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AN SC 312 > 10 - Avian Female Reproduction > Flashcards

10 - Avian Female Reproduction Flashcards

1
Q

Describe egg formation broadly

A

Egg formed inside out
Yolk is released from the ovary into the oviduct at ovulation. Travels through the oviduct then other components like egg white, egg shell and membranes are deposited around the yolk

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2
Q

What is the germinal disk

A

Where fertilization happens if there is sperm in the oviduct

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3
Q

Why does the egg yolk have dark and light layers

A

Yolk deposited when the gut is empty is lighter, when feed was in the gut is darker

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4
Q

What is the chalaza

A

“Bungee cord”
Part of egg white/albumen
Twisted around yolk to hold it in the middle of the egg (if yolk hits egg shell, fertilized germinal disk may be compromised = embryonic mortality)

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5
Q

What are the shell membranes

A

Attached everywhere except on the larger side of the egg (air cell)

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6
Q

What is the point of the air cell

A

Allows gas exchange
When embryo is big enough it cracks the shell with its beak there

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7
Q

Parts of the avian oviduct

A
  1. Infundibulum
  2. Magnum
  3. Isthmus
  4. Shell gland
  5. Vagina
  6. Cloaca
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8
Q

Slide 6

A

Important

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9
Q

When do follicles appear in birds

A

All the follicles (ova/yolks) ever required are present as very tiny follicles at the time she hatches

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10
Q

How many ovaries in chickens and turkeys? What happens to mature follicles

A

Only one (left)

They are released from the ovary (ovulated)

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11
Q

What is the POF

A

Post-ovulatory follicle (called CL in mammals)
No role in avian species, remains inactive after ovulation

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12
Q

When/what produces progesterone in avian species

A

F1 (mature) follicle produces progesterone BEFORE ovulation
In mammals, CL produces it after ovulation

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13
Q

What is the stigma

A

Clear part of the yolk (no blood vessels) where ovulation occurs
It ruptures and the yolk is released into the oviduct (no bleeding during ovulation)

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14
Q

Four different kind of follicles in birds, ranked from largest to smallest

A
  1. Large yellow follicles (largest)
  2. Small yellow follicles
  3. Large white follicles
  4. Small white follicles (smallest)

Slide 10*

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15
Q

What matters most with regards to what follicle ovulates?

A

Follicle maturation, not size
If it is producing enough P4 it is mature enough to ovulate

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16
Q

Slide 12

A

Yolk deposition pattern

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17
Q

What is the structure of the follicle (cells present, their roles)

A

Granulosa cells around yolk: produce progesterone

Theca cells on outside: produce estradiol and androstenedione hormones

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18
Q

What do androgen hormones do

A

Involved in feather patterns and comb growth in females

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19
Q

Yolk color depends on… Different colours and why they are like that

A

On nutrition! (not health, housing)

  1. Orange colour = fed pepper, alfalfa meal
  2. Pale yellow = wheat-based diets
  3. Dark yellow: corn-based diets
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20
Q

Function of the infundibulum, and how long the ova spends there

A

Funnel shaped entry point for an egg yolk to be picked up as it ovulates from the ovary
Location for fertilization

Duration 15 mins

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21
Q

Function of the magnum, how long the yolk spends there

A

Addition of albumen (egg white) around yolk

Duration 3 to 4 hours

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22
Q

Function of the isthmus, how long the ova spends there

A

Inner and outer shell membranes are added around the egg yolk and white

Duration 1 hour

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22
Q

Function of the shell gland, how long the yolk spends there

A

Addition of shell material (mainly calcium carbonate) + pigments (e.g. brown, blue)

Duration 21 hours

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23
Q

Function of the vagina, how long the ova spends there

A

Passage way for the egg from the shell gland to the cloaca.
Waxy cuticle film (bloom) is applied to seal egg pores and to prevent the egg from dehydrating

Duration <1 min

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24
Q

Why do we get eggs in the fridge in NA

A

We wash eggs bc of salmonella risk, which removes the bloom and exposes the egg to contamination through the egg shell pores
In Europe, they do not wash and can keep the eggs outside

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25
Q

Where does the chalaza form

A

In the magnum as the developing egg rotates traveling down it

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26
Q

Air cell is important in… When does it grow

A

Hatching process for chicks

Increases in size as egg loses moisture, either through storage or incubation

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27
Q

Egg shell colour depends on…

A

Genetics (not nutrition or bird health)

Look at slide 19

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28
Q

What are SSTs? Where are they located?

A

Sperm storage tubules, in

Primary storage site at utero-vaginal junction

Secondary sperm storage site in the infundibulum

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29
Q

How long can sperm survive in female domestic birds?

A

2-15 weeks
After oviposition, stored sperm travel through oviduct to infundibulum to fertilize the next ovulated follicle/yolk

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30
Q

What is the vent

A

Common external opening: urine feces and egg all excreted from cloaca
Hen can invert her cloaca during mating and laying, so the egg exits directly from the shell gland

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31
Q

Primary control center of reproduction in hens

A

HPG axis
Hypothalamus Pituitary Gonad

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32
Q

Role of the hypothalamus in hen reproduction

A
  • receives and sends signals via neurotransmission
  • releases Gonadotropin-releasing hormone and/or gonadotropin-inhibiting hormone
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33
Q

Role of the anterior pituitary in hen reproduction

A
  • receives signal from hypothalamus, feedback from ovary
  • releases gonadotrophins (LH and FSH)
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34
Q

Role of ovary in hen reproduction

A
  • follicle pool
  • produces estradiol and progesterone
35
Q

The hypothalamus must be…

A

mature to respond to photostimulation

36
Q

Factors affected GnRH and GnIH release from the hypothalamus

A

Environmental: light, nutrition, temperature, stress
Intrinsic: metabolic status (body composition, growth trajectory)

37
Q

Function of GnRH in hens

A

Travels via portal bloodstream to anterior pituitary to stimulate production and release of FSH and LH

38
Q

Function of LH in hens

A

Baseline: pre-hierarchical follicle E2 production
Peak: progesterone production in F1 granulosa cells, causing ovulation

39
Q

Function of FSH in hens

A

Follicle growth and steroid hormone production

40
Q

Role of estradiol in hens

A

Released by small white follicles
In ovary: sexual maturation process (maturation of follicles)
In liver: production of yolk lipis

41
Q

Role of progesterone in hens

A

Released by pre-ovulatory follicle (F1)
Positive feedback to the hypothalamus: causes LH surge, ovulation

42
Q

Organs associated with yolk forming tissues, albumen forming tissues and shell forming tissues

A

yolk: liver

Albumen: oviduct

Shell: skeletal system, oviduct (shell gland)

43
Q

Difference in calcium use in rearing vs laying phase. What is cage fatigue?

A

Rearing (0 to 16 weeks) = calcium deposition into bones

Laying = calcium released to blood to synthesize egg shell

When calcium needs to be taken from structural bones = cage fatigue

44
Q

What is oviposition

A

Laying down of an egg. Follows ovulation by 24-28 hours and occurs in sequences

45
Q

What is a laying sequence

A

Period of several days of continuous laying of one egg per day

46
Q

What is the open period for LH release

A

6 to 8 hour period of the day in which LH level is high and a hen can ovulate
LH “office time”
Beyond this time, if follicle becomes mature, does not ovulate until LH releases next morning

47
Q

What is the scotophase

A

Dark period of the photoperiod

48
Q

What is pause

A

Each laying sequence separated by non-laying day known as pause

49
Q

What is photoperiod

A

Number of hours of daylight and darkness that birds are exposed to in a day
Photophase vs scotophase

50
Q

Determinate vs indeterminate layers

A

Determinate:
- avians that ovulate a defined number of follicles (1-4 usually) in a clutch
- clutches separated by period of incubation and rearing of young
- typically 1 (maybe 2) clutches a year

Indeterminate:
- avians that continue to ovulate if eggs are removed
- laying occurs in sequences
- eventually production ceases and birds become photo-refractory

51
Q

Slide 29***

A

Laying sequence or clutch

52
Q

What is a prime sequence in hens? Usually occurs when? Typical prime sequence length

A

Longest laying sequence of a hen (chicken PB)

Usually occurs about the time of peak production (32 weeks)

Egg type hen: 60 days
Broiler breed: 20 days

53
Q

What makes prime sequences longer

A

Faster follicle maturation rate

54
Q

What is lag

A

Different (in hours) between the laying of eggs in a laying sequence
E.g. an egg laid at 9am one day followed by 11am the next day = 2 hour lag

55
Q

Long lag times are related to…

A

Slow rates of follicular maturation and result in short sequences

56
Q

What is different about the first egg in a sequence? Why?

A

Always heavier
Not due to yolk mass, but egg white mass

57
Q

What is ovulation? Governed by

A

Process which occurs when a ‘mature’ follicle is released from the ovary

Governed by circadian cycle (LH surge) and follicle maturation rate

58
Q

Mature follicle is…

A

capable of producing progesterone

59
Q

When does ovulation occur during the day

A

Defined period known as the ‘open period for LH release’

60
Q

What is a ‘mature’ follicle? What is ovulation governed by?

A

One that is capable of producing progesterone
Governed by circadian cycle (LH surge) and follicle maturation rate

61
Q

Slide 37, 38

A

Too much info

62
Q

Three mechanisms of light stimulation

A
  1. Pineal stimulation
  2. Hypothalamic stimulation
  3. Retinal stimulation
63
Q

Two important phases that cause photostimulation in birds

A
  • dawn
  • photosensitive phase (11 to 13 hours after dawn): dictates whether birds perceive day as being long or short

Slides 47, 48

64
Q

Functions of photostimulation

A
  • cue sexual maturity in all birds
  • limit broodiness
  • create conditions for longer sequences
65
Q

Rearing photoperiod, critical day length and laying photoperiod

A

RP: short days, limits sexual maturation, 8 hours, constant or decreasing, NOT increasing

CDL: minimum photoperiod needed to stimulate sexual maturation

LP: day length that meets critical day length, 14-16 hours, constant or increasing, NOT decreasing

66
Q

Hemeral day, ahemeral day, short ahemeral day, long ahemeral day

A

HD: normal 24 hour day

AD: day in which photoperiod and scotoperiod do not add up to 24h
SAD: adds up to less than 24h, used in genetic selection of birds with faster follicle maturation
LAD: add up to more than 24h, match day length and ovulation rate

67
Q

How is black out housing achieved

A

Dark-out shields/light traps on air intakes and exhaust fans

68
Q

What is photorefractoriness

A

Condition in which the existing photoperiod does not provide adequate stimulation to sustain repro fxn

69
Q

Advantages of photorefractoriness, outcomes

A

Prevents animals from becoming sexually active when environmental conditions are unfavourable
Birds cease laying

70
Q

What is juvenile photorefractoriness

A

Chicks hatch with photorefractor
Males and females will not respond to light stimulation unless they have been exposed to period of short days then long days

71
Q

What is adult photorefractoriness

A

Loss of response to long day length
Gonadal regression due to env stress

72
Q

Important factors for initiation of puberty

A
  • day length
  • age (hypothalamic maturity)
  • body weight
  • body composition
  • metabolic status
73
Q

Changes in hen during puberty

A

Comb grows large and bright red
Pubic bones widen to allow egg
Oviduct enlarges and becomes active
Liver starts making egg yolk type fat

74
Q

Slide 64

A

Condition at sexual maturation

75
Q

Why is broiler breeder growth management difficult? Solution

A

High potential for growth, but need to lay eggs which can be contradictory

Solution is feed restriction program to control excessive growth

76
Q

What is erratic oviposition defective egg syndrome in broilers breeders

A

Random ovulation
Random oviposition
High incidence of multiple yolked eggs, or multiple eggs per day
Shell defects
Follicular atresia

77
Q

Symptoms of not enough follicles, presumed causes

A

Normal peak production but poor persistency (short sequences)

Inadequate light stim, high incidence of atresia, normal decline in follicle # w age

78
Q

Symptoms of too many follicles, presumed causes

A

Excellent peak production, poor persistency, poor shell quality, double-yolked eggs

Birds fed aggressively coming into production

79
Q

Principle for breeder feeding management

A

Make feed increases as small and as frequent as possible
Avoid sudden large increases

80
Q

Examples of reproductive disorders in hens (10)

A
  • two eggs in an oviduct
  • double yolk egg n broiler breeders
  • two eggs close to each other in an oviduct
  • two eggs attached
  • large follicle atresia
  • internal ovulation
  • internal oviposition
  • two oviducts
  • phantom follicles
  • cystic ovaries
  • multiple layers of shell membrane
81
Q

Why do internal ovulation and oviposition occur

A

Ovulation: ovulated follicle into abdominal cavity (infundibulum did not catch)

Oviposition: lay egg inside abdominal cavity (moved backward, tear in shell gland)

82
Q

What are phantom follicles

A

Unreconciled post-ovulatory follicles
Thought to represent internal ovulation

83
Q

What are cystic ovaries

A

Fluid accumulates around it due to:
- anatomic abnormalities on ovary
- chronic inflammation
- pathological condition of ovary

84
Q

What is broodiness

A

Beh exhbitied when they want to incubate egg
Prolactin hormone
Ceases egg production (follicle atresia)

AN SC 312 (31 decks)

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