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Flashcards in The oestrus cycle Deck (25)
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1
Q

Give examples of polyoestrus animals that cycle constantly throughout the year?

A

Cow, pig and rodent

2
Q

Give examples of seasonal oestrus cycle animals that cycle during a specific season?

A
Long day (spring, mare and deer)
Short day (autumn, ewe)
3
Q

Give and example of a monoestrus animal that has infrequent cycles independent of season?

A

Dogs.

4
Q

What are some of the methods used to manipulate seasonal breeders?

A

Artificial change to photoperiod i.e. put mares
& stallions under lights at Xmas.
Physical change to photoperiod i.e. “shuttle”
stallions travel from northern to southern hemispheres
biannually.

5
Q

What are the signs of oestrus in the female?

A

— Is receptive to the male (lordosis) &

— has high levels of oestrogens

6
Q

What are the signs of dioestrus in the female?

A

— rejects the male &

— has high levels of progesterone

7
Q

What are phases of the oestrus cycle?

A
Prooestrus* — phase immediately before
oestrus
Oestrus
Metoestrus* — succeeds oestrus, corpus
luteum forms
Dioestrus
*not obvious in all species
8
Q

What stage of the oestrus cycle is the bitch likely to be in during the follicular and luteolytic phase and which hormone governs this?

A

Pro-oestrus and oestrus.

Oestrogen.

9
Q

What stage of the oestrus cycle is the bitch likely to be in during the luteal phase and which hormone governs this?

A

Metoestrus and dioestrus

Progesterone

10
Q

What does FSH do?

A

Stimulates maturation of germ cells (all stages of gametes)

11
Q

What does LH do in the male and the female?

A

. luteinising hormone stimulates production & secretion of steroids:
— testosterone in testes
- oestrogen & progesterone in ovaries

12
Q

What are some oestrus detection methods used in cattle?

A

Kamars, pedometers, estrotect, GPS, Van Eerdenbergs scoring, Low plasma/milk progesterone, crystallisation patterns in the vaginal mucus, a fall in body temperature prior to oestrus, a reduction in vaginal pH
10 15 Days in relation to ovulation

13
Q

What factors can inhibit oestrus behaviour in cows?

A
— Hard, non-supportive floor is best
— Concrete reduces oestrous behaviour by up to 50%
especially when wet and slippery
— High environmental temperature
— Overcrowding
— Recent mixing / stress
— Lameness
- FEEDING
Think of poor observation first
14
Q

What can be used in cows to synchronise ovulation?

A

Ovsynch

15
Q

Signs of oestrus in the sow?

A
VuIva swollen and congested prior to oestrus
Seeks the boar
Stands firmly to be mounted (the
back pressure test (she won’t move
when you put pressure on her; very
reliable)
16
Q

Signs of oestrus in the mare?

A

Detection of a large follicle (>20mm) in absence of a CL)
(by palpation or ultrasound examination)
Demonstration of follicle size, follicle wall thickening, follicle softening on ultrasound examination

17
Q

How long does proestrus typically last in the bitch and what are the signs?

A
— Very long (classically 9 days)
— Bitch is attractive to the male but will not allow
mating
—Vulvalswelling
— Presence of a serosanguinous discharge
(bloody discharge from vulva)
18
Q

What are the signs of oestrus in the bitch and what is the average length?

A
. Oestrus: 9 days
— Standing to be mated
— Deviation of tail
— Discharge becomes paler in colour
— Reduction in vulvaloedema
19
Q

What is the most effective method of oestrus detection in the bitch?

A

Vaginal cytology

Should see anucleate epithelial cells during oestrus

20
Q

What kind of ovulators are cats?

A

Induced ovulators.
LH response to mating decreases with each day
of oestrus and follicles ultimately regress

21
Q

What are signs of oestrus in the queen?

A

. Increased vocalisation, rubbing and rolling
. Increased activity and will seek tom
. Possible slight mucoid vulval discharge

22
Q

What is an induced ovulator? And what species exhibit this?

A

— The presence of an antral follicle and increased oestrogen are still prerequisite for LH release and ovulation HOWEVER, copulation results in neuro-endocrine response resulting in LH release and then ovulation
- Examples: cat, rabbit, ferret, mink, camelids

23
Q

What are the series of hormonal events that lead to dominant follicle selection?

A

Oestradiol and inhibin increase causing FSH to drop and subordinate follicles to degenerate.

24
Q

What sequence of hormonal events initiates ovulation?

A

Non pregnant uterus secretes PGF2a, causing luteolysis, meaning progesterone drops, oestradiol is secreted from ovulatory follicle causing an LH surge and next ovulation.

25
Q

What does pseudopregnancy happen in the bitch?

A

She has no LP shift. Progesterone is produced throughout pregnancy by the ovary. Prolaction also maintains the CL.