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Reproduction > Fertility, Subfertility and Infertility in the Cow > Flashcards

Fertility, Subfertility and Infertility in the Cow Flashcards

1
Q

What is a subfertile cow?

A

One that fails to achieve its fertility target, or that of the herd or group.

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2
Q

What is an infertile cow?

A

Incapable of becoming pregnant regardless of how long she is given to achieve pregnancy

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3
Q

How do yield and successful AI% correlate?

A

Yield is negatively correlated with first AI pregnancy %

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4
Q

What are the 4 causes of subfertility in cattle?

A

Structural causes
Functional causes
Management causes
Infectious agents

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5
Q

What are the major signs of subfertility in cattle?

A

No observed oestrus
Regular or irregular returns to oestrus
Presence of abnormal vulval discharge
Abortion and stillbirth

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6
Q

When is it normal to not observe an oestrus?

A 
Pregnancy
Immediately postpartum (4-6wks)
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7
Q

What are possible reasons for no observed oestrus?

A

In heifers congential issues
Acyclical or anoestrus
Ovarian cycsts
Cyclical ovarian activity is occuring but heat detection suboptimal
Cyclical activity occurring but limited behaviour

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8
Q

What is the genetic basis of ovarian aplasia and hypoplasia?

A

Autosomal recessive gene with incomplete penetrance

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9
Q

How can you diagnose freemartinism?

A

Test tube or thermometer case - put into vagina will only enter 2-3cm if freemartin
Karyotyping

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10
Q

Why does freemartinism occur?

A

Blood vessels in the chorion of twin foetuses become fused and interconnected, creating a shared circulation. The male foetus produces male hormones (testosterone and anti-mullerian hormone) and these are introduced to the circulation of the female foetus causing masculinisation of the female.

The effects of the fusion are seen more greatly when it occurs early on in pregnancy.

Freemartinism only occurs in male/female twins, not female/female.

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11
Q

What can cause there to be no observed oestrus in the cow?

A 
Anoestrus or true acyclicity
Cystic ovarian disease
Persistent CL
Pyometra with persistent CL
Sub-oestrus
Failure to detect oestrus
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12
Q

What causes anoestus or true acyclicity in the cow?

A 
High milks yields
Inadequate feeding, particularly energy
Poor body condition
- may reflect poor nutrition or disease
Stress
- lameness
-- discomfort
--- interferes with feeding pattern
intercurrent disease
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13
Q

What will you find on clinical examination of a cow in anoestrus, or with true acyclicity?

A

Rectal examination shows involuted tract; ovaries feel small, smooth and flat

US shows follicles <1.5cm with no CL

Milk progesterone will be low @ 10 day intervals

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14
Q

How does freemartinism affect the female reproductive tract?

A

The heifer’s reproductive tract is severely underdeveloped and sometimes even contains some elements of a bull’s reproductive tract.

The ovaries of the freemartin do not develop correctly, and they remain very small. Also, the ovaries of a freemartin do not produce the hormones necessary to induce the behavioral signs of heat. The external vulvar region can range from a very normal looking female to a female that appears to be male. Usually, the vulva is normal except that in some animals an enlarged clitoris and large tufts of vulvar hair exist.

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15
Q

How does inadequate nutrition influence fertility through reduced IGF-1 production?

A

Hypothalamus

  • reduced GnRH secretion
  • reduced + feedback to oestrus

Pituitary

  • reduced LH and FSH secretion
  • reduced response to GnRH

Ovary

  • decreased granulosa proliferation and differentiation
  • decreased LH/FSH supported steroidogenesis
  • reduced aromatase activity
  • reduced luteal activity and steroidogenesis

Embryo

  • decreased embryo growth
  • reduced IFN production
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16
Q

How can you treat aneostrus or true acyclicity in cattle?

A

Wait until milk yield falls, or cow returns to positive energy balance

Hormonal
GnRH
Progesterone such as PRID
PRID alone or with GnRH

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17
Q

What are the normal fluid filled structure in bovine ovaries?

A

Follicles
1.5-2.0cm diameter during oestrus
<1.5cm diameter rest of cycle

Vaculoated CL
Same size as non-vaculoated CL
Disppears during pregnancy
Usually single

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18
Q

What are abnormal fluid filled structure on the bovine ovaries?

A

Luteinised follicles
<2.5cm diameter, no sign of ovulation larger cavity than vacuolated CL

Follicular and inactive cysts
Soft, thin walled (<3mm) fluid filled structure >2.5cm diameter. Low P4.

Luteal cysts
Thick walled (>3mm) fluid filled structure >2.4cm in diameter. High P4.
19
Q

What are ovarian cysts and how are they formed?

A

Fluid filled structures on the ovaries over 2.5cm in diameter. They persist for longer than 10 days.

Develop from anovulatory graafian follicles which fail to ovulate or regress

20
Q

What are the 3 types of ovarian cysts?

A

Thin walled, oestradiol secreting follicular cysts

Thick walled, progesterone secreting luteal cysts

Thin walled, functionally undifferentiated inactive cyst

21
Q

Which is the most common type of cyst?

A

Inactive

22
Q

Why does normal ovulation occur?

A

Ovulation of the dominant follicle is due to LH surge induced by increased secretion of oestradiol by the mature dominant follicle

23
Q

How do thick walled luteal or luteinised cyst result in acyclicity?

A

Negative feedback of P4 on anterior pituitary

24
Q

What can lead a failure of LH surge?

A

After calving there is a progressive restoration of the ability of the hypothalamus to respond to oestradiol to produce an LH surge.

Failure of oestradiol to elicit a normal + feedback stimulation of LH surge

25
Q

What are the ovarian causes of cysts?

A

Reduced number of LH receptors in granulosa cells

Low insulin and IGF-1 and NEB causing >NEFAs which impairs follicular proliferation and function

26
Q

Why should you not rupture ovarian cysts transrectally?

A

Can cause damage to other structure of the ovaries, such as adhesions. These may negatively impact fertility.

27
Q

How should you treat a luteal cyst?

A

PGF2-alpha - regress CL

28
Q

How should you treat a follicular cyst?

A

GnRH or hCG to cause luteinisation, followed by PGF2-alpha or PRID/CIDR for 10-12 days

29
Q

How does pyrometra lead to CL persistence?

A

Pathological changes in the uterus interfere with luteolysin production and the CL persists, which perpetuates the disease. Treat with PGF2-alpha

30
Q

What are the signs of oestrus in the cow?

A 
Restless, not eating, drop in milk yield
Searches for other cows, mounting
Bellowing
Clear vulval elastic mucous discharge
Head mouting
Standing to be mounted
31
Q

What is the most important sign of oestrus?

A

Standing to be mounted

32
Q

Why may oestrus not be detected?

A

Cow problem:
Duration of oestrus may be short and signs may be covert

Person problem:
Due to poor facilities for cows to express behaviour and a poor observational regimen

33
Q

How often should you examine cows for oestrus?

A

20-30mins at least 3 times per day, other than milking

Use other methods

34
Q

What are the methods for modifying normal ovarian cyclical activity to implement fixed time AI in cattle?

A

2 injections of PGF2-alpha 11 days apart with a single AI @ 72-84 hours after 2nd injec. OR double AI @ 72 and 96hrs

Insert PRID or CIDR for 7-9days with PGF2-alpha injected 24 hoyrs before removal and double dixed time AI @ 48 and 72 hours or single @ 56 hours

35
Q

What are the possible reasons for a cow not calving after service or AI?

A

Oocytes not fertilised
10-15%

Embryo death before 13 days
15-20%

Embryo dies between 13-42 days
10%

Foetal death after 42 days
5%

36
Q

What are the causes of fertilisation failures that are not due to bull or poor semen?

A 
Anovulation
Delayed ovulation
Incorrect AI timing
Serving too early postpartum
(6weeks to involute)
Hormonal imbalances
Structual defects 
Infection of genital tract
Stress
Nutritional
37
Q

What are the possible causes of early and late embryonic death?

A 
Luteal deficiency and hormonal imbalance
Uterine infection with specific embryopathic micro-organism
Infection with opportunistic pathogens
Genetics
Heat or other stress
Nutritional
38
Q

What are some embryopathic microganisms?

A 
Campylobacter fetus
Tritrichomonas fetus
Mycoplasma, ureaplasma
BVDV
IBR
Bluetongue
Chlamydophila psittaci
39
Q

What is a repeat breeder cow?

A

A cow that has returned to oestrus after AI or natural service on 3-4 consecutive occasions

40
Q

What are some good approaches to treating the repeat breeder cow?

A

Change sire

Use semen from good bulls

Inseminate at normal time and 24hr later

hCG or GnRH at time of first AI to stimulate a second ovulation to produce an accessory CL to increase progesterone

11-12 days post AI, GnRH IM to enhance CL

11-12 days frollowing AI consider the use of PRID or CIDR

41
Q

How does uterine infection affect fertility?

A

Direct pathology on gamete, embryo, foetus

Innate immune signal response in endometrium

Alters endocrine signalling

  • CL development
  • HPA axis

Influences ovarian function, notably follicular and oocyte development

42
Q

What are the predisposing factors for endometritis?

A 
Longer or shorter gestation
RFM
Parity
Milk yield
Dystocia and trauma
Hygiene
Season of year
Intercurrent disease
Nutrtional
43
Q

What should you check when you look at the vaginal contents when endometritis is present/

A

Volume
Smell
Colour

44
Q

What are the non-infectious causes of abortion or stillbirth in cattle?

A 
Genetic factors e.g. abnormalities
Endocrine deficiencies and excesses
Toxic substanes
Heat stress
Misuse of therapeutics 
Stillbirth: dystocia

Reproduction (22 decks)

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