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URO 2 > 2. When to breed: oestrus and its detection > Flashcards

2. When to breed: oestrus and its detection Flashcards

1
Q

how does progesterone suppress oestrus

A
  • prepares uterus for pregnancy
  • inhibits oestrus behaviour
  • blocks LH surge
  • forms corpus luteum
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2
Q

what initiates the follicular phase

A

if not pregnant:
- uterine PGF2a
- luteolysis
- progesterone decreases
- increased oestradiol from ovulatory follicle and induce oestrus

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3
Q

describe the oestrus cycle in the normal cow

A

21 day oestrus cycle
- 17 day luteal phase then
- falling progesterone = 3 days proestrus
- standing oestrus lasts about 1 day

LH surge occurs mid-oestrus
- ovulation occurs 24 hours after LH surge
- therefore ovulation 12h after end of oestrus

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4
Q

when is the opportune time to mate the normal cow

A
  • oestrus lasts up to 1 day and ovulation occurs 12 hours after end of oestrus, thus mating occurs about 1 days prior to ovulation
  • oocytes age if not fetilised and usually cannot be fertilised >24h after ovulation (ideall sperm should be present before ovulation)
  • for AI: uterine insemination normally undertaken 6-12 hours prior to ovulation (same day as oestrus first observed)
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5
Q

how long is the duration of oestrus in the cow

A

5-18 hours

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6
Q

how long is the oestrus cycle in the cow

A

21-22 days

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7
Q

when do cows ovulate

A

12 hours after end of oestrus

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8
Q

how long is the oestrus cycle of an ewe

A

17 days

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9
Q

how long is the duration of oestrus in the ewe

A

24-36 hours

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10
Q

when do sheep ovulate

A

30-36 hours from beginning of oestrus (towards end of oestrus)

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11
Q

how long is the oestrus cycle of the sow

A

21 days

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12
Q

how long is the duration of oestrus in the sow

A

48-72 hours

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13
Q

when does the sow ovulate

A

35-45 hours from the beginning of oestrus

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14
Q

how long is the oestrus cycle of the mare

A

21-23 days [19-25d]

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15
Q

how long is the duration of oestrus in the mare

A

4-8 days

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16
Q

when do mares ovulate

A

1-2 days before the end of oestrus

17
Q

how long is the oestrus cycle of the bitch

A

210 days (varies) -7months

18
Q

how long is the duration of oestrus in the bitch

A

7-14 days

19
Q

when does the bitch ovulate

A

variable - often 2 days after onset of standing oestrus

20
Q

what is important to the timin of insemination in the cow and what are some challenges

A

relatively easy since oestrus is short and tightly regulated to time of ovulation
- inseminate/mate at oestrus

problem: detecting oestrus

21
Q

what is important about the timing of insemination in the ewe and are there any challenges

A

not a problem since mated throughout oestrus by a ram
challenge: need correct ram:ewe ratio/identification of mated ewes
Ai: insemination is slightly delayed –> 12h after onset of oestrus

22
Q

what is important about insemination in the sow and are there any challenges

A

sows/boars housed separately and sow presented to the boar for mating
- mating and AI usually start on day after the onset of standing oestrus
- 2 inseminations typically used to maximise timing when ovulation occurs
- challenge: oestrus detection is very important

23
Q

what is important about insemination of the mare and what are some challenges

A
  • return to oestrus is variable
  • oestrus length is variable
  • therefore mares are problem
  • normal practice is to teas daily and breed throughout this period or to monitor ovaries with ultrasound
24
Q

what is important about insemination of the bitch and what are some challenges

A
  • monoestrus
  • oestrus variable/very poorly indicate of time of ovulation
  • thus oestrus detection is a poor tool for planning mating
  • vaginal cytology and/or plasma progesterone measurement are better indicators
25
Q

list some oestrus behaviours in cows

A
  • stands to be mounted!!!
  • mounts other cows
  • reduced milk yield
  • brawling/restless
  • chin pressing
  • swelling of vulva, mucous discharge (bulling slime)

70% of oestrus activity occurs at night

26
Q

how do you detect oestrus in the cow and why is it important

A
  • examine cows >4 times per day for 30 mins for oestrus behaviour
  • classic detection aids (kamars, pedometers, estrotect)
  • remote/electronic aids
  • low plasma/milk progesterone indicates oestrus is imminent if previously high
  • detection of a large dominant follicle (in absence of CL)

imporatnce:
- variable time for return to cyclicity post-partum
- non-detection –> delayed breeding
- job of herdsperson as often not run with bull
- detection rates <50%

27
Q

list factors that might inhibit oestrus behaviour

A
  • hard slippery floor
  • high environmental temp
  • high milk yield
  • overcrowding
  • recent mixing/stress
  • lameness
  • feeding (big foodies)
28
Q

list signs of oestrus in the ewe

A
  • restless
  • seeks ram
  • forms a following harem
  • stands for ram
  • waggles tail
  • moves tail lateally to allow mating
  • swollen vulva
  • slight mucoid discharge
29
Q

list signs of oestrus in the sow

A
  • stands firmly to be mounted
  • vulval reddening, swelling and congestion prior to oestrus
  • seeks the boar, pacing, searching, grunting
  • stands for boar
  • responds to pheremones
30
Q

list signs of oestrus in the mare

A
  • oedema in the vulva/mucoid discharge
  • elevated tail and lean her hindquarters towards the stallion
  • spread hindlegs
  • winking
  • flehmen response in stallion
  • commonly daily teasing is performed
  • detection of large follicle on US and absence of CL
  • thickened wall of follicle as approaches ovulation
31
Q

list signs of oestrus and pro-oestrus in the bitch

A

pro-oestrus
- very long (9 days)
- bitch is attractive but not allow mating
- vulval swelling
- presence of a serosanquinous discharge

oestrus:
- stands to be mated
- deviation of tail
- discharge becomes paler in colour
- reduction in vulval oedema
- assessment of vaginal epithelial cells (clinical)
- plasma progesterone concentrations (clinical)

32
Q

discuss oestrus in the queen

A
  • pro-oestrus: short and often unnoticed
  • induced ovulator
  • LH response to mating decreases with each day of oestrus and follicles ultimately regress (oestrus detection important)

signs of oestrus:
- increased vocalisation, rubbing and rolling
- increased activity and will seek tom
- possible slight mucoid vulval
- extending hindlegs and demonstrating lordosis
- erect tail held to one side

33
Q

what is silent oestrus and why does it occur

A

ovulation without signs of oestrus
- typically at first oestrus after seasonal anoestrus or partuition
- no pregesterone priming on brain centres
- no progesterone fall to trigger oestrogen receptor expression in brain
- no sudden release of oestradiol

34
Q

how long is oestrus in the cow

A

18 hours

35
Q

when is AI typically first conducted on sow

A

day after oestrus first observed

36
Q

what clinical tool can we use to optimise the time of mating in the dog

A

blood progesterone

URO 2 (106 decks)

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