Fertility, sub-fertility + infertility in the cow Flashcards

1
Q

changes in cow fertility

A

increased milk yields have decreased fertility

calving rates are also decreasing with time

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2
Q

sub-fertility - causes

A

structural, functional, management causes

infectious agents

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3
Q

sub-fertility - signs

A

no observed oestrus
regular or irregular returns to oestrus after natural service or AI
presence of abnormal vulval discharge
abortion + stillbirth

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4
Q

no observed oestrus

A

some heifers don’t reach puberty - congenital abnormalities eg. ovarian aplasia + hypoplasia ( freemartinism is most common cause)
acyclical or anoestrus (not enough energy)
ovarian cysts
showing signs but not detected
cycling but no visible signs

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5
Q

no observed oestrus in heifers

A

ovarian aplasia + hypoplasia are v.rare
92% of heifers that are co-twins to bull calves are freemartins (beware single born freemartins)
never cycle, small vestigial tract with no ovaries (freemartin)

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6
Q

no observed oestrus in cow

A
anoestrus or true acyclicity
cystic ovarian disease
persistent CL?
pyometra with a persistent CL
sub-oestrus
failure to detect oestrus
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7
Q

anoestrus or true acyclicity - causes

A

high milk yields
inadequate feeding especially energy
poor body condition
stress - lameness, intercurrent disease

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8
Q

anoestrus or true acyclicity - clinical exam

A

rectal palpation shows involuted tract, ovaries feel small, smooth, flat
ultrasound shows follicles <1.5cm, no CL
milk progesterone at 10 day intervals low

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9
Q

low IGF-1 levels due to poor nutrition - affects

A

hypothalamus - decr GnRH secretion
pituitary - decr LH + FSH secretion, response to GnRH
ovary - decr granulosa proliferation + differentiation, LH/FSH supported steriodogenesis, aromatase activity, luteal activity + steriodogenesis
embryo - decr growth, IFN tau production

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10
Q

anoestrus or true acyclicity - treatment

A

wait until milk yields fall, or cow returns to +ve energy balance, incr energy intake if possible
hormones - GnRH or analogue, PRID, CIDR either alone or with GnRH or eCG (equine chorionic gonadotrophin)
better response to hormones with concurrent nutrition improvement

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11
Q

follicular + inactive cysts

A
abnormal
soft, thin walled, fluid filled
single or multiple, one or both ovaries from  anovulatory mature follicle
low P4, same as acyclic cow
persistent
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12
Q

luteal cysts

A
abnormal
thick-walled, fluid filled
usually single from anovulatory mature follicle
high P4, cows are anoestrus
persistent
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13
Q

what are ovarian cysts?

A

fluid filled structures on the ovaries
larger than mature follicle
persist for longer than 10 days
results in aberrant reproductive function
develop from anovulatory graafian follicles in which the granulosa cell layer degenerates with cessation of normal cyclical activity - cow becomes acyclical or nymphomaniacal

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14
Q

3 types of cysts

A

thin walled, oestradiol secreting follicular cyst - true follicular cyst
thick walled, progesterone secreting luteal cyst - luteal cyst
thin walled, inactive cyst - inactive cyst

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15
Q

classification of ovarian cysts

A

thin walled follicular cysts result in acyclicity or nymphomania
lutal cysts result in acyclicity due to -ve feedback of P4 on anterior pituitary
cystic ovarian disease common with up to 20% cows affected in some herds
not to be confused with vaculolated CL

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16
Q

why do cysts occur - hypothalamic/pituitary causes

A

normally LH surge absent or attenuated after calving

cysts occur because of failure of pre-ovulatory LH surge after end of recovery period

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17
Q

failure of LH surge

A

post calving - progressive restoration of ability of hypothalamus to respond to oestradiol to produce LH surge, due to lack of sensitivity of hypothalamic LH surge centre to oestradiol or failure of GnRH release
failure of oestradiol to elicit normal +ve feedback stimulation of LH surge

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18
Q

why do cysts occur - ovarian causes

A

reduced numbers of LH receptors in granulosa cell of cysts vs normal follicles
low insulin + IGF-1 + -ve energy balance causes > NEFAs impair follicular cell proliferation + function

19
Q

ovarian cysts - treatment

A

cows often develop cysts in post partum that regress on their own
don’t rupture by squeezing rectally
luteal cysts - PGF2a
follicular cyst - GnRH or hCG to cause luteinisation followed by PGF2a, or intra-vaginal CIDR or PRID for 10-12 days
good recovery rates

20
Q

persistent CL

A

occurence associated with pyometra where pathological changes to uterus interferes with luteolysin production + CL persists which self perpetuates the disease

21
Q

persistent CL - treatment

A

PGF2a

22
Q

sub-oestrus + failure to detect oestrus

A

reduced oestrus expression
good environment needed for cows to express oestrus
in high yield cows duration of oestrus is less than traditional 15h

23
Q

signs of oestrus in cow

A
restless, not eating + decr milk yield
search for other cows in oestrus for mounting
grouping of sexually active cows
bellowing if seperated
clear vulval elastic mucus discharge
stand to be mounted
24
Q

why is oestrus not detected

A

short oestrus + signs covert
usually poor facilities + observational regimen
cows should be checked 20-30mins 3x a day
use detection aids or synch oestrus with fixed-time AI

25
Q

oestrus detection aids

A

heat mount detectors/tail paint
pedometers
changes in vaginal impedence
sequential milk progesterone assays

26
Q

reasons for cow not calving after service

A

10-15% oocytes not fertilised
15-20% embryos die <13 days
10% embryos die 13-42 days
5% foetal death after 42 days

27
Q

regular return to oestrus

A

where interval between service + return to oestrus is 18-24 days due to fertilisation or early embryonic death

28
Q

irregular returns

A

intervals either >24 days where cause is late embryonic or early foetal death
mistimed AI due to incorrect identification of oestrus

29
Q

causes of fertilisation failure - non bull related

A
anovulation
delayed ovulation
incorrect timing of AI
serving too early postpartum
hormonal deficiences + imbalance
structural defects of tubular genital tract preventing sperm + oocyte meeting
infection of genital tract + endometritis
nutritional deficiencies + imbalances
stress
30
Q

early + late embryonic death - causes

A

luteal deficiency + hormone imbalance
uterine infection with specific embryopathic microrganisms
infection with opportunist pathogens + endometritis
nutritional deficiencies + excesses
heat + other stressors

31
Q

early + late embryonic death - diagnosis

A

luteal deficiency + hormone imbalance - difficult to diagnose, some success with P4 supplementation using PRID or CIDRs
opportunist pathogens + endometritis - unlikely in abscence of clinical signs, treat as for endometritis, cost effective?

32
Q

specific embryopathic micro-organisms

A
campylobacter fetus
tritrichomonas fetus
mycoplasma, ureaplasma + acholeplasa
bovine viral diarrhoea virus (BVDV)
infectious bovine rhinotracheitis (IBR)
blue tongue virus
chlamydophilia psittaci
33
Q

treating repeat breeder cow

A
change sire if used repeatedly, natural service if possible
use semen from bull with good fertility
inseminate at normal time + 24h after
hCG or GnRH at time of first AI
11-12 days after AI, GnRH analogue
11-12 days consider use of PRID or CIDR
34
Q

effects of infectious agents on fertility of heifers + cows

A

prevent fertilisation - return to oestrus at normal interval
causes early embryonic death - eturn to oestrus at normal interval
causes late embryonic death - eturn to oestrus at extended interval
causes abortion - still birth, weakly calves

35
Q

endometritis - predisposing factors

A
longer/shorter gestation length
retained foetal membranes
parity
milk yield
dystocia + trauma
hygiene
season of year
intercurrent disease
nutrition
early or delayed return to oestrus
36
Q

endometritis - diagnosis

A

vaginal exam essential - character, volume, smell
scoring for severity
bacteriology v.difficult

37
Q

endometritis - common bacterial agents

A
trueperella (arcanobacterium) pyogenes
prevotella species
escherichia coli
fusobacterium necrophorum
fusobacterium nucleatum
38
Q

endometritis - treatment

A

CL present - PGF
no CL - metricure, intrauterine cephalosporin
chronic lesions, fail to respond to treatment

39
Q

abortion - define

A

expulsion of one or more calves 271 days after service either dead or alive for <24h

40
Q

stillbirth - death

A

birth of dead calf at full term

41
Q

non-infectious causes of abortion/stillbirth

A

genetic factors - chromosomal/developmental abnormalities
endocrine deficiencies + excesses
toxic substances
heat stress
misuse of therapeutic substances such as corticosteriods and PGs
dystocia (stillbirth)

42
Q

specific, non-venereal infectious causes of abortion

A
brucella abortus - 6-9 months
leptospira spp - 6-9 months
listeria monocytogenes - 6-9 months
salmonella.spp - variable time
trueperella (arcanobacterium) pyogenes
mycobacterium tuberculosis - any stage
fungi - aspergillus, absidia, mortiella
bacillus licheniformis - late abortions
neospora caninum - late abortions
43
Q

specific, venereal infectious causes of abortion

A

campylobacter fetus - 5-7 months
tritrichomonas fetus - 5 months
IBR-IPV virus - 4-7 months
BVDV - any stage

44
Q

luteinised follicles

A

abnormal
<2,5cm, no sign of ovulation, larger cavity than vacuolated CL
usually single from anovulatory mature follicle
occur early postpartum