Non-infectious causes of reduced repro. performance cattle

Question 1

What are cysts or Gartner’s ducts?

Answer 1

Linear series of cysts located on floor of vagina
Remnant of Wolffian or mesonephric ducts in embryo
Don’t usually interfere with fertility

Question 2

What is a congenital vulvar wattle?

Answer 2

Resemble a rudimentary penis
No clinical significance
Can be attached to external skin of vulva or vestibular mucosa

Question 3

How can you differentiate a cow with a pyometra to one with mucometra or hydrometra?

Answer 3

Pyometra cows don’t usually cycle

Mucometra or hydrometra still will

Question 4

What is uterus unicornis?

Answer 4

Segmental aplasia of the paramesonephric ducts

• Can be fertile or infertile
• Can also have prolonged periods of dioestrus due to deficiency of PG

Question 5

What 4 things can cause vulval swelling?

Answer 5

Allergic reaction
Photosensitisation
Insect bites
Dystocia

Question 6

What is the most common vuvlal neoplasia?

Answer 6

Squamous cell carcinoma

Question 7

What can cause prolapse of the cervix?

Answer 7

Poor vestibular tone and abdominal pressure when the cow lies down

Question 8

What is the aetiology of freemartinism?

Answer 8

A male and female twin foestus results in placental fusion and vascular anastomosis
This exposes the female foetus to testosterone, anti-mullerian hormone and expression of the SRy gene when sexual differentiation is occuring, causing masculisation

Question 9

When does sexual differentiation occur in the cow?

Answer 9

Day 40

Question 10

What percentage of female foetuses with cotwinned male will be affected by freemartinism?

Answer 10

Over 90%

Question 11

What are some clinical signs of freemartinism?

Answer 11

Not pregnant after breeding period
Externally may see tuft of hair from ventral vulva labia 
Hypoplastic mammary teats
Prominent clitoris
Short vagina 
Hypoplastic reproductive tract

Question 12

How do you diagnose freemartinism?

Answer 12

History - Twin, infertile
Vaginal length 
Hypoplastic tract
Abnormal external appearance
Cytogenetic testing
PCR assay

Question 13

How do you manage freemartinism?

Answer 13

Cull

Or can be used as teasers if hormonally treated

Question 14

When are cows normally anoestrus?

Answer 14

early post partum

Question 15

How long typically is anoestrus?

Answer 15

20-40 days

Question 16

In a seasonal calving dairy herd, what percentage are often anoestrus at the start of the mating period?

Answer 16

15-30 %

Question 17

What effect does a suckling calf have on hormone secretion?

Answer 17

Reduced LH secretion

-Restricting suckling to less than 2 times a day can shorten the postpartum interval to first ovulation

Question 18

When and how should you detect anoestrus cows?

Answer 18

Before the mating season starts

Monitor for oestrus over 3-4 week periods

Question 19

What should you treat anoestrus cows with?

Answer 19

Progesterone for minimum 7 days

Question 20

How does progesterone treat anoestrus cows?

Answer 20

Helps reduce sensitivity of the hypothalamus to oestrogen negative feedback
Reduces incidence of short cycles following induction of ovulation

Question 21

If you are treating anovulatory anoestrus cows, do you need to include a PG injection after P4 device removal?

Answer 21

No

They won’t have a functional CL

Question 22

How long should the calving to mating interval be?

Answer 22

60-80 days

Question 23

What 3 things can significant BCS loss following calving cause?

Answer 23

Increase interval from calving to first ovulation
Decreased conception rates
Increased embryonic loss rates

Question 24

What has gradually happened to high producing dairy cows?

Answer 24

As milk yield increased there has been a decline in their reproductive performance
-Also shorter duration of oestrus
However fertility of maiden heifers has remained unchanged

Question 25

What are 4 consequences of a less favourable uterine environment?

Answer 25

Fewer embryos reach uterus following ovulation
Fewer embryos develop normally
Increased failure of maternal recognition of pregnancy
Increased embryonic mortality

Question 26

What is a phantom cow?

Answer 26

One that has been AI’d, doesn’t return to oestrus after 24 days and is also not pregnant

Question 27

What is the primary cause of phantom cows?

Answer 27

Early embryonic loss

Question 28

What is the thermoneutral zone for cattle?

Answer 28

23 - 27 degrees

Question 29

As internal core body temperatures rise, what effects does this have?

Answer 29

Adverse effect on physiological processes
Rumen function
Oocyte quality
Embryo viability

Question 30

What are some ways you can minimise consequences of heat stress on fertility?

Answer 30

Cooling cows - drench, don’t mist
Optimise nutrition to compensate reduced dry matter intake
Increased effort into heat detection
Use AI to reduce infertility with heat stressed bulls
Use cheaper semen since pregnancy rates likely to be lower
Breed more heifers in hot months
Genetic improvement
ET from cooler months - may not be economically viable
Used fixed time AI when heat detection is an issue

Question 31

When are cows most susceptible to heat stress having an effect on reproductive performance?

Answer 31

-1 to 6 days post service

Question 32

What are some reproductive consequences of severe negative energy balance?

Answer 32

Increased days to first ovulation
Decreased LH secretion
Decreased concentrations of IGF-I (reduces effectiveness of LH)
Delayed uterine involution
Decreased conception rates
Increased embryonic loss
Potential for later calving and shorter calving to breeding intervals next year

Question 33

What does a a diet with high rumen degradable nitrogen diet lead to?

Answer 33

Increased plasma concentrations of blood urea nitrogen

-Need time to adapt