Flashcards in Cattle Infertility 1 + 2 Deck (62):
Define infertile, subfertile and fertile cows.
- 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
Is the fertility of cows changing?
- ^ milk yield correlates with v fertility
What are the 4 traditional cuases of sub-fertility in caltle?
What are the usual presenting 4 clinical signs of sub-fertility?
- no observed oestrus
- regular/irregular returns to oestrus after natural service/AI
- Presence of abnormal vulval discharge
- abortion and stillbirth
Why may some heifers never reach puberty?
- congential abnormaltities
Once puberty has been reached, how frequently will she come into oestrus? What are the exceptions to this?
- unless pregnant or 4-6 weeks post partum
What is the most common cause of congenital abnormaltities meaning heifers will not reach puberty?
-> ovarian aplasia/hypoplasia
- occours in heigfers co-twinned to bull calf
- beware single calf where male co-twin has died
Give 6 main causes of "no observed oestrus"
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
How may freemartinism be Dx?
- test tube or thermometer case test - insert into vagina to get length of tract (full or vestigial?)
What may casue true anoestrus or acyclicity?
- high milk yield
- inadequate feeding especially energy
- poor BCS
- stress (lamenss etc.)
What will be found on PE of a true anoestrus cow?
- normal involuted tract, ovaries small, smooth and flat
- ultrasound shos small follicles only, no CL
- milk P4 at d10 low (usually 0)
How may poor nutrition affect fertility?
Via IGF levels
How may true anoestrus be treated?
- wait until NEB state is rectified - increase energy intake and wait for milk yield to decrease
GnRH or analogue
eCG low dose (750IU)
- better response to hormones if nutrition improved too
How do CIDRs and PRIDs differ?
CIDR Y shaped
Name the 5 types of fluid filled structure that may be found on the bovine ovary, which are normal/abnormal?
- vacuolated CL
- luteinised follicles
- follicular/inactive cysts
- luteal cysts
How do normal follicles feel and what size should they be throughout the cycle?
- transient, dynamic, soft, fluctuant structure
- max 1.5 - 2cm diameter during/after oestrus
- <1.5cm rest of cycle
How can vacuolated CLs be distinguished?
- same size as non-vacuolated CLS
- wiith ovulation point?
- ID with US
- vacuole disappears during pregnancy
How can luteinised follicles be distinguished? What are they?
- < 2.5cm diameter
- no sign of ovulation
- larger cavity than vacuolated CL
- formed from leuteinisation of anovulatory follicle
- usually single
- occour early post-partum
What are follicular and inactive cysts?
- soft, thin walled (2.5cm diameter
- single or multiple
- one or both ovaries
- formed from anovulatory mature follicles
- low P4
- cows are anoestrus
What are luteal cysts?
Thick walled >3mm fluid filled structure >2.5cm diameter
- usually single, formed from anovulatory mature follicle
- HIGH P4
- cows are anoestrus
What are vacuolated CLs also known as?
- cystic CLs
- this implies pathological which they are not
Define what an ovarian cyst is generally
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
What are the 3 types of cysts?
- thin walled
- oestradiol secreting
- acyclcity or nymphomaniacal
- thick walled
- progesterone secreting
- anoestrus due to neg feedback on pituitary
- thin walled
- functionally undiffernetiated and inactive
- usually seen with acyclicity
Which cows are cysts often seen in?
What should cysts not be confused with?
How many follicular waves may a single cow have during a single cycle?
Why do cysts occour?
- LH surge absent or attenuated
(this is normal 3-4weeks post-parturition but should then return to normal)
Why does the LH surge fail to occour?
> 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
When do cysts commonly tend to develop? How should these be treated?
> 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)
What is a persistent CL? Which types of cows is this seen in commonly? What is debated regarding this pathology?
- 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
What shouldpersistent CL be treated with?
What is necessary for a cow to express signs of oestrus?
- "friendly environment"
- NB: first post partum oestrus likely to not have behavioural signs (due to refraction of hypothalamus to respond to oestradiol)
How long does oestrus last in high yielding dairy cows? How does this compare to traditional times?
15 hours - less than traditional
What may influence oestrus and overtness of behavioural signs?
Breeds - Holsteins more difficult to detect
What are some signs of oestrus in the cow?
- 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
How often should cows be observed for oestrus?
- 20-30mins TID
- especially 9-10 pm when cows are indisturbed
- use detection aids or synchronise oestrus with fixed time AI
Give egs of oestrus detection aids
- Kamar/Beacon/Estrotect heat moutn detectors
- changes in vaginal impedence
- milk P4 assays
How has oestrus detection been made more objective?
Van Eedenburgs scoring system for oestrus detection assigns marks to each sign of oestrus
What are alternative approaches to detecting oestrus?
- run bull with the herd (no AI)
- fixed time AI after oestrus synch with P4/PGF2a
- more complex ovsynch regimes
How is the cycle manipulated to implement fixed time AI?
> 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
Outline the ovsynch protocol with GnRH
- d0: GnRH to accelerate follicular development and synchronise new wave emergence
- d7: PGF (luteolysis)
- d9: GnRH to cause ovulation
- d10: AI
What is a modified version of ovsynch?
- multiple GnRH injections
- GnRH1, PGF1, GnRH2, GnRH3, PGF2, GnRH4, AI!!!
For what reasons may a cow not calve after service/AI?
- 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
What os regular return to oestrus?
Interval between service and return to oestrus 18-24d
(early embryo death or fertilisation failure)
What is irregular return to oestrus?
Returns >24d (late embryonic/early foetal death)
or <18d (incorrect identification of oestrus and mistimed AI)
Give egs. of reasons for fertilisation failure (other than poor bull/semen)
- 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
How do cattle differ in timing of ovulation cf. other domestic spp?
All other spp. ovulate during behavioural oestrus
- cattle 12 hours later
Causes of early and late embryonic death
- luteal deficiency/hormone imbalance
- uterine infection with specific embreyopathic microorganisms
- infection with opportunist pathogens and endometriits
- nutritional imbalance
- genetic factos
- stress eg. heat
How can luteal deficiency and hormonal imbalance be Dx and tx?
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
Egs. specific embryopathic microbes
- campylobacter foetus
- tritrichomonas foetus
- mycoplasma, ureaplasma, acholplasma
- Blue tongue
- chlamydophila psittaci
What defines a repeat breeder?
- comes back into season >3 times (normal or extended)
What is the empirical Tx for a repeat breeder?
- 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
What is the different between metritis and endometirits? What would be seen on smear with either?
- endometritis = inner lining
- metirits = full thickness
Predisposing factors for endometritis?
- retained foetal membranes
- milk yield
- dystocia and trauma
- season of year
- intercurrent disease
- early/delayed return to oestrus
How is endometritis Dx?
> vaginal examination
- character, volume and smell of discharge
> scoring for severity
> bacteriology v difficult
Common causes of endometritis?
- trueperella pyogenes
- prevotella spp
- E. COli
- fusobacterium necrorum
- fusobacterium nucleatum
Txof endometritis? What does this depend on?
- CL present: PGF
- No CL: metricure (IU cephalosporine)
- chronic lesions may consider povidine iodine
How is abortion and stillbirth defined?
271d = stillborn
Non-infectious causes of abortion/stillbirth?
- chromosomal/genetic abnormalities
- endocrine imblaance
- heat stress
- misuse of therapeutic substances (corticosteroids and PGs)
Commonest infectious causes of bovine fetopathy?
- Bacillus lichenformis
- Trueperella pyogenes
- Salmonella dublin
In which spp is specific dx of causal agent most common?
Sheep (can send whole lamb wheras cow only send organs)