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Reproduction > Cattle Infertility 1 + 2 > Flashcards

Cattle Infertility 1 + 2 Flashcards

1
Q

Define infertile, subfertile and fertile cows.

A
  • infertile may = sterile or subfertile
  • subfertile fails to acheive the fertility target of the farm/herd/group
  • fertile meet fertility criteria eg. 13month calving interval or calving within tight seasonal limits
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2
Q

Is the fertility of cows changing?

A

Yes

- ^ milk yield correlates with v fertility

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3
Q

What are the 4 traditional cuases of sub-fertility in caltle?

A
  • structural
  • fucntional
  • management
  • infectious
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4
Q

What are the usual presenting 4 clinical signs of sub-fertility?

A
  • no observed oestrus
  • regular/irregular returns to oestrus after natural service/AI
  • Presence of abnormal vulval discharge
  • abortion and stillbirth
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5
Q

Why may some heifers never reach puberty?

A
  • congential abnormaltities
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6
Q

Once puberty has been reached, how frequently will she come into oestrus? What are the exceptions to this?

A
  • 18-24d

- unless pregnant or 4-6 weeks post partum

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7
Q

What is the most common cause of congenital abnormaltities meaning heifers will not reach puberty?

A
  • freeemartinism
  • > ovarian aplasia/hypoplasia
  • occours in heigfers co-twinned to bull calf
  • beware single calf where male co-twin has died
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8
Q

Give 6 main causes of “no observed oestrus”

A
  1. congential abnormalities
  2. true acyclical or anoestrus
  3. overian cysts
  4. persistent CL (usually with pyometra)
  5. limited behaviour signs (sub-oestrus/silent heat)
  6. showing signs but not detected
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9
Q

How may freemartinism be Dx?

A
  • test tube or thermometer case test - insert into vagina to get length of tract (full or vestigial?)
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10
Q

What may casue true anoestrus or acyclicity?

A
  • high milk yield
  • inadequate feeding especially energy
  • poor BCS
  • stress (lamenss etc.)
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11
Q

What will be found on PE of a true anoestrus cow?

A
  • normal involuted tract, ovaries small, smooth and flat
  • ultrasound shos small follicles only, no CL
  • milk P4 at d10 low (usually 0)
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12
Q

How may poor nutrition affect fertility?

A

Via IGF levels

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13
Q

How may true anoestrus be treated?

A
  • wait until NEB state is rectified - increase energy intake and wait for milk yield to decrease
  • hormones:
    GnRH or analogue
    Progesterone/progestgens
    eCG low dose (750IU)
  • better response to hormones if nutrition improved too
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14
Q

How do CIDRs and PRIDs differ?

A

Prid spiral

CIDR Y shaped

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15
Q

Name the 5 types of fluid filled structure that may be found on the bovine ovary, which are normal/abnormal?

A 
> normal 
- follicles
- vacuolated CL
> abnormal 
- luteinised follicles
- follicular/inactive cysts 
- luteal cysts
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16
Q

How do normal follicles feel and what size should they be throughout the cycle?

A
  • transient, dynamic, soft, fluctuant structure
  • max 1.5 - 2cm diameter during/after oestrus
  • <1.5cm rest of cycle
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17
Q

How can vacuolated CLs be distinguished?

A
  • same size as non-vacuolated CLS
  • wiith ovulation point?
  • ID with US
  • vacuole disappears during pregnancy
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18
Q

How can luteinised follicles be distinguished? What are they?

A
  • < 2.5cm diameter
  • no sign of ovulation
  • larger cavity than vacuolated CL
  • formed from leuteinisation of anovulatory follicle
  • usually single
  • occour early post-partum
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19
Q

What are follicular and inactive cysts?

A
  • soft, thin walled (2.5cm diameter
  • single or multiple
  • one or both ovaries
  • formed from anovulatory mature follicles
  • low P4
  • cows are anoestrus
  • nymphomania
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20
Q

What are luteal cysts?

A

Thick walled >3mm fluid filled structure >2.5cm diameter

  • usually single, formed from anovulatory mature follicle
  • HIGH P4
  • cows are anoestrus
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21
Q

What are vacuolated CLs also known as?

A
  • cystic CLs

- this implies pathological which they are not

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22
Q

Define what an ovarian cyst is generally

A

Fluid filled structure on surface of ovary
> 2.5cm diameter (ie. > mature follicle size)
Persisting for longer than 10d
Resulting in suboptimal repro performance
- formed when granulosa cell layer degenerates -> cessation of normal cycling activity and either acylicity or nymphomaniacal

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23
Q

What are the 3 types of cysts?

A 
> follicular
- thin walled
- oestradiol secreting 
- acyclcity or  nymphomaniacal
> luteal 
- thick walled
- progesterone secreting 
- anoestrus due to neg feedback on pituitary 
> inactive
- thin walled
- functionally undiffernetiated and inactive
- usually seen with acyclicity 
- COD
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24
Q

Which cows are cysts often seen in?

A

High yielders

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25
Q

What should cysts not be confused with?

A

vacuolated CLs

26
Q

How many follicular waves may a single cow have during a single cycle?

A

2-4

27
Q

Why do cysts occour?

A
  • LH surge absent or attenuated

this is normal 3-4weeks post-parturition but should then return to normal

28
Q

Why does the LH surge fail to occour?

A

> normal response post-calving
- progressive restoration of the ability of the hypothalamus to respond to oestradiol
- due to lack of sensitivity or hypothalamic LH surge centre to oestradiol or failure of GnRH release
in cystic cows
- v no. LH-Rs on granulosa cells of follicles
- v insulin and IGF1
- NEB-> NEFAs
-> impair follicular cell proliferation and function

29
Q

When do cysts commonly tend to develop? How should these be treated?

A

> immediately post-partum
- will regress spontaneously - no Tx needed!
if lasting longer
- do NOT manually rupture
- treat luteal cysts with PGF2a
- treat follicular cysts with GnRH or hCG to cause luteinisationg, followed by PGF2a or PRID/CIDR for 10-12d (will shrink the cysts)

30
Q

What is a persistent CL? Which types of cows is this seen in commonly? What is debated regarding this pathology?

A
  • extended luteal phase
  • esp high genetic merit cows
  • > debated whether this can occour without concurrent uterine infection (may just be non-detection of oestrus)
  • with pyometra, luteolysin production affected
31
Q

What shouldpersistent CL be treated with?

A

PGF2a

32
Q

What is necessary for a cow to express signs of oestrus?

A
  • “friendly environment”
  • NB: first post partum oestrus likely to not have behavioural signs (due to refraction of hypothalamus to respond to oestradiol)
33
Q

How long does oestrus last in high yielding dairy cows? How does this compare to traditional times?

A

15 hours - less than traditional

34
Q

What may influence oestrus and overtness of behavioural signs?

A

Breeds - Holsteins more difficult to detect

35
Q

What are some signs of oestrus in the cow?

A
  • restlessness, searching for other cows in oestrus, grouping of sexually active cows
  • v eating
  • bellowing if separated
  • clear vulval mucus discharge
  • head moutning
  • standing to be mounted
36
Q

How often should cows be observed for oestrus?

A
  • 20-30mins TID
  • especially 9-10 pm when cows are indisturbed
  • use detection aids or synchronise oestrus with fixed time AI
37
Q

Give egs of oestrus detection aids

A
  • Kamar/Beacon/Estrotect heat moutn detectors
  • pedometers
  • CCTV
  • changes in vaginal impedence
  • milk P4 assays
38
Q

How has oestrus detection been made more objective?

A

Van Eedenburgs scoring system for oestrus detection assigns marks to each sign of oestrus

39
Q

What are alternative approaches to detecting oestrus?

A
  • run bull with the herd (no AI)
  • fixed time AI after oestrus synch with P4/PGF2a
  • more complex ovsynch regimes
40
Q

How is the cycle manipulated to implement fixed time AI?

A 
> 2 injections PGF2a 11d apart 
- single AI 72-84hrs later
- double AI at 72 and 90/96hrs
> PRID/CIDR 7-9d with PGF2a injected 24hrs before removal 
- single AI 56hrs 
- double AI at 48 and 72hrs
41
Q

Outline the ovsynch protocol with GnRH

A
  • d0: GnRH to accelerate follicular development and synchronise new wave emergence
  • d7: PGF (luteolysis)
  • d9: GnRH to cause ovulation
  • d10: AI
42
Q

What is a modified version of ovsynch?

A

Double ovsynch

  • multiple GnRH injections
  • GnRH1, PGF1, GnRH2, GnRH3, PGF2, GnRH4, AI!!!
43
Q

For what reasons may a cow not calve after service/AI?

A
  • 10-15% oocytes not fertilised
  • 15-20% embreyos die 42d (abortion, mummification, maceration)
    > normal cow, this is ok sporadically and will always happen tosome degree
  • persistence is a problem
44
Q

What os regular return to oestrus?

A

Interval between service and return to oestrus 18-24d

early embryo death or fertilisation failure

45
Q

What is irregular return to oestrus?

A

Returns >24d (late embryonic/early foetal death)

or <18d (incorrect identification of oestrus and mistimed AI)

46
Q

Give egs. of reasons for fertilisation failure (other than poor bull/semen)

A
  • anovulation/delayed
  • incorrect AI timing inc serving too early post-partum
  • hormonal deficiency/imbalance
  • structural defects of tubular geneital tract (hydrosalpinx, adhesions)
  • infection (endometritis)
  • nutritional deficiency and imbalance
  • stress
47
Q

How do cattle differ in timing of ovulation cf. other domestic spp?

A

All other spp. ovulate during behavioural oestrus

- cattle 12 hours later

48
Q

Causes of early and late embryonic death

A
  • luteal deficiency/hormone imbalance
  • uterine infection with specific embreyopathic microorganisms
  • infection with opportunist pathogens and endometriits
  • nutritional imbalance
  • genetic factos
  • stress eg. heat
49
Q

How can luteal deficiency and hormonal imbalance be Dx and tx?

A

Dx - difficult to Dx (endocrine levels transient)
Tx - P4 supplementation after insemination (some success)
- hCG 4-9d post AI casues accessory CL formation
- Tx as for endometritis if discharge indicates any sort of opportunistic pathogen infection

50
Q

Egs. specific embryopathic microbes

A
  • campylobacter foetus
  • tritrichomonas foetus
  • mycoplasma, ureaplasma, acholplasma
  • BVDV
  • IBR
  • Blue tongue
  • chlamydophila psittaci
51
Q

What defines a repeat breeder?

A
  • comes back into season >3 times (normal or extended)
52
Q

What is the empirical Tx for a repeat breeder?

A
  • change sire - different breed?
  • good fertiltiy bull
  • inseminate 2x 24hr intervals
  • hCG (==LH) or GnRH at time of first AI
  • GnRH analogue (eg. Buserelin) 11-12d post AI
  • PRID/CIDR 11-12d
53
Q

What is the different between metritis and endometirits? What would be seen on smear with either?

A
  • endometritis = inner lining
  • metirits = full thickness
  • > neutrophils
54
Q

Predisposing factors for endometritis?

A
  • long/short gestation
  • retained foetal membranes
  • parity
  • milk yield
  • dystocia and trauma
  • hygeine
  • season of year
  • intercurrent disease
  • nutrition
  • early/delayed return to oestrus
55
Q

How is endometritis Dx?

A

> vaginal examination
- character, volume and smell of discharge
scoring for severity
bacteriology v difficult

56
Q

Common causes of endometritis?

A
  • trueperella pyogenes
  • prevotella spp
  • E. COli
  • fusobacterium necrorum
  • fusobacterium nucleatum
57
Q

Txof endometritis? What does this depend on?

A
  • CL present: PGF
  • No CL: metricure (IU cephalosporine)
  • chronic lesions may consider povidine iodine
58
Q

How is abortion and stillbirth defined?

A

271d = stillborn

59
Q

Non-infectious causes of abortion/stillbirth?

A
  • chromosomal/genetic abnormalities
  • endocrine imblaance
  • toxic
  • heat stress
  • misuse of therapeutic substances (corticosteroids and PGs)
  • dystocia
60
Q

Commonest infectious causes of bovine fetopathy?

A
  • Neospora
  • Bacillus lichenformis
  • Trueperella pyogenes
  • Salmonella dublin
  • Smallenburg
61
Q

In which spp is specific dx of causal agent most common?

A

Sheep (can send whole lamb wheras cow only send organs)

62
Q

Give 12 infectious causes of abortion and the stage of pregnancy at which the cow will abort. Which are venereal? (Mark *)

A
  1. Fungi (aspergillus, absida, mortiella spp mucoralis group) 4mo -> term
    * 2. IBR-IPV virus 4-7mo
    * 3. Tritrichomonas foetus 5mo
    * 4. Campylobacter fetus (venerealis) 5-7mo
  2. Leptospira spp 6-9mo
  3. Listeria monocytogenes 6-9mo
  4. Brucella Abortus 6-9mo
  5. Salmonella spp ~7mo, variable
  6. Trueperella (arcanobacter) pyogenes sporadic, variable time
  7. Bacillus licheniformis: sporadic late term
  8. Mycobacterium TB any stage
    * 12. BVDV any stage

Reproduction (30 decks)

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