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FARM ANIMAL > 17.4.1: Introduction to farm animal reproduction > Flashcards

17.4.1: Introduction to farm animal reproduction Flashcards

1
Q

True/false: you can tell about the cow’s cyclicity from her cervix.

A

False
Cervix tone is discussed in horses but not in cows

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2
Q
A

Dominant follicle
* Contains oocyte
* Fluid filled (anechoic on ultrasound)
* Secretes oestradiol -> this drived oestrus

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3
Q
A

Corpus luteum
* Highly vascularised transient endocrine gland
* Solid (homogenous, medium echogenicity)
* Produces progesterone

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4
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9
Q

High levels of which hormone lead to an LH surge? What is the effect of the LH surge?

A

Oestradiol
Effect of LH surge = ovulation

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10
Q

How long is the oestrus cycle in the cow?
How long is the luteal phase?
How long does standing oestrus last?

A
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11
Q

You see a cow showing signs of oestrus. When should you AI?

A

Oestrus lasts ~ 1 day so ASAP!
In an ideal world, would AI 6hrs after the onset of oestrus; in practice, just AI as soon as you see oestrus.

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12
Q

What will the ovaries feel like when a cow is on Day 1 of her cycle?

A

Day 1 = ovulation has just occurred
The ovaries will be small and it might be hard to palpate the tiny CL

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13
Q

If you see a large CL and a large follicle present at the same time, which one is dominant?

A

The CL

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14
Q

Which structures can you see on this ovary?

A

There is a small follicle (anechoic structure)

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15
Q

Which structures can you see on this ovary? Which is likely to be dominant?

A
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16
Q

What phase of her cycle is this cow in?

A

Follicular phase

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17
Q

These two ovaries are from the same cow. What phase of her cycle is she in? Which structure will be dominant?

A
  • She is mid-luteal phase
  • She has a large follicle but the CL will dominate
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18
Q

1

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19
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21
Q

True/false: the first oestrus after parturition is typically silent.

A

True

22
Q

How long after parturition should a dairy cow have had her first ovulation by?

A

3 weeks after parturition

23
Q

In which species do we see profound lactational anoestrus (in that while the young are there and suckling, she will not cycle)? What is the hormonal mechanism behind this?

A

Sow
Prolactin suppresses LH, thus there is no ovulation

24
Q

Why might we see anoestrus?

A
  • Physiological reasons: gestation, lactation/presence of offspring (species differences), seasonality (long or short day breeders)
  • Pathology: metabolic/ heat stress, ovarian pathology e.g. cystic ovarian disorders, inactive ovarian activity
25
Q

How soon after piglets are weaned would you expect a sow to ovulate?

A
  • Weaning intiates oestrus and there should be an LH surge within 7 days
  • This may be affected by length of lactation, timing of weaning
26
Q
A

Cystic ovary

27
Q

True/false: GnRH will induce oestrus.

A

False
* GnRH induces an LH surge and therefore ovulation (approx. 28hrs later)
* If you give GnRH, AI the cow 6hrs later
* It does not induce oestrus

28
Q

True/false: we can use GnRH to force ovulation/ luteinisation of cystic structures.

A

True

29
Q
A

Multiple growing follicles on both ovaries

30
Q

What is the effect of FSH and what are its clinical uses?

A

FSH stimulates antral follicle growth. There are few products that are FSH-specific; we can use eCG as this has mainly FSH-like activity.

Clinical uses:
* Superovulation: ovulation of more follicles than norma
* Must administer early in the follicular wave for superovulation
* Often requires repeated doses
* Responses are varied

31
Q

What effect does LH have and how can we use it clinically?

A

We don’t have an LH-specific product; we use hCG instead as this is LH-like in activity.
This stimulates the final maturation of follicles, causes luteinisation and provides luteal support.

Clinical uses (exact effect influenced by dose)
* Induce ovulation when animals are in oestrus
* To force ovulation when there has been repeated failure of conception in cattle
* Treatment of cystic ovaries in cows and heifers

32
Q

What effect do progestogens have and what can we use them for clinically?

A

Progestogens -> negative feedback effect on the pituitary (mimics luteal phase)

Clinical use:
* Suppress the HPG axis
* Used as a method of inducing/ synchronising oestrus by administration and withdrawal of the product
* When we withdraw the product, cow will enter the follicular phase

33
Q

What is flugestone and what does it do?

A
  • Progestogen vaginal sponge
  • Oestrus induction/ synchronisation upon withdrawal
  • Often used in combination with eCG
34
Q

What is a PRID/CIDR and what does it do?

A
  • Vaginal device release progesterone
  • Oestrus induction/ synchronisation on removal
  • Often used in combination with GnRH
35
Q

What is altrenogest (a.k.a. Regumate) and what does it do?

A

Exogenous progestogen
* Oral liquid
* Used for oestrus suppression/ induction/ synchronisation in mares and sows

36
Q

How old does a CL need to be in the cow to respond to prostaglandin?

A

Must be over 6 days old to respond

37
Q

What must you ensure before giving PGF2a to an animal?

A

Ensure that she is not pregnant

38
Q

What physiological effects does PGF2a have?

A
  • Lysis of the mature CL, causing progesterone to decline
  • Smooth muscle contraction (ecbolic effect on the uterus)
39
Q

What are the clinical uses of PGF2a?

A
  • Termination of luteal phase to synchronise oestrus
  • Induction of abortion
  • Induction of parturition
  • Ecbolic efect: treatment of chronic metritis, treatment of pyometra is CL is present
40
Q

How soon after giving PGF2a to lyse a CL will a cow come into oestrus?

A

3-4 days after PGF2a

41
Q

Which protocol is pictured here?

A

P4 and PGF. This is followed by fixed time AI.
This can be used in the cow or heifer.

42
Q

Which synchronisation protocol is pictured here and what animals is it used in?

A

OvSynch
Used in cows

43
Q

Which synchronisation protocol is pictured here and what animals is it used in?

A

OvSynch with P4
Heifers

44
Q

True/false: melatonin can be used to induce cyclicity in sheep.

A

True

45
Q

True/false: it is common to use 2 doses of PGF2a in sow synchronisation protocols.

A

False
* Unable to use 2 doses of PGF2a in the sow because CL only responds after day 11

FARM ANIMAL (53 decks)

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