Intro to farm animal repro Flashcards

1
Q

What is the most useful landmark when palpating repro tract

A

cervix

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2
Q

What does a follicle secrete

A

oestradiol- drives oestrus

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3
Q

what does a corpus luteum produce

A

progesterone

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4
Q

what is corpus luteum

A

highly vascularised, transient endocrine gland

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5
Q

what do a CL look like on Ultrasound

A

homogenous medium echogenicity

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6
Q

When does ovulation occur in the cow

A

12hrs after end of oestrus

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7
Q

If a CL is 20 mm what does this mean

A

CL is either growing or regressing

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8
Q

How long is the duration of oestrus in the cow

A

5-18hrs
will ovulate 12hrs after end of oestrus

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9
Q

How long is the oestrus cycle in the cow

A

21-22 days

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10
Q

How long is the oestrus cycle in the ewe

A

17 days

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11
Q

How long is oestrus in the ewe

A

24-36 hrs
ovulate 30-36 hours from begging of oestrus

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12
Q

How long is the oestrus cycle in the sow

A

21 days

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13
Q

how long is oestrus in the sow

A

48-72hrs
ovulate 35-45 hours from beggining of oestrus

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14
Q

What is the main oestrus detection method in the sow

A

back pressure test

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15
Q

Describe the resumption of full ovarian activity after parturition

A

At parturition, pituitary isrefractory to GnRH, but
FSH secretion initiated due to lack of negative feedback, this leads to emergence of an antral follicular wave
Increasing sensitivity of gonadotropes to GnRH, leading to
Increased FSH-stimulation of oestradiol production
Increased LH pulse frequency
Ovulation, often accompanied by silent oestrus

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16
Q

List 3 causes of physiological anoestrus

A

gestation
lactation/ presence of offspring
seasonality

17
Q

List 2 causes of pathologuical anoestrus

A

stress- metabolic or heat
ovarian pathologies - Cystic ovarian disorders or Inactive ovarian activity

18
Q

How does suckling cause anoestrus in the sow

A

Early follicular activity but
Prolactin suppresses LH secretion, thus no ovulation

19
Q

Deescribe how sows return to oestrus

A

Weaning ‘initiates’ oestrus and LH surge within 7 days (WOI)
Weaning to oestrus interval (WOI) is affected by length of lactation / timing of weaning

20
Q

what does giving synthetic GnRH do

A

Hastens impending cyclicity/ return to oestrus
Hastens ovulation by inducing LH surge. - if dominant follicle there
“Force” ovulation/luteinisation of cystic structures

21
Q

what does giving synthetic FSH do

A

Stimulates antral follicular growth- results in multiple dominant follicles- embryo transfer

22
Q

How is synthetic progesterones used

A

Progesterone has a negative feedback effect upon the hypothalamus and anterior pituitary
Suppress the hypothalamic-gonadal axis thus:
Used as method of inducing/synchronising oestrus following withdrawal of the product

23
Q

what does prostaglandin F2a do

A

Lysis of the mature CL, causing progesterone to decline
Smooth muscle contraction i.e. ecbolic effect on uterus

24
Q

After administration of PGF2a when will the cow come into oestrus

A

3-4 days after PGF2a administration- if there is a mature follicle

25
Q

Why can’t we use 2 doses of PGF2a in sows

A

Cl only responsive day 11-16

26
Q

List 3 ways to stimulate onset of early cyclicity in sheep

A

Melatonin
Progestogen sponges in combination with eCG/GnRH
Ram effect