Principles of Fertility and Breeding Time Flashcards
What are the different methods of describing the nature of infertility? (4)
- Structural
- Functional – not cycling at the right time
- Management – e.g. identifying oestrous in cow, presenting dog to bitch at wrong time
- Infectious
When do you inseminate a dog?
3 days after ovulation
When do you inseminate a horse?
Day before ovulation
How can we determine optimal breeding time? (9)
•Observation of oestrous behaviour
–Standing e.g. a dairy herd will be obvious / lordosis / clitoral eversion
•Indirect methods of determining oestrous behaviour
–Reduced milk yield / increased activity
- Teasing with a male
- Observation of the external genitalia
–Swollen vulva / discharge from vulva
•Rectal palpation for ovarian structures
–Follicle size (remember species differences) / follicle tone
- Rectal palpation for cervical /uterine size or tone
- Ultrasound examination of follicular waves
–Follicle size / follicle softening / thickening of follicle wall / follicle haemorrhage
–Hard to U/S dog ovary – small in bursa and surrounded by fat
•Endocrine changes
–Low progesterone in most species / rising progesterone in the bitch
–Progesterone rises before oestrus in the dog but other animals will be after
•Assessment of endocrine changes by proxy assessments
–Vaginal cytology / vaginal wall endoscopy / vaginal fluid examination (crystallisation / pH etc)
Cow, how long is:
- Oestrus cycle?
- Luteal phase?
- Falling progesterone?
- Standing oestrus?
- 21 days
- 17 days
- 3 days proestrus
- around 1 day
In cows, when do the following occur:
- LH surge?
- Ovulation?
- Mid oestrus
- 24 hours after LH surhe (so 12 hours after end of oestrus)
Draw the model cow oestrus cycle
When do you mate a cow?
•Oestrus lasts up to 1 day, and ovulation occurs 12 hours after end of oestrus, thus
–Mating occurs ~1 day prior to ovulation
–Oocytes age if not fertilised and usually cannot be fertilised >24h after ovulation
When do you AI a cow?
–Semen survives the freezing process well
–Therefore uterine insemination normally undertaken 6-12 hours prior to ovulation
–i.e. same day oestrus has first been observed
In a ewe how long is:
- Osetrous cycle length?
- Duration of oestrus?
- Time of ovulation?
- 17 days
- 24-36hours
- 30-36 hours from beginning of oestrous
In a sow how long is:
- Osetrous cycle length?
- Duration of oestrus?
- Time of ovulation?
- 21 days
- 48-72 hours
- 35-45 hours from beginning of oestrus
In a mare how long is:
- Osetrous cycle length?
- Duration of oestrus?
- Time of ovulation?
- 21-23 days
- 4-8 days
- 1-2 days before end of oestrus
In a bitch how long is:
- Osetrous cycle length?
- Duration of oestrus?
- Time of ovulation?
- 210 days
- 7-14 days
- Variable- often 2 days after onset of standing oestrus
Why is the timing of insemination easy in the cow?
What is the problem?
Relatively easy since oestrus is short and tightly regulated to time of ovulation
Inseminate/mate at oestrus
Problem: detecting oestrus
What is the most common issue when getting a ewe up the duff?
Getting the correct ram:ewe ratio/identification of mated ewes
When do you AI a ewe?
insemination is slightly delayed (c.f. Cow): 12h after onset of oestrus
How do you AI a sow?
Mating and AI usually start on day 2 after the onset of standing oestrus.
2 inseminations
Why is mating the mare a problem? (2) how is this overcome?
The return of oestrus: variable
Oestrus length is variable
Normal practice is to tease daily and breed throughout this period, or to monitor ovaries with ultrasound
Why are bitches a problem for mating? (3) How can we judge it? (2)
Mono-oestrus
Oestrus very variable / very poorly indicate time of ovulation
Thus oestrus detection – poor tool for planning mating
Better tools: vaginal cytology and/or plasma progesterone measurement
What signs of oestrus are seen in cows and when?
What are the strategies to detect oestrus in cows? (3)
- Examine cows >4 times per day
- Detection aids e.g. Kamars, pedometers, Estrotect, GPS, electronic noses??
- Van Eerdenburg’s scoring
What can we measure to detect oestrus in the cow? (5)
Low plasma/milk progesterone
Detection of a large follicle (in absence of CL)
Others
- Crystallisation patterns in the vaginal mucus
- A fall in body temperature prior to oestrus
- A reduction in vaginal pH
What phase is this and how can you tell?
Luteal phase
CL and Medium Follicles
What phase is this and how can you tell?
(Pro)-oestrus Dominant Follicle (check both ovaries)
What factors might inhibit oestrous behaviour? (7)
–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 can we replace oestrus detecttion with in cows?
Synchronisation of ovulation e.g. Ovsynch
What are the signs of oestus in the ewe? (6)
•Restless
–Seeks the ram,
–Forms a following harem
•Stands for the ram
–waggles tail
–moves tail laterally to allow mating
•Vulva
–Slightly swollen
–Slight mucoid discharge
How can you detect oestus in the ewe? (4)
–Only important when AI regimes
–Vasectomised ram with raddle
–Synchronisation protocols
- Low plasma progesterone
What are the signs of oestrus in the sow? (7)
- 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
- 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
What are the signs of oestrus in the mare? (5)
- 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
How can you measure oestrus in the mare? (2)
- Detection of a large follicle (>20mm) in absence of a CL) (by palpation or ultrasound examination)
- Demonstration of follicle size, follicle wall thickening, follicle softening on ultrasound examination
What are the signs of proestrus in the bitch? (4)
–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? (4)
–Standing to be mated
–Deviation of tail
–Discharge becomes paler in colour
- Reduction in vulval oedema
How can we clinically assess oestrus detection in the bitch? (4)
- 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)
How long is proestus in the queen?
Short and often un noticed
What causes the LH response in the queen?
- Induced ovulator
- LH response to mating decreases with each day of oestrus and follicles ultimately regress
What are the signs of oestrus in the queen? (4)
- Increased vocalisation, rubbing and rolling
- Increased activity and will seek tom
- Possible slight mucoid vulval discharge
Stand to be mated by lowering her front quarters, extending her hindlegs and demonstrating lordosis – the tail is erect and held to one side
What is the difference between induced and spontaneous ovulators?
Induced ovulators:
–Presence of antral follicle and increased oestrogen still prerequisite for LH release and ovulation
–HOWEVER, copulation results in a neuro-endocrine response resulting in LH release and then ovulation
–Examples: cat, rabbit, ferret, mink, camelids
Spontaneous ovulators:
–Ovulation occurs at regular intervals
–Hormonally induced; driven by the antral follicle
What happens here? (4)
Inhibits oestrous behaviour (occasional exception in the mare)
Prepares uterus for pregnancy
Closes cervix
Blocks LH surge (not basal secretion)
What happens here? (4)
Stimulation development of antral follicles
Selection of dominant/ovulatory follicle(s)
= ↑ oestradiol = ↓ FSH – degeneration
↑ inhibin of subordinate follicles
What is happening here? (5)
uterine PGF2a
luteolysis
↓ progesterone
↑ oestradiol from ovulatory follicle
LH surge à next ovulation
What can cause anoestrus? (6)
- Gestation
- Lactation / presence of offspring; Note: species differences
- Seasonality
- Stress
–Metabolic
–Heat
•Ovarian pathologies
–Cystic ovarian disorders
–Inactive ovarian activity
•Monoestrous breeders
–e.g. bitches
What is a silent oestrus?
Ovulation with limited signs of oestrus
- Often at first oestrus after seasonal anoestrus / parturition
- No progesterone priming
- No progesterone fall
- No sudden release of oestrogen or LH suppression
