Bovine Reproductive Cycle

Question 1

What exogenous factors affect the bovine oestrus cycle?

Answer 1

Adiponectins
Stress
NEB
Photoperiod

Question 2

What prevents a dominant follicle from ovulating in a follicular wave?

Answer 2

High progesterone
The follicle undergoes atresia

A dominant follicle will only ovulate when progesterone is low

Question 3

Describe the resumption of cyclicity post-calving?

Answer 3

1st follicular wave ovulates and there is a short lived CL
= ovulate a silent oestrus between 14-18 days

Then normal cyclicity resumes

The cow will only start cycling again once the calf is removed

Question 4

What factors reduce LH pulse frequency and delay return to cyclicity?

Answer 4

Sucking calf
Declining NEB
Poor BCS at calving 
Low DMI
Disease

Question 5

How long is the bovine oestrus cycle?

Answer 5

21d

Question 6

Oestrus lasts how long in cow?

Answer 6

18h

Question 7

When does the LH surge occur in relation to the onset of oestrus?

Answer 7

6 hours

Question 8

What is the main indicator of oestrus in the cow?

Answer 8

Standing to be mounted

Question 9

Lost some aids for detecting oestrus?

Answer 9

Tail paint / chalk 
Record keeping - observe 18 days from last oestrus
Chin balls
Teaser Bulls
Activity meters 
Pedometers
Heatime

Question 10

What temperature should you thaw frozen semen at?

Answer 10

37c for 40s

Question 11

What would you expect on a vaginal exam for a cow in oestrus?

Answer 11

Bulling string

Open cervix

Question 12

How long after calving should you expect the first ovulation in a cow?

Answer 12

14-18d if no CL

Question 13

What would you expect the uterus to feel like in a 3 month pregnant cow?

Answer 13

Small cotyledons
Ballot a melon sized calf
Uterine artery pulse on pregnant horn

Question 14

At what stage can you palmate fremitus in the uterine artery?

Answer 14

5m pregnant horn

6m non-pregnant horn

Question 15

From how many days can you confidently scan for pregnancy?

Answer 15

28

Question 16

What are you looking for on a post natal check?

Answer 16

Endometritis
Tears
Return to cyclic activity
Whether the cervix is open or closed

Question 17

When is the use of a PRID contraindicated?

Answer 17

Any infection of the reproductive tract

Causes vaginitis and local immunosuppression

Question 18

How soon after injecting a cow that has a CL with prostaglandin would you expect to see her bulling?

Answer 18

2-5 days

Question 19

How can you differentiate pregnancy from metritis / endometritis on ultrasound?

Answer 19

Foetal fluids - clear, anechoic, membranes and foetus, lining of endometritis well defined

Metritis / endometritis - slightly more hyperechoic, snow storm appearance, lining of endometrium poorly defined

Question 20

What would you expect on a vaginal exam for a cow in oestrus?

Answer 20

Bulling string

Open cervix

Question 21

How long after calving should you expect the first ovulation in a cow?

Answer 21

14-18d if no CL

Question 22

What would you expect the uterus to feel like in a 3 month pregnant cow?

Answer 22

Small cotyledons
Ballot a melon sized calf
Uterine artery pulse on pregnant horn

Question 23

At what stage can you palmate fremitus in the uterine artery?

Answer 23

5m pregnant horn

6m non-pregnant horn

Question 24

From how many days can you confidently scan for pregnancy?

Answer 24

28

Question 25

What are you looking for on a post natal check?

Answer 25

Endometritis Tears Return to cyclic activity Whether the cervix is open or closed

Question 26

When is the use of a PRID contraindicated?

Answer 26

Any infection of the reproductive tract | Causes vaginitis and local immunosuppression

Question 27

How soon after injecting a cow that has a CL with prostaglandin would you expect to see her bulling?

Answer 27

2-5 days

Question 28

How can you differentiate pregnancy from metritis / endometritis on ultrasound?

Answer 28

Foetal fluids - clear, anechoic, membranes and foetus, lining of endometritis well defined Metritis / endometritis - slightly more hyperechoic, snow storm appearance, lining of endometrium poorly defined

Question 29

What can lead to a reduced heat duration?

Answer 29

Lameness Low BCS High yield

Question 30

What factors can increase the calving to conception interval and no. inseminations per pregnancy?

Answer 30

``` Drop in social status Caesarean Bad calving Lameness Mastitis Milk fever - sub clinical hypocalcaemia has a huge effect on fertility Nutrition NEB at peak lactation Hepatic lipidosis ```

Question 31

What affect does lameness have on fertility?

Answer 31

Increases the calving to conception interval Increases the no. inseminations per cow Reduces pregnancy rate Later resumption of cyclicity, reduced oestrus intensity and oestrus related behaviours

Question 32

What is a repeat breeder?

Answer 32

A cow that has not conceived after 4 services

Question 33

What effect can milk yield have on the expression of oestrus behaviours?

Answer 33

High yielded may show fewer behavioural signs of oestrus

Question 34

What is the effect of the seasons on dairy cow fertility?

Answer 34

Poly-oestrus and non-seasonal However... - heat stress can reduce fertility in dairy cows in summer - poor quality silage fed in winter may reduce fertility