Oestrus and its detection Flashcards
Explain the oestrus cycle in the cow
- 21 day oestrus cycle
- 17 day luteal phase
- Standing oestrus lasts approx. 1 day
- LH surge occurs mid oestrus and ovulation occurs 24 hours after this hence OVULATION=12H AFTER END OF OESTRUS
When should you mate a cow?
-Approximately 1 day prior to ovulation= this is when standing oestrus is occurring
Why are mares difficult to inseminate/ mate?
They have a long oestrus and the time of ovulation is long so timing it right is difficult.
- 4-8 days in oestrus and ovulation occurs 1-2 days before END of oestrus
- Usually try to manage with teasing daily with a teaser stallion or by ultraounding ovaries
Why are bitches difficult to inseminate/ mate?
- Because they are monoestrus, and they have a very long luteal phase follower by periods of anoestrus. In addition the time of ovulation is very varied
- Managed using vaginal cytology and/ or progesterone measurement
Describe oestrus behaviours exhibited by cows
- Standing heat
- Mounting
- Chin pressing
Describe aids available for detecting oestrus in cows
- Kamars (detect mounting)
- Pedometers (activity increases during oestrus)
- Estrotect
What is Van Eerdenburgs scoring?
Set amount of points given to each oestrus behaviour, when a cow has more than 50 points on the chart she should be served.
How can milk progesterone help detect oestrus?
-When milk progesterone drops you know she is in oestrus so you can serve her. Must be analysed throughout cycle.
Why must you check BOTH ovaries when ultrasounding a cow for oestrus detection?
-She may have a dominant follicle in one ovary but a CL in the other. The CL is dominant over the follicle so she will not be in oestrus.
What factors may inhibit oestrus behaviours?
Concrete floor High temperatures Overstocking Lameness Stress
Describe oestrus behaviours in the ewe
- Become restless: want to seek the ram, form a following harem.
- Stand for the ram and wiggle tail
- Vulva becomes swollen, slight mucousy discharge
Describe signs of oestrus in the sow
-Restlessness with grunting
-Pacing
-Reduced appetite
-Swollen vulva
0Increase in sexual behaviour
-Responsive to boar pheromones
What does ‘foal heat’ mean?
- Mares normally return oestrus 6-10 days after foaling.
- Foal normally develops diarrhoea at this time so it is easy to spot, but mare may not be very fertile during this oestrus
- ‘Foal shy’ is when a mare has an older foal underfoot and is protective of the foal so doesn’t show signs of oestrus
What are the signs of oestrus in the mare?
- Swollen vulva
- Holds tail high and leans her hindquarters towards stallion
- ‘Winking’ of clitoris
- Induces ‘flehmen’ response in stallion
What are the clinical assessment methods of oestrus detection in mares?
- Ultrasound of ovaries(large follicle, thickened follicle wall, follicle may start to involute)
- Palpation of ovaries
Describe oestrus behaviour in the queen
- Proestrus is short and often unnoticed
- Increased vocalisation, rubbing, rolling
- Increase activity and will seek tom cats
- She stands to be mated by lowering front quarters, extending hindlegs and exhibiting lordosis, tail held to one side
In induced ovulators, what response results in the LH release and ovulation?
Neuro-endocrine
What impact does progesterone have on oestrus?
- Inhibits LH surge
- Closes cervix
- Inhibits oestrus behaviour
What can cause periods of anoestrus to occur?
- Gestation
- Lactation (presence of offspring)
- Seasonality
- Stress
- Ovarian pathologies: cysts
- Monoestrous breeders
What is a silent oestrus, which species is it a problem in?
- Ovulation with limited signs of oestrus
- Often occurs at first oestrus after parturition
- It is a problem in cows
