Reproduction Flashcards
where is the main control point for the reproductive endocrinology?
hypothalamus
what hormone is released from the hypothalamus that controls reproduction?
GnRH
what does GnRH work on in the endocrine reproductive pathway?
pituitary gland
what does GnRH trigger to be released from the pituitary gland?
FSH and LH
what is GnRH?
gonadotrophin releasing hormone
what does FSH do?
stimulate development of follicles in the ovary (follicle stimulating hormone)
what does LH do?
causes the dominant follicle to ovulate and triggers it to lutenise to become a corpus luteum
what does the follicle produce as its developing?
oestrogen
what are the effects of oestrogen on the reproductive endocrinology?
negative feedback on FSH (stop other follicular development)
gives signs of heat
what does the follicle develop into after ovulation?
corpus luteum
what hormone is produced by the corpus luteum?
progesterone
what is the function of progesterone?
prepare the uterus for pregnancy (if CL isn’t lysed)
what is the first stage of the follicle developing into a CL?
corpus haemorrhagicum
what does oestrogen have negative feedback on?
brain (neurotransmitters)
hypothalamus (GnRH)
anterior pituitary (LH/FSH)
what happens to the first follicle after calving?
not exposed to progesterone so is smaller and produces less oestridioll
why is the first cycle after calving often silent?
no progesterone so the follicle is smaller and produces less oestradiol so no/less signs of heat are seen
what does progesterone have a negative feedback on?
LH (no ovulation can occur shortly after another)
how is metoestrus usually detectable?
small amount of blood on vaginal exam
small ovaries on rectal
how do pulses of LH change as ovulation gets nearer?
the pulses increase in frequency (causing increase in blood levels)
how long does it take dairy and beef cows to return to cycling?
dairy cows usually within a few weeks
beef cows can take a few months
what is the best sign of oestrus?
cow stands to be mounted
what are the signs of oestrus?
vulva swelling and mucus discharge
holding milk
restless
mounts other cows
chin resting
standing to be mounted
which cow is in heat if one is sniffing another vulva?
the cow doing the sniffing is in oestrus
if a cow is chin resting on another which is in oestrus?
both of them
if cows are bunting each other, which one is in oestrus?
both of them
if a cow mounts another head to head, which is in oestrus?
the one doing the mounting
if a cow mounts another, which is in heat?
the one standing to be mounted
when should a cow seen standing to be mounted be served?
AM PM rule (if seen in morning serve in evening)
what is the best time to inspect cows for heat detection?
when they are resting and the barn is quiet - not about to be milked or moved around
what are some heat detection aids?
paint/chalk or kamars
record keeping (21 day cycle)
teaser animals
milk progesterone (decreases detected)
activity monitors
what are the limitations for mount detectors?
not all cows show standing heat, can be hit/rubbed by brushes
how do activity monitors detect heat?
monitor ever few hours to get a basal activity level, then creates a mean
if there is movement more than 5 standard deviations away from the mean it is marked as in oestrus
how does rumen activity change in oestrus?
decreases
how many sperm are in an AI straw on conventional semen?
20 million
how many sperm are in an AI straw of sexed semen?
1 million
how are AI straws thawed?
in a water bath at 37 degrees for 40 seconds
what is the role of KPIs?
demonstrate efficiency of herd
show good animal health/welfare
provides a benchmark to aim for
what are the requirements of a good KPI?
measurable
convenient
low cost
where could data be available for analysis of a herd?
legal farm records (medicine, movements…)
product purchaser (deadweight, milk sales…)
from supplies (feed input, AI straws…)
veterinary computers
farm diary
milk recording (NMR, CIS…)
what are some specific KPIs for monitoring fertility?
submission rate (number of animals severed out of number that are eligible)
first service submission rate (all animals who haven’t been served after the earliest service date)
calving to first service
calving interval
calving to conception interval
in calf rate (by 100 days…)
what is the issue with using calving interval as a KPI?
must have had two calves (doesn’t take into account a large portion of the herd)
what is the issue with using calving to conception interval as a KPI?
will get worse as animals conceive (problem cows will conceive last)
what is the conception rate?
number of pregnancies for those cows who have been served
what is the main advantage/disadvantage of late PDing?
advantage - more predictable of those who will hold the calf
disadvantage - longer before you can do something about the negative cows
what is preg rate?
number of pregnant cows over the number of which are eligible to be pregnant (over 3 weeks)
when does the heart begin beating in an embryo?
23 days
when does the maternal recognition of pregnancy occur?
15 days
what is a cu-sum for tracking conception rate?
graph where the line moves up one if the PD positive and down if they PD negative (gives you a conception rate) - can pinpoint times when things went good/bad
what does inter service interval tell you?
how accurate the heat detection is (should be 3 weeks)
where does fertilisation occur?
oviduct
what hormone is crucial for embryo growth?
progesterone
how does maternal recognition of pregnancy occur in cows?
size of embryo determines this, as it produces interferon (bigger the embryo the more interferon and more successful the MRP will be)
what happens if there is no implantation of an embryo in cattle?
oxytocin is able to bind to its receptors which triggers prostaglandin F2alpha and lysis of the CL occurs
what is the interferon for maternal recognition of pregnancy?
interferon tau
what day does the embryo become visible to scanning?
27/28
what hormone maintains pregnancy?
progesterone
what is the hormonal triggers of parturition?
calf stress produces cortisol which triggers prostaglandin release and reduced progesterone
what organs does cortisol from the calf at parturition aid the development of?
lungs
what has to happen after calving for the successful establishment of the next pregnancy?
involution of uterus
restoration of endometrium
resumption of ovarian cycling
insemination/fertilisation
what are the levels of hormones after calving?
oestrogen and progesterone are low
FSH surges increase after a few days
what are some reasons for early embryonic loss?
(fertilisation failure)
uterine environment
infectious agents (BVD, lepto…)
metabolic status of dam
genetic abnormality
what are some issues seen post calving by a vet/farmer?
retained foetal membranes
metritis/endometritis
cystic ovarian disease
failure to resume cycling
what is a possible cause for irregularly cycling of served cows?
insufficient interferon tau being produced causing early embryonic death as it can’t implant
how long does a placenta have to stay in the cow to be classed as a retained foetal membrane?
24 hours
what are the consequences of retained foetal membranes?
low milk yield
longer time to involute (longer to resume oestrus cycling)
metritis, endometritis, pyometra
what is metritis?
infection of the uterus up to 21 days post calving
what are the consequences of uterine infections?
damage to uterus
suppress hypothalamic GnRH secretion
localised effect on ovarian function
what are the main pathogens for uterine infection?
E. coli
Truperella pyogenes
Dichelobacter nodosus
(bovine herpes virus 4)
what are some possible risk factors for retained foetal membranes?
reduced dry matter intake in dry period
negative energy balance after calving
vitamin A/D/E deficiency
iodine deficiency
what are is grade 1 metritis?
enlarged uterus and purulent uterine discharge but no pyrexia/illness
what is grade 2 metritis?
overt systemic illness (pyrexia, milk drop…)
what is grade 3 metritis?
toxaemic metritis
what is pyometra?
accumulation of purulent material within the uterine lumen in the presence of a CL and closed cervix
what is done to treat a pyometra?
prostaglandin (lyse CL)
what is clinical endometritis?
presence of purulent uterine discharge detectable in the vagina over 21 days post calving
what is a grade 1 uterine discharge score?
flecks of off white pus
what is grade 2 uterine discharge score?
<50% off white material
what is grade 3 uterine discharge score?
> 50% off white material and possibly blood stained
what grade endometritis is treated?
grade 2 and 3
what grade endometritis is treated?
grade 2 and 3
what is sub-clinical endometritis?
high neutrophil count in the uterus (no discharge or bacteria)
what are the risk factors for sub-clinical endometritis?
negative energy balance
metritis
how is sub-clinical endometritis diagnosed?
can only be done by flushing uterus with saline or a cytobrush
what is a follicular cyst?
a follicle that hasn’t ovulated and has kept growing
what is a luteal cyst?
a follicular cyst that has lutenised
what are some risk factors associated with cystic ovarian disease?
high milk production
negative energy balance
ketosis
higher parity
twinning and peri-parturient problems
excess BCS
genetics
if there is a CL (>2cm) present on one ovary and a follicular cyst on the other, what should be treated?
CL (follicular cyst will be hormonally inactive)
what are the features of a follicular cyst?
thin wall
fluid filled
been there more than 10 days
>25mm
how active is a follicular cyst if there are other follicles present on the ovary?
cyst inactive (not secreting estradiol)
what are the features of a luteal cyst?
> 25mm
thick wall
fluid filled lacuna
been there more than 10 days
what are the treatment options for follicular cysts?
burst
GnRH
progesterone (PRID/CIDR)
aspirate
what is done to treat a luteal cyst?
prostaglandin
what is abortion defined as?
calving that occurs <270 days of gestation
what disease is the reason abortions need to be reported?
brucellosis
what is the statutory testing for brucellosis?
blood, vaginal swab and milk (if possible)
what are infectious primary abortion agents?
pathogens that cross the feto-maternal barrier
what are some possible non-infectious causes of abortion?
nutrition - iodine, selenium, energy balance
developmental - hormones, congenital abnormalities
toxins - aflatoxins, nitrate
trauma, hyperthermia, twinning
what are some possible target tissue of abortion agents?
chorio-allantois
amnion
bone
soft tissue
endocrine glands
immune cells of foetus
what is the definition of a primary abortive agent?
agent that destroys the integrity of the fete-maternal unit allowing opportunistic pathogens to invade the placenta/fetus
what are some primary infectious abortion agents?
brucella abortus
BVD
leptospirosis
neospora
BHV-1
parainfluenza 3
bacillus licheniformis
fungi
what are the main opportunistic pathogens causing abortion?
Listeria monocytogenes
Leptospira borgpetersenii
Salmonella dublin
what are the three routes of infection for abortion pathogens?
resident flora of reproductive tract during pregnancy
transplacental
haematogenous
when in gestation does the foetus become able to differentiate between antigen and self?
90-120 days
what in the pathogen for IBR?
bovine herpesvirus 1
where is BHV-1 found during latent infection?
trigeminal ganglion
how can a vaccine be used for IBR?
protection in the face of an outbreak
what is the most commonly diagnosed cause of abortion in cattle?
neospora
when does neospora usually cause abortion?
mid gestation
how many abortions does neospora cause per cow?
only one (usually)
what are the possible outcomes of a cow with neospora? (in terms of pregnancy)
10% abortions
80% persistant infection
10% normal/weak
why is neospora difficult to diagnose in cattle?
maternal antibodies fluctuate throughout reproductive cycle
when is the best time to test for neospora antibodies in dams?
just after dry off
what is the best way to diagnose neospora?
test calf before its had colostrum
how can neospora be controlled?
keep dogs away from feed and placentas
culling seropositive animals/offspring
breed to beef
sexed semen in unaffected heifers
what are the possible outcomes of BVD if infected during pregnancy?
early - resorption/abortion
90-120 days - immunotoleranc (PI animal)
late - sero-positive and congenital abnormalities
what biotype of BVD causes issues in pregnant cattle?
non-cytopathic
what are the classic congenital abnormalities of BVD?
cataracts
cerebellar hypoplasia
what is the antibody and antigen status of PI BVD calves?
antibody negative
antigen positive
what causes mucosal disease?
PI BVD animals that become infected with the cytopathic biotype
what are the possible ways to diagnose BVD?
bulk milk antibody
PI in blood from 1 months of age
ear notch test
antibody using bloods
how is BVD controlled?
test bought in cattle
good biosecurity
test and cull
vaccine (just protects first pregnancy)
why is leptospirosis a concern in the parlour?
excreted in urine and is zoonotic
what are to clinical signs of leptospirosis?
abortions, stillbirths, weak calves, retained foetal membranes, infertility
how can clinical leptospirosis be treated?
antibiotics - oxytetracycline or dihydrosteptomycin
