15/16, the cow will return to oestrus within a few days \*Conceptus present and maternal recognition of pregnancy was successful: progesterone stays elevated because luteolysis does not occur. Oxytocin receptor expression is blocked by interferon gamma and therefore no PGF2alpha is not sufficient to induce luteolysis

Question 99

What is the porcine method of maternal recognition?

Answer 99

\* pig differs from ruminants as even pregnant animals, PGF2alpha is produced, but it does not reach the ovary \* non-pregnant sow: oxytocin (from endometrium, CLs, and pituitary) is produced and promotes PGF2alpha production by the endometrium. PGF2alpha diffuses to the capillaries and is drained to the uterine vein. From there it is transported to ovaries and causes luteolysis. \* pregnant sow: the blastocysts produce oestradiol that causes PGF2alpha to be rerouted into the endometrium. So instead of reaching the blood vessels in the endometrium and therefore the CLs, it is instead "dumped" into the lumen of the endometrium. In order for this to occur, at least 2 blastocysts have to be present in each horn (4 conceptuses total). If there is less than this number, not enough oestradiol is produced by the conceptuses and luteolysis consequently occurs

Question 100

What is the equine method of maternal recognition?

Answer 100

The blastocyst does not elongate like the sow and cow (no massive growth, which is needed in the cow and sow for either the oestrodial or interferon-tau reaches the CL-- sow you need 2 embryos on each side to produce enough oestrodial, cow embryo needs to be ipsilateral so interferon-tau reaches the right side of the PGF2alpha production), but instead stays in a spherical shape. In order to make contact with the endometrium and prevent PGF2alpha production, the conceptus has to migrate all over the endometrial surface. Between days 12 and 14 after ovulation it needs to make contact with every cm of the endometrium 12 to 14 times a day. If that does not happen, PGF2alpha is produced and luteolysis occurs. \* the embryo is surrounded by tough glycoprotein capsule, which keeps it in a spherical shape. This capsule is only lost around day 16/17. that is when the shape of the embryo becomes less regular.

Question 101

What is the canine "method" of maternal recognition?

Answer 101

The progesterone profile in pregnant and non-pregnant animals is very similar. Every bitch goes either through pregnancy or pseudopregnancy after ovulation. Therefore it is believed that no maternal recognition of pregnancy is present in the bitch. \* the only real difference is the pronounced drop which causes parturition to begin \* important part is the CL stays anyway

Question 102

What does oestrodial lead to in large doses?

Answer 102

LH surge

Question 103

Seasonal anoestrus in house cats vs. feral cats

Answer 103

Cats under artificial lighting may come in heat anytime of the year, while house cats under intermittent light have unpredictable heat cycles. Feral cats- Throughout the breeding season, queens go into and out of heat several times but not always at regular intervals. They may exhibit continuous heat cycles in early spring (averaging 14 to 21 days from the beginning of one cycle to the beginning of the next), followed in late spring by cycles that are further apart. Each queen establishes her own normal rhythm.

Question 104

What is the key mechanism that affect short-day and long-day breeders in very different ways?

Answer 104

Melatonin- stimulated by kisspeptin secretion. In short-day breeder: high melatonin, stimulates GnRH release, but in long-day breeders LOW levels of melatonin stimulate GnRH release.

Question 105

How do you know a bitch is in prooestrous? Why is this important? How can you tell when oestrus starts?

Answer 105

Blood from the uterus- not like humans- it's because the uterus is hyperaemic and the vessels became leaky therefore diapedisis of erythrocytes (the further into oestrus- end up with straw coloured fluid coming out) \* To determine the onset of oestrous- the LH surge marks the onset (different than other species, which is near the end normally)-- therefore high oestrogen levels since that is stimulus for LH. \* Use progesterone (2nanograms/mL) to indirectly measure the LH surge (it starts to rise before LH surge even begins)-- this is because leutinization occurs around the edges of follicles. \* checking blood every other day- M, W, F routine

Question 106

What is unique in bitches regarding CLs?

Answer 106

Not pregnant= luteolysis. In dogs, this does not happen. Progesterone jumps and stays elevated and around 70-80 days progesterone levels peter out, marking the start of anoestrus \* parturition, luteolysis does occur= sharp drop in progesterone, non-pregnant dog gradual taper)

Question 107

What is unique in dogs regarding maturation of the oocyte?

Answer 107

Oocyte ovulates, it is ready to be fertilized. Not in dogs, dogs eggs need to mature after they have ovulated. Have not undergone second stage of meioisis. After they ovulate, second stage will occur-- therefore another 2 days are needed for the eggs to mature.

Question 108

What is meant by d0? D1?

Answer 108

d0= LH surge D1= dioestrus day 1

Question 109

What do cats and alpacas have in common?

Answer 109

Induced ovulators (cats need multiple matings, not alpacas)

Question 110

What does oestrogen in small doses do?

Answer 110

Suppresses FSH release - which can help to synchronize oestrus-- follicles have to start over again

Question 111

What is a slow release method for synchronization of cow oestrus?

Answer 111

controlled intravaginal drug release (CIDR) or progesterone impregnated intravaginal device (PRID). Implants that slowly release progesterone (+/- oestrodial)

Question 112

What is a key concept when giving PGF2alpha injections to induce luteolysis?

Answer 112

PGF2alpha does not work before the CL is 5 days old.

Question 113

How can you synchronize the oestrus cycle in cattle?

Answer 113

Can be anywhere within the oestrus cycle. Give shot of PGF2alpha. Say you have 10 cattle, 8 might respond. The ones that response, progesterone levels will drop, they will come into heat and ovulate. Come back after 12 days--\> give another shot of PGF2alpha--\> now those that did not respond in those 10 days will have ovulated and will not have a CL that is \>5 days old and will now respond

Question 114

How is the CIDR used to synchronize the oestrus cycle in cattle?

Answer 114

Mimicing progesterone curve (as you would normally get after luteolysis)

Question 115

If a farmer is having trouble synchronizing his cattle, what might you suggest?

Answer 115

Presynch: Step 1 PGF2alpha (14days) Step 2 PGF2alpha (12 days) Ovsynch: Step 1 GnRH (7 days) Step 2 PGF2alpha (2days) Step 3 GnRH + Step4 AI

Question 116

Where is semen deposited in the horse vs. cattle?

Answer 116

Horse- uterus Cattle- vagina

Question 117

What are the key features of avian reproduction system (and differences from mammals)?

Answer 117

Question 118

What are the main factors that affect ovarian activity?

Answer 118

Question 119

What is the hormonal mechanisms of repro in a female bird?

Answer 119

Question 120

What is the hormonal mechanisms of repro in a male bird?

Answer 120

Question 122

Steps of ovulation in a bird

Answer 122

Question 123

What is meant by oviposition? What is the process?

Answer 123

The process of laying eggs

Question 124

WHat is the medullary bone?

Answer 124

\* no bone marrow, but hard materials inside \* source of calcium for the egg shell

Question 125

What is brooding?

Answer 125

\* cessation of egg laying and readiness to sit on and incubate eggs \* would have to avoid in commercial production

Question 126

Calcum metabolism in birds

Answer 126

\*calcium for shell sourced from diet from skeleton \* during lay, dietary calcium needs to be3-4% for the majority of calcium to come from intestines \*Vitamin D3 promotes calcium absorption and deposition of medullary bone \* a laying bird can use its entire serum calcium in 15 minutes \* medullary bone is a buffer for maintaining serum calcium \* when mdeullary bone exhausted, cortical bone is used \* excessive loss of cortical bone leads to osteoporosis

Question 127

What is hypertosis?

Answer 127

An excessive growth of bone. Often seen in companion birds. Hyperoestrogenism might be the cause.

Question 128

Summary of chicken repro

Answer 128

Question 129

Summary of budgerigar repro

Answer 129

Question 130

Answer 130

Normally only the left persists, but occasionally both oviducts can persist

Question 131

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Question 132

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Question 133

What is different about a dog's penis vs. other mammals? Why?

Answer 133

\* (Os penis) \* bulbous glandis- bulb of cavernous tissue- why does it exist? Constrictor muscle of the bitch clamps down right behind it- muscle contration from the male pumps more blood in and constriction of sphincter muscle in the bitch prevents blood from going out- holding the penis in place. Copulation takes 30-45 minutes in dogs.

Question 134

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Question 136

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Question 137

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Question 138

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Question 139

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Question 140

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Question 141

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Question 142

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Question 144

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Question 145

Where does a dog's seminal plasma come from?

Answer 145

Prostate glands primarily.

Question 146

How do sperm propel themselves?

Answer 146

With flagellum using energy produced by: Glucose from the seminal plasma--\> oxidative respiration (adenylate kinase shuttle) & glycolysis (anaerobic conditions)--\> ATP

Question 147

Answer 147

Question 148

What happens to keep more than one sperm from penetrating the zona pellucida?

Answer 148

As soon as the sperm fuses, the cortical granules are released- they will harden the zona pellucida- so that the other sperms won't be able to penetrate it

Question 149

What is syngamy?

Answer 149

\* the male pronucleus fusing with the female pronucleus. Fusion of gametes resulting in the formation of a zygote.

Question 150

Answer 150

Question 151

Answer 151

Question 152

What does the ICM develop into?

Answer 152

Embryo

Question 153

What forms the amniotic folds?

Answer 153

Mesoderm and Trophocectoderm

Question 154

What is the chorion?

Answer 154

Merging of the mesoderm and trophoctoderm

Question 155

What is the allantochorion?

Answer 155

Mesoderm, trophoectoderm, and the allantois cavity

Question 156

What forms the lining of the amnionic cavity (called the amnion) and the chorion?

Answer 156

Both are made up of mesoderm and trophoectoderm

Question 157

Answer 157

B. 3 amnion is around the foetus attached via the umbilicus. 1 is the foetal horn. chorion and allantois are merged together. Remember -- top of the "F" is always the foetal horn.

Question 158

Answer 158