Principles of Breeding and Fertility Flashcards
How long is the cow oestrus cycle?
21 days
How long is the luteal phase in the cow
17 days
When does the LH surge occur in the cow?
Mid oestrus
When does ovulation occur in the cow oestrus cycle?
12 hours after the end of oestrus
How long does oestrus last in the cow?
5-18hours
When does mating occur in the cow?
1 day prior to ovulation
When does AI occur in the cow?
6-12hours prior to ovulation, same day oestrus has been observed
How long is the ewe oestrus cycle?
17 days
How long does oestrus last in the ewe?
24-36h
When does ovulation occur in the ewe?
30-36hours from beginning of oestrus
How long is the oestrus cycle in the sow?
21 days
How long does oestrus last in the sow?
48-72h
When does ovulation occur in the sow?
35-45hours from begining of oestrus
How long is the oestrus cycle in the mare?
21-23days
How long does oestrus last in the mare?
4-8 days
When does ovulation occur in the mare?
1-2 days before end of oestrus
How long is the oestrus cycle in the bitch?
210 days
How long does oestrus last in the bitch?
7-14days
When does ovulation occur in the bitch?
Variable- often 2 days after onset of standing oestrus
What is the timing of insemination/mating in the cow?
Inseminate/mate at oestrus.
Relatively easy since oestrus is short and tightly regulated to time of ovulation
The problem is detecting oestrus.
What is the timing of insemination/mating in the ewe?
AI: insemination is slightly delayed in comparison to the cow. 12h after onset of oestrus.
What is the key issue when mating/insemination ewes?
Correct ram:ewe ratio/ identification of mated ewes
What is the timing of insemination/mating in the sow?
Mating and AI usually start on day 2 after the onset of standing oestrus.
2 inseminations
What is the timing of insemination/mating in the mare?
Mares are a problem! Return of oestrus is variable. Oestrus cycle variable. Normal practice is to tease daily and breed throughout this period or to monitor ovaries with u/s
What is the timing of insemination/mating in the bitch?
Bitches are a problem!
Mono-oestrus
Oestrus very variable / very poorly indicate time of ovulation
Thus oestrus detection – poor tool for planning mating
What are better tools to plan for mating in the bitch?
vaginal cytology and/or plasma progesterone measurement
What are some of oestrus behaviours carried out by the cow?
Swelling of vulva, mucous discharge Chin pressing Reduced milk yield Brawling, restless Mounts other cows Stands to be mounted Bloody discharge occurs after the end of oestrus.
What are some of the strategies for detecting oestrus in the cow?
Examine cows >4 times per day
Detection aids e.g. Kamars, pedometers, Estrotect, GPS, electronic noses??
Van Eerdenburg’s scoring
What are some of the clinical assessment/measurements that can be carried out to detect oestrus in the cow?
Low plasma/milk progesterone
Detection of a large follicle (in absence of CL)
Other methods include: crystallisation patterns in the vaginal mucus, a fall in body temperature prior to oestrus and a reduction in vaginal pH
What factors might inhibit oestrus behaviour?
Hard, non-supportive floor is best Concrete reduces oestrous behaviour by up to 50% especially when wet and slippery High environmental temperature Overcrowding Recent mixing / stress Lameness FEEDING
What are some detection methods/aids in detecting oestrus in the ewe?
Only important when AI regimes.
Vasectomised ram with raddle.
Synchronisation protocols.
Low plasma progesterone.
What are the signs of oestrus in the dow?
Vulval swollen and congested prior to oestrus
Seeks the boar
Stands firmly to be mounted (the back pressure test; very reliable)
Stands for a smelly old boar that produces lots of saliva
Other signs: Restlessness with repetitive grunts Pacing and searching Lowered feed intake and loss of appetite Red, swollen vulva Male-like sexual behaviour Increase in vaginal mucus Response to boar pheromones
Whare are the signs of oestrus in the mare?
Vulva: Oedema / mucoid discharge
Elevated tail and lean her hindquarters towards the stallion
“winking” (repeated exposure of clitoris)
Induces “flehmen” response in stallion
Commonly, daily teasing is performed
What are the clinical assessments/measurements that can be carried to detect oestrus in the mare?
Detection of a large follicle (>20mm) in absence of a CL - by palpation or u/s
Demonstration of follicle size, follicle wall thickening, follicle softening on u/s exam.
What are the signs of proestrus in the bitch?
Very long (classically 9 days)
Bitch is attractive but not allow mating
Vulval swelling
Presence of a serosanguinous discharge
What are the signs of oestrus in the bitch?
Standing to be mated
Deviation of tail
Discharge becomes paler in colour
Reduction in vulval oedema
What clinical assessments can be carried out in the bitch to detect oestrus?
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)
What kind of ovulator is the queen?
Induced
What are the signs of oestrus in the queen?
Increased vocalisation, rubbing and rolling
Increased activity and will seek tom
Possible slight mucoid vulval discharge
How is ovulated induced in the queen?
Copulation results in a neuro-endocrine response resulting in LH release and then ovulation.
The presence of an antral follicle and increased oestrogen is still a prerequiste for LH release and ovulation.
What are some examples of induced ovulators?
Cat, rabbit, ferret, mink, camelids
What are some examples of induced ovulators?
Cat, rabbit, ferret, mink, camelids
What occurs during dioestrus?
1) Stimulation development of antral follicles and selection of dominant/ ovulatory follicles.
2) Get an increase in oestradiol which leads to decreased FSH resulting in degeneration of subordinate follicles
Also get an increase in inhibin.
What occurs during (pro)oestrus?
Non pregnant: Uterine PGF2a resulting in luteolysis, decreased progesterone, increased oestradiol from ovulatory follicle and an LH surge
What are some of the causes for anoestrus?
Gestation
Lactation/ presence of offspring - foal shy
Seasonality
Stress (metabolic and heat)
Ovarian pathologies (cystic ovarian disorders, inactive ovarian activity)
Monoestrus breeders (bitches)
What is a silent oestrus
Ovulation with limited signs of oestrus
When does the silent oestrus occur?
Often at first oestrus after seasonal anoestrus/parturition
Why does a silent oestrus occur mostly at the first oestrus after seasonal anoestrus/ parturition?
No progesterone priming
No progesterone fall
No sudden release of oestrogen or LH suppression
