Fertility, sub-fertility + infertility in the cow Flashcards
changes in cow fertility
increased milk yields have decreased fertility
calving rates are also decreasing with time
sub-fertility - causes
structural, functional, management causes
infectious agents
sub-fertility - signs
no observed oestrus
regular or irregular returns to oestrus after natural service or AI
presence of abnormal vulval discharge
abortion + stillbirth
no observed oestrus
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
no observed oestrus in heifers
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)
no observed oestrus in cow
anoestrus or true acyclicity cystic ovarian disease persistent CL? pyometra with a persistent CL sub-oestrus failure to detect oestrus
anoestrus or true acyclicity - causes
high milk yields
inadequate feeding especially energy
poor body condition
stress - lameness, intercurrent disease
anoestrus or true acyclicity - clinical exam
rectal palpation shows involuted tract, ovaries feel small, smooth, flat
ultrasound shows follicles <1.5cm, no CL
milk progesterone at 10 day intervals low
low IGF-1 levels due to poor nutrition - affects
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
anoestrus or true acyclicity - treatment
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
follicular + inactive cysts
abnormal soft, thin walled, fluid filled single or multiple, one or both ovaries from anovulatory mature follicle low P4, same as acyclic cow persistent
luteal cysts
abnormal thick-walled, fluid filled usually single from anovulatory mature follicle high P4, cows are anoestrus persistent
what are ovarian cysts?
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
3 types of cysts
thin walled, oestradiol secreting follicular cyst - true follicular cyst
thick walled, progesterone secreting luteal cyst - luteal cyst
thin walled, inactive cyst - inactive cyst
classification of ovarian cysts
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
why do cysts occur - hypothalamic/pituitary causes
normally LH surge absent or attenuated after calving
cysts occur because of failure of pre-ovulatory LH surge after end of recovery period
failure of LH surge
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
why do cysts occur - ovarian causes
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
ovarian cysts - treatment
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
persistent CL
occurence associated with pyometra where pathological changes to uterus interferes with luteolysin production + CL persists which self perpetuates the disease
persistent CL - treatment
PGF2a
sub-oestrus + failure to detect oestrus
reduced oestrus expression
good environment needed for cows to express oestrus
in high yield cows duration of oestrus is less than traditional 15h
signs of oestrus in cow
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
why is oestrus not detected
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
oestrus detection aids
heat mount detectors/tail paint
pedometers
changes in vaginal impedence
sequential milk progesterone assays
reasons for cow not calving after service
10-15% oocytes not fertilised
15-20% embryos die <13 days
10% embryos die 13-42 days
5% foetal death after 42 days
regular return to oestrus
where interval between service + return to oestrus is 18-24 days due to fertilisation or early embryonic death
irregular returns
intervals either >24 days where cause is late embryonic or early foetal death
mistimed AI due to incorrect identification of oestrus
causes of fertilisation failure - non bull related
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
early + late embryonic death - causes
luteal deficiency + hormone imbalance
uterine infection with specific embryopathic microrganisms
infection with opportunist pathogens + endometritis
nutritional deficiencies + excesses
heat + other stressors
early + late embryonic death - diagnosis
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?
specific embryopathic micro-organisms
campylobacter fetus tritrichomonas fetus mycoplasma, ureaplasma + acholeplasa bovine viral diarrhoea virus (BVDV) infectious bovine rhinotracheitis (IBR) blue tongue virus chlamydophilia psittaci
treating repeat breeder cow
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
effects of infectious agents on fertility of heifers + cows
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
endometritis - predisposing factors
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
endometritis - diagnosis
vaginal exam essential - character, volume, smell
scoring for severity
bacteriology v.difficult
endometritis - common bacterial agents
trueperella (arcanobacterium) pyogenes prevotella species escherichia coli fusobacterium necrophorum fusobacterium nucleatum
endometritis - treatment
CL present - PGF
no CL - metricure, intrauterine cephalosporin
chronic lesions, fail to respond to treatment
abortion - define
expulsion of one or more calves 271 days after service either dead or alive for <24h
stillbirth - death
birth of dead calf at full term
non-infectious causes of abortion/stillbirth
genetic factors - chromosomal/developmental abnormalities
endocrine deficiencies + excesses
toxic substances
heat stress
misuse of therapeutic substances such as corticosteriods and PGs
dystocia (stillbirth)
specific, non-venereal infectious causes of abortion
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
specific, venereal infectious causes of abortion
campylobacter fetus - 5-7 months
tritrichomonas fetus - 5 months
IBR-IPV virus - 4-7 months
BVDV - any stage
luteinised follicles
abnormal
<2,5cm, no sign of ovulation, larger cavity than vacuolated CL
usually single from anovulatory mature follicle
occur early postpartum
