Detecting oestrus

Question 1

Why does standing oestrus occur a day before ovulation?

Answer 1

As the oocytes age if not fertilised and usually cannot be fertilised >24h after ovulation.

Question 2

If the cow is in standing oestrus the day before ovulation, why do we AI a cow 6-12h before ovulation?

Answer 2

Frozen semen is deposited in the uterus and survives the freezing well.

Question 3

What are the problems with timing of mating in the cow?

Answer 3

In the cow knowing when to mate is reliable however it can be difficult to detect oestrus.

Question 4

What are the problems with timing of mating in the ewe?

Answer 4

In the ewe timing of mating is not a problem as the ram is left in with the ewes (or AI 12h after the onset of oestrus) the issue is getting the correct ratio of rams to ewes and identifying mated ewes.

Question 5

What are the problems with timing of mating in the pig?

Answer 5

For pigs oestrus detection is very important as boars and sows are housed separately, mating and AI are ususally done 2 days after the onset of standing oestrus and two inseminations are done.

Question 6

What are the problems with timing of mating in the mare?

Answer 6

Mares are more difficult as they have a long oestru sand oestrus length is variable, common practice is to tease daily and breed throughout this period (or to monitor ovaries with ultrasound)

Question 7

What are the problems with timing of mating in the bitch?

Answer 7

With bitches Oestrus is very variable and signs relate very poorly to the time of ovulation so vaginal cytology can be used and/or with plasma progesterone measurement.

Question 8

What is the duration of oestrus in the cow and how does this relate to ovulation?

Answer 8

5-18h and it occurs 12h before ovulation

Question 9

What is the duration of oestrus in the ewe and how does this relate to ovulation?

Answer 9

24-36h and it occurs 30-36 hours from the onset of oestrus ie. at the tail end of oestrus

Question 10

What is the duration of oestrus in the sow and how does this relate to ovulation?

Answer 10

48-72h and it occurs 35-45 hours after the onset of oestrus ie. just after oestrus

Question 11

What is the duration of oestrus in the mare and how does this relate to ovulation?

Answer 11

4-8 days and ovulation is 1-2 days before the end of oestrus

Question 12

What is the duration of oestrus in the bitch and how does this relate to ovulation?

Answer 12

7-14 days and ovulation is often 2 days after the onset of standing oestrus

Question 13

Name some signs of a cow coming into standing oestrus

Answer 13

Mounts other cows, reduced milk yield, restless, chin pressing and swelling of the vulva with mucus

Question 14

Name some detection aids that could help in identifying cows coming into heat

Answer 14

Kamars (mounting breaks them red), pedometers, gps

Question 15

Low levels of what hormone in the milk and plasma would suggest a cow is coming into oestrus?

Answer 15

Progesterone

Question 16

A fall in what body parameters could suggest a cow is coming into heat?

Answer 16

Temperature and vaginal pH

Question 17

How can we tell if a cow is about to come into oestrus by ultrasound?

Answer 17

Detection of a large follicle and the absence of a CL

Question 18

What factors could mask oestrus behaviour in the cow?

Answer 18

Concrete reduces oestrous behaviour by up to 50% especially when wet and slippery
High environmental temperature
Overcrowding
Recent mixing / stress
Lameness

Question 19

What can we do to eliminate the need for oestrus detection?

Answer 19

Synchronisation of ovulation

Question 20

What are the signs of oestrus in the ewe?

Answer 20

Restless - Seeks the ram, Forms a following harem
Stands for the ram - waggles tail, moves tail laterally to allow mating
Vulva - Slightly swollen, Slight mucoid discharge

Question 21

How could we detect oestrus in the ewe? (not common)

Answer 21

Use a vasectomised ram with a raddle or detect low plasma progesterone

Question 22

What are the signs of oestrus in the sow?

Answer 22

Vulval swollen and congested prior to oestrus
Seeks the boar and stands firmly to be mounted (the back pressure test; very reliable)
Restlessness with repetitive grunts/ Pacing and searching
Lowered feed intake and loss of appetite
Red, swollen vulva and increase in vaginal mucus
Response to boar pheromones

Question 23

When will sows come into heat after weaning? When should they be served?

Answer 23

Sows coming into heat soon after weaning (day 3-4) will show oestrus over 3 days, so insemination must be begun on day 2-3 of heat.
Sows with an average interval from weaning to onset of heat (5 days) present a heat period of approximately 2 days and should be inseminated 24h after heat onset, with a second insemination to be done 12h later.
Sows showing delayed heat after weaning (day 6 and beyond) tend to show heat only for a short period (1 day) indicating that insemination should be performed within 24h of heat detection.

Question 24

Why is oestrus detection in the mare important?

Answer 24

If she is not in oestrus she may damage the stallion

Question 25

When do mares return to oestrus after foaling?

Answer 25

Generally mares return to oestrus about 6-10 days after foaling
This is called the ‘foal heat’ because often the foal develops diarrhoea at this time and the oestrus is therefore easy to detect
But fertility may not always be high at the foeal heat oestrus
Mares with an older foal at foot may not show signs of oestrus as they are protective of the foal (‘foal shy’)

Question 26

What are the signs of oestrus in the mare?

Answer 26

Vulva: Oedema / mucoid discharge
Elevated tail and lean her hindquarters towards the stallion
“winking” (repeated exposure of clitoris)
Induces “flehmen” response in stallion
Commonly, teasing is performed (usually daily) using a less valuable stallion over a ‘teasing board’

Question 27

How can we detect oestrus in the mare by ultrasound?

Answer 27

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

Question 28

How do we detect proestrus in the bitch and how long does this last?

Answer 28

Very long (classically 9 days)
Bitch is attractive but not allow mating
Vulval swelling
Presence of a serosanguinous (bloody) discharge

Question 29

How do we detect oestrus in the bitch and how long does this last?

Answer 29

9 days
Standing to be mated
Deviation of tail
Discharge becomes paler in colour
Reduction in vulval oedema

Question 30

What other methods can we use in the bitch to detect oestrus?

Answer 30

Oestrus in the bitch can be detected by:
vaginal cytology
Assessment of vaginal epithelial cells
Assessment of vulval softening
Examination of the appearance of the vaginal wall
Plasma progesterone concentrations (detecting a rise in progesterone that precedes ovulation)

Question 31

What would we expect to see on vaginal cytology in a bitch coming into oestrus?

Answer 31

Most, but not all, bitches will undergo full cornification, and the smear will reveal a monotonous pattern composed almost exclusively of anucleate superficial cells.
If the bitch has been bred within a day of preparing a vaginal smear, it is quite likely that sperm will be observed among the epithelial cells.

Question 32

In the queen the LH response to mating ……………… with each day of oestrus until…………..

Answer 32

Decreases

The follicles regress

Question 33

What are the signs of oestrus in the queen?

Answer 33

Stand to be mated by lowering her front quarters,

extending her hindlegs and demonstrating lordosis – the tail is erect and held to one side

Question 34

In induced ovulators mating will cause the release of the oocyte, but what are the prerequisites?

Answer 34

Presence of antral follicle and increased oestrogen still prerequisite for LH release and ovulation

Question 35

What is silent oestrus?

Answer 35

Silent oestrus is Ovulation with limited signs of oestrus and often at first oestrus after seasonal anoestrus / parturition
No progesterone priming
No progesterone fall
No sudden release of oestrogen or LH suppression