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Repro > Bovine > Flashcards

Bovine Flashcards

1
Q

Is a cow who is mounting another, or the one being mounted, more likely to be in estrus?

A

The one standing to be mounted. The one mounting may of may not be in estrus.

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2
Q

List 10 factors that can affect the expression of oestrous behaviour in cows.

A
  • Number of cows simultaneously in oestrus
  • Environment -> slippery surfaces or reduced interaction between cows may reduce sexual behaviour
  • Stress
  • Lameness
  • Moving of animals
  • Climate
  • Health
  • Nutrition and milk yield / negative energy balance
  • Age
  • Breed
  • Synchronization method
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3
Q

A “Kamar” device is:

a) A device used to correct uterine torsion in cows.
b) a rump mounted device that is used as an aid for the detection of oestrus.
c) a device that attaches to the leg of cows and monitors the walking activity of cows.
d) a device that measures the electrical impedenceof vaginal secretions of cows.
e) a bench mounted machine that can be used to measure concentrations of progesterone in milk or serum.

A

b) a rump mounted device that is used as an aid for the detection of oestrus.

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4
Q

What is the recommended percentage of eligible cows that should be submitted for AI within 3 weeks of the start of mating?

A

> 85%

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5
Q

Outline some of the potential causes for low submission rates to AI in the first 3 weeks of the breeding season.

A

High proportion of non-cycling cows or poor oestrus detection

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6
Q

If you were to make some recommendations to improve submission rates how would you check to see if any improvements in submission rates occurred and how might you determine if the cows that are being submitted for AI are actually in oestrus?

A

Review submission rates to see if improve, use submission rates vs pregnancy rates to assess if those submitted are truly in estrus

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7
Q

List secondary signs that are associated with oestrus in cows.

A 
Attempting to mount other cows
Mounting without standing
disorientated mounting
vulval mucus discharge
vulval swelling/oedema
restlessness
SAGs
Sniffing
Licking
Rubbing
Aggressive behaviour
Butting
Flehmen response
Bellowing
Chin resting
Walking further
Poor milk let down
Rubbed pin bones/base of tail
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8
Q

What ratio of teaser animal to cows would you recommend for a herd of 100 beef cows which have synchronised oestrous cycles?

A

1:10 - 1:30

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9
Q

What ratio of teaser animal to cows would you recommend for a herd of 100 beef cows which have unsynchronised oestrous cycles?

A

1:30 - 1:50

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10
Q

List 4 advantages and disadvantages associated with the use of AI

A

Adv - Improved genetic progress, disease control, wider sire choice, safety, improves record keeping
Dis - Cost, requires good management, skills and facilities, may spread undesirable traits unintentionally and may reduce pregnancy rates

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11
Q

What is the difference between the non-return rate and pregnancy rate?

A

Pregnancy rate is the % of cows diagnosed as pregnant (out of herd or out of those inseminated) while non-return rate is the % of cows not detected in estrus following insemination

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12
Q

Should non-return rate be higher or lower than pregnancy rates?

A

Higher

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13
Q

When would you consider using non-return rate data rather than pregnancy rate data?

A

When pregnancy rate data may not be available

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14
Q

What is the definition of the term, “6-week in-calf rate”?

A

% of cows that are diagnosed as being pregnant in the first 6w of the breeding season.

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15
Q

The correct site for the deposition of semen into the reproductive tract of cows using artificial insemination in order to obtain optimal pregnancy rates is…

A

The uterine body

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16
Q

What is the impact on fertility of inserting the insemination gun too far through the internal os of the cervix when inseminating cows in terms of pregnancy rates. Explain your reasoning.

A

The gun may enter into one horn, which may be the horn that does not hold the ovum. This results in reduced pregnancy rates.

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17
Q

What are some of the potential risks for using custom collected semen compared to semen processed within a licensed breeding centre.

A

No guarantee of quality or disease status

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18
Q

List 5 diseases that could potentially be transmitted in bovine semen.

A

Bovine emphemeral fever, Tuberculosis, Johne’s disease, Q fever, Blue tongue, Brucellosis

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19
Q

Outline the general steps that are undertaken when processing and freezing bovine semen.

A

Semen collection -> semen evaluation -> extended (glycerol free) -> cool slowly to 4 degrees -> Add glycerol extender and leave for 4h -> package into straws -> freeze

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20
Q

How many sperm cells on average would be collected from a single ejaculate from a bull and how many doses of frozen semen could be processed from this?

A

1/2 to 4 billion sperm (or higher) giving 20 - 200 doses (or more) of 20-25 million sperm

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21
Q

Splitting straws: many dairy farmers will split a straw of semen between two cows to reduce insemination costs. What is the risk associated with this practice based on what you know about the effect of dose on pregnancy rates?

A

The straws may have been filled to give the correct dose, halving it gives less then the optimum dose and a decrease in pregnancy rates can be expected.

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22
Q

What is the optimum time for insemination of cows following the onset of oestrus?

A

4 - 14 h after the onset of oestrus

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23
Q

What can happen if you inseminate cows too early or too late following the onset of oestrus?

A

Too early - sperm quality deteriorates before insemination can take place, low pregnancy rates
Too late - ovum aged, low embryo quality, low pregnancy rates

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24
Q

What recommendation would you make to farmers in relation to when they should inseminate their cows following detection of oestrus?

A

When onset of oestrus is not know accurately, cows should be inseminated when detected in oestrus. If it oestrus is know accurately then AI 4-14 h post onset of oestrus

25
Q

Outline the recommended thawing technique for bovine semen

A

Thawing should happen in a sheltered, clean, dry, warm environment away from direct sunlight using a water bath at 32-38 degrees for 30-60s. The interval between removing the straw from the nitrogen and AI should be less than 15 minutes.

26
Q

How soon should a frozen-thawed dose of semen be used after thawing?

A

Less than 15 minutes

27
Q

What is the temperature of semen stored within liquid nitrogen?

A

Less than -100 degrees C

28
Q

Outline the factors that can affect pregnancy rates to artificial insemination.

A

Low quality semen, poor handling techniques, poor processing, poor AI technique, inadequate storage, disease, poor AI timing, poor cow fertility, poor nutrition or heat stress, etc.

29
Q

You analyse a herds reproductive performance and calculate that first service conception rates were 28%, which is lower than you expect in this herd. Outline your approach to trying to determine the cause of low conception rates.

A

Gain a thorough history, check submission rates, ask about how they detect oestrus and when they inseminate in relation to detecting estrus. Assess sperm quality, nutritional status of cows. Ask about where they are getting their sperm and who deposits it into the cow. How long is it out of the nitrogen, how do the defrost it. Check for disease.

30
Q

Once a dose of frozen semen is thawed and loaded within an AI gun it is recommended that it be deposited within the uterus of a cow within

A

15 minutes

31
Q

What precautions should you observe when using prostaglandin F2α or its synthetic analogues to synchronise oestrus in cattle?

A

Wear gloves and wash off an spilled on skin, ensure pregnant women do not use. Ensure cows could not be pregnant. Causes abortions in humans and cattle, plus respiratory difficulty.

32
Q

At what stage of the cycle is an injection of PGF2α most likely to cause luteolysis in cows and in heifers?

A

Diestrus (> 5 days post ovulation)

33
Q

What percentage of cows in a randomly cycling group of cows would you expect to enter oestrus after a single injection of PGF2α?

A

~ 60%

34
Q

Explain how two injections of prostaglandin F2α administered 14 days apart can be used to synchronise oestrus in cattle. What are the advantages of this protocol and what are its limitations?

A

~60% of cows will respond to the first shot of PGF2a, will ovulate and have a CL of over 5 days by the second injection and hence ovulate over the next 5-7 days. the ~40% that did not respond to the first PGF2a shot because they did not have a CL or it was too immature, will have a mature CL by the second injection and hence also come into withing heat 5-7 days.

35
Q

Explain the physiological reason for the variation in the interval to oestrus following the administration of prostaglandin F2α to cattle.

A

This program does not synchronise follicular development

36
Q

What might be some reasons that some cows injected with prostaglandin F2α fail to be detected in oestrus within 7 days of treatment?

A

They may not have a mature CL, or may be in anoestrus or be in heat but not showing.

37
Q

Explain how a single shot prostaglandin protocol could be used to reduce the number of days of heat detection from 3 weeks to 12 days associated with an AI program

A

With randomly cycling cattle, you have to heat detect all 21 days of their cycle. With a single shot of PGF2a, 60% of those will have a CL older than 5 days old and respond by being in estrus withing the next 7 days. The 40% that didn’t respond should have been in estrus in the 5 days before the injection. Hence heat detection can be reduced to 12 days instead of 21

38
Q

What hormone does a Cue-mate release and how long would you leave it in for to synchronise estrus?

A

Progesterone, 7-8 days

39
Q

Can a Cue-mate be reused?

A

May be reused once. Disinfection is best done by autoclave but is often not practical. Alternatively, submerge in water on removal, pressure hose and rinse to remove mucous, soak in disinfectant (Virkon or Sodium hupochlorite), rinse in clean water, dry and place in sealed container/plastic bag

40
Q

You suspect that a cow is a freemartin. How could you confirm your diagnosis and what is the physiological cause of this condition?

A

Diagnosis can be made on the history of having a male twin and being infertile, as well as clinical signs. Cytogenetic testing or PCR can also be done. It is caused by exposure of a female twin to her male twin’s testosterone and anti-mullerian hormone at the time of sexual differentiation.

41
Q

Cows affected by cystic ovarian disease commonly display which one of the following clinical signs?

a. Anoestrus
b. Nervous signs such as aggression
c. Regular onset of oestrus without ovulation about every 21 days
d. Have ovarian follicles 15 to 20 mm in diameter

A

a. Anoestrus

42
Q

Define what is meant by the term cystic ovarian disease and how it can reduce reproductive performance in herds.

A

The presence on one or more ovaries of a follicle >25mm in diameter in the absence of a CL causing anovulation and anoestrus hence a decrease in conception

43
Q

Outline how cows with cystic follicles may be treated.

A

With no treatment most cases less than 45 days post partum will spontaneously resolve. Can rupture or aspirate but this increases risk of adhesions. PGF2a may be used if luteinisation has occur but it can be difficult to tell, hence induction of the LH surge independent of the hypothalamus by GnRH or hCG can be used to induce ovulation or luteinisation. In chronic cases the HPA may have become insensitive to oestradiol and progesterone treatment may be needed.

44
Q

Which one of the following hormonal treatments is used to treat cystic ovarian disease?

a) GnRH
b) eCG (equine chorionic gonadotrophin)
c) Oestradiol benzoate
d) Follicle stimulating hormone
e) Cortisone

A

a) GnRH

45
Q

Explain the difference between ovulatory and anovulatory anoestrous.

A

Ovulatory anoestrous - ovulation occurs but the cow does not show signs of heat.
Anovulatory anoestrus - no ovulation and no signs

46
Q

Outline some of the causes of anoestrous in cows.

A 
Ovarian quiescence
- Nutritional and BCS
- Negative energy balance
- Suckling
- Disease
- Ovarian tumors
- Cystic ovarian disease
- Age
- developmental defect
Behavioural (silent heat)
Prolonged luteal function
- Pyometra
- Pregnancy
- Early embryonic loss
Inadequate heat detection
47
Q

What is the physiological mechanism(s) by which suckling can prolong the postpartum period of anoestrus?

A

Suckling reduces the amplitude and pulse frequency of blood LH

48
Q

Outline management strategies that can be used to reduce the percentage of anoestrous cows at the start of mating in a dairy herd

A

detect anoestrous cows early by monitoring for a 3-4 week period before the start of the breeding season. Optimise BCS at calving and provide proper nutrition. Calve heifers down earlier than the main herd, giving them more time to commence cycling before mating. Genetic selection for shorter postpartum anoestrus intervals.

49
Q

What percentage of dairy cows are often anoestrous at the start of mating in a seasonally calving dairy herd?

A

15 - 30%

50
Q

Describe management strategies that can be used in beef heifers to reduce postpartum anoestous intervals following their first calving.

A

Optimise nutrition and BCS at calving (>4.5%). Wean early, restrictive suckling. Genetic selection for shorter postpartum anoestrus intervals. Calve heifers down early, before main herd.

51
Q

Discuss the effects of loss of body condition post calving on fertility in cows.

A

A loss of body condition shows a greater negative energy balance and hence a lower conception rate and increased anoestrus intervals and embrionic losses.

52
Q

What is the recommended minimal loss of body condition in dairy cows that is recommended post calving using a 1 to 8 scoring system.

A

0.45

53
Q

Outline the target body condition scores for dairy cows at the time of calving.

A

Less than 5% that are less than bcs 4.5/8

54
Q

How could you increase the percentage of cows within a seasonal calving dairy herd that have a calving interval of 40 to 80 days at the start of mating?

A

Calve down earlier by calving induction of late calving cows, synchronisation of estrus so more cows conceive at the start of the breeding season, selective culling of late culling cows and replace with early calving heifers

55
Q

Describe how conception rates are affected by calving to mating interval in cows.

A

Fertility improves with increasing interval post calving but is usually optimal by 60-80 days

56
Q

Explain why managing the live weights of heifers is critical for optimising pregnancy rates in maiden heifers.

A

Heifer’s in poor body condition at mating may not be cycling or have a reduced fertility.

57
Q

How does the liveweights of maiden heifers affect their lifetime productivity?

A

Heifers in poor body condition produce less milk and take longer to cycle post calving which delays conception. This late conception makes the first calf heifers at greater risk of culling, calving induction and shorter lactations. They also calve less easily.

58
Q

What management strategies could you use in beef heifers to improve reproductive performance?

A

Optimise nutrition and BCS at breeding. Mate more heifers than will be needed as replacements by at least 25% to allow good selection from pregnant animals - select those that got pregnant the earliest.

59
Q

What ratio of bulls/100 heifers would you recommend for a dairy farmer who is mating 100 Holstein-Friesian heifers to Jersey bulls?

A

4, assuming that no synchronisation of estrus has taken place and none are already pregnant.

Repro (2 decks)

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