Non-infectious causes of reduced repro. performance cattle Flashcards
What are cysts or Gartner’s ducts?
Linear series of cysts located on floor of vagina
Remnant of Wolffian or mesonephric ducts in embryo
Don’t usually interfere with fertility
What is a congenital vulvar wattle?
Resemble a rudimentary penis
No clinical significance
Can be attached to external skin of vulva or vestibular mucosa
How can you differentiate a cow with a pyometra to one with mucometra or hydrometra?
Pyometra cows don’t usually cycle
Mucometra or hydrometra still will
What is uterus unicornis?
Segmental aplasia of the paramesonephric ducts
- Can be fertile or infertile
- Can also have prolonged periods of dioestrus due to deficiency of PG
What 4 things can cause vulval swelling?
Allergic reaction
Photosensitisation
Insect bites
Dystocia
What is the most common vuvlal neoplasia?
Squamous cell carcinoma
What can cause prolapse of the cervix?
Poor vestibular tone and abdominal pressure when the cow lies down
What is the aetiology of freemartinism?
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
When does sexual differentiation occur in the cow?
Day 40
What percentage of female foetuses with cotwinned male will be affected by freemartinism?
Over 90%
What are some clinical signs of freemartinism?
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
How do you diagnose freemartinism?
History - Twin, infertile Vaginal length Hypoplastic tract Abnormal external appearance Cytogenetic testing PCR assay
How do you manage freemartinism?
Cull
Or can be used as teasers if hormonally treated
When are cows normally anoestrus?
early post partum
How long typically is anoestrus?
20-40 days
In a seasonal calving dairy herd, what percentage are often anoestrus at the start of the mating period?
15-30 %
What effect does a suckling calf have on hormone secretion?
Reduced LH secretion
-Restricting suckling to less than 2 times a day can shorten the postpartum interval to first ovulation
When and how should you detect anoestrus cows?
Before the mating season starts
Monitor for oestrus over 3-4 week periods
What should you treat anoestrus cows with?
Progesterone for minimum 7 days
How does progesterone treat anoestrus cows?
Helps reduce sensitivity of the hypothalamus to oestrogen negative feedback
Reduces incidence of short cycles following induction of ovulation
If you are treating anovulatory anoestrus cows, do you need to include a PG injection after P4 device removal?
No
They won’t have a functional CL
How long should the calving to mating interval be?
60-80 days
What 3 things can significant BCS loss following calving cause?
Increase interval from calving to first ovulation
Decreased conception rates
Increased embryonic loss rates
What has gradually happened to high producing dairy cows?
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
What are 4 consequences of a less favourable uterine environment?
Fewer embryos reach uterus following ovulation
Fewer embryos develop normally
Increased failure of maternal recognition of pregnancy
Increased embryonic mortality
What is a phantom cow?
One that has been AI’d, doesn’t return to oestrus after 24 days and is also not pregnant
What is the primary cause of phantom cows?
Early embryonic loss
What is the thermoneutral zone for cattle?
23 - 27 degrees
As internal core body temperatures rise, what effects does this have?
Adverse effect on physiological processes
Rumen function
Oocyte quality
Embryo viability
What are some ways you can minimise consequences of heat stress on fertility?
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
When are cows most susceptible to heat stress having an effect on reproductive performance?
-1 to 6 days post service
What are some reproductive consequences of severe negative energy balance?
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
What does a a diet with high rumen degradable nitrogen diet lead to?
Increased plasma concentrations of blood urea nitrogen
-Need time to adapt
